@article{zhang_kowalik_mao_damirchi_zhang_bradford_li_duin_zhu_2023, title={Joint Theoretical and Experimental Study of Stress Graphitization in Aligned Carbon Nanotube/Carbon Matrix Composites}, volume={15}, ISSN={["1944-8252"]}, DOI={10.1021/acsami.3c03209}, abstractNote={Stress graphitization is a unique phenomenon at the carbon nanotube (CNT)-matrix interfaces in CNT/carbon matrix (CNT/C) composites. A lack of fundamental atomistic understanding of its evolution mechanisms and a gap between the theoretical and experimental research have hindered the pursuit of utilizing this phenomenon for producing ultrahigh-performance CNT/C composites. Here, we performed reactive molecular dynamics simulations along with an experimental study to explore stress graphitization mechanisms of a CNT/polyacrylonitrile (PAN)-based carbon matrix composite. Different CNT contents in the composite were considered, while the nanotube alignment was controlled in one direction in the simulations. We observe that the system with a higher CNT content exhibits higher localized stress concentration in the periphery of CNTs, causing alignment of the nitrile groups in the PAN matrix along the CNTs, which subsequently results in preferential dehydrogenation and clustering of carbon rings and eventually graphitization of the PAN matrix when carbonized at 1500 K. These simulation results have been validated by experimentally produced CNT/PAN-based carbon matrix composite films, with transmission electron microscopy images showing the formation of additional graphitic layers converted by the PAN matrix around CNTs, where 82 and 144% improvements of the tensile strength and Young's modulus are achieved, respectively. The presented atomistic details of stress graphitization can provide guidance for further optimizing CNT-matrix interfaces in a more predictive and controllable way for the development of novel CNT/C composites with high performance.}, number={27}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Zhang, Liwen and Kowalik, Malgorzata and Mao, Qian and Damirchi, Behzad and Zhang, Yongyi and Bradford, Philip D. and Li, Qingwen and Duin, Adri C. T. and Zhu, Yuntian T. T.}, year={2023}, month={Jun}, pages={32656–32666} }
 @article{fan_zhou_fang_wang_ma_tsai_zhu_2023, title={Probing the Respective Strengthening Mechanism of High-entropy (CoCrFeNi/CoCrFeNiMn) and Single-principle-element (Cu-4Al) Alloys}, volume={969}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2023.172185}, abstractNote={The strengthening mechanism of high-entropy alloys (CoCrFeNi/CoCrFeNiMn) is investigated and compared with a single-principle-element alloy (Cu-4Al) with similar stacking fault energy. Hall-Petch effect dominates the strain hardening of both alloys during progressive grain refinement to the ultrafine regime. Moreover, the high density of Lomer-Cottrell locks offers unique and extra hardening to ultrafine-grained high-entropy alloys.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Fan, Liwen and Zhou, Jian and Fang, Xiaotian and Wang, Yanfei and Ma, Xiaolong and Tsai, Ming-Hung and Zhu, Yuntian}, year={2023}, month={Dec} }
 @misc{fang_li_wang_ruiz_ma_wang_zhu_schoell_zheng_kaoumi_et al._2022, title={Achieving high hetero-deformation induced (HDI) strengthening and hardening in brass by dual heterostructures}, volume={98}, ISSN={["1005-0302"]}, url={https://doi.org/10.1016/j.jmst.2021.03.088}, DOI={10.1016/j.jmst.2021.03.088}, abstractNote={Heterostructured materials have a superior combination of strength and ductility, due to their ability to produce hetero-deform induced (HDI) strengthening and hardening. Therefore, achieving high HDI strengthening and hardening is the primary goal for designing heterostructures. Here we report a dual heterostructure in brass that consists of the heterogeneous lamella and gradient structure, fabricated by rolling, partial annealing, and rotationally accelerated shot peening (RASP). The dual heterostructures are able to generate extra interfaces of heterogeneity compared to the single heterostructures, which could lead to higher HDI strengthening and hardening, and a more superior combination of strength and ductility. This finding presents a new pathway to designing heterostructures in metallic materials.}, journal={JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY}, author={Fang, X. T. and Li, Z. K. and Wang, Y. F. and Ruiz, M. and Ma, X. L. and Wang, H. Y. and Zhu, Y. and Schoell, R. and Zheng, C. and Kaoumi, D. and et al.}, year={2022}, month={Jan}, pages={244–247} }
 @article{zhang_ma_zhang_bradford_zhu_2021, title={Length-dependent carbon nanotube film structures and mechanical properties}, volume={32}, ISSN={["1361-6528"]}, DOI={10.1088/1361-6528/abef92}, abstractNote={Abstract
               We investigated the microstructures of carbon nanotube (CNT) films and the effect of CNT length on their mechanical performance. 230 μm-, 300 μm-, and 360 μm- long CNTs were grown and used to fabricate CNT films by a winding process. Opposite from the length effect on CNT fibers, it has been found that the mechanical properties of the CNT films decrease with increasing CNT length. Without fiber twisting, short CNTs tend to bundle together tightly by themselves in the film structure, resulting in an enhanced packing density; meanwhile, they also provide a high degree of CNT alignment, which prominently contributes to high mechanical properties of the CNT films. When CNTs are long, they tend to be bent and entangled, which significantly reduce their packing density, impairing the film mechanical behaviors severely. It has also been unveiled that the determinant effect of the CNT alignment on the film mechanical properties is more significant than that of the film packing density. These findings provide guidance on the optimal CNT length when attempting to fabricate high-performance macroscopic CNT assemblies.}, number={26}, journal={NANOTECHNOLOGY}, author={Zhang, Liwen and Ma, Xiaolong and Zhang, Yongyi and Bradford, Philip D. and Zhu, Yuntian T.}, year={2021}, month={Jun} }
 @article{liu_cao_mao_zhou_zhao_jiang_liu_wang_you_zhu_2020, title={Critical microstructures and defects in heterostructured materials and their effects on mechanical properties}, volume={189}, ISSN={["1873-2453"]}, url={https://doi.org/10.1016/j.actamat.2020.03.001}, DOI={10.1016/j.actamat.2020.03.001}, abstractNote={Systematic study was conducted on the microstructures and mechanical properties of nickel samples with two distinct types of heterostructures. The first is featured with coarse-grained lamellae embedded in a matrix consisting of a very high density of dislocation structures. The second is featured with coarse-grained zones embedded in the ultrafine-grained matrix. The second type of heterostructures exhibits better strength and ductility, although it has a smaller average grain size than the first type. The zone boundaries in the second type of heterostructures are less prone to cracking than those in the first type. Intersecting micro-shear-bands formed net-like patterns in the second type of heterostructures during tensile deformation. This is the first ever observation of structural micro-shear-bands in a heterostructured material. It supports the claim that heterostructure promotes the formation of dispersive shear bands. In contrast, a macroscopic shear band formed and caused early failure of the sample with the first type of heterostructures. Our results indicate that well-developed ultrafine/nano grained matrix in heterostructured materials are necessary for preventing crack formation and shear band localization. This should be considered as a key factor for optimizing the mechanical properties of heterostructured materials.}, journal={ACTA MATERIALIA}, author={Liu, Yanfang and Cao, Yang and Mao, Qingzhong and Zhou, Hao and Zhao, Yonghao and Jiang, Wei and Liu, Ying and Wang, Jing Tao and You, Zesheng and Zhu, Yuntian}, year={2020}, month={May}, pages={129–144} }
 @article{wu_zhu_lu_2020, title={Ductility and strain hardening in gradient and lamellar structured materials}, volume={186}, ISSN={["1872-8456"]}, url={https://doi.org/10.1016/j.scriptamat.2020.05.025}, DOI={10.1016/j.scriptamat.2020.05.025}, abstractNote={Low ductility has long been the bottleneck especially at high strength in metallic structured materials due to conventional forest hardening having little to no effect. Hetero-structuring is an emerging strategy producing superior strength and ductility combination. This Viewpoint article delineates mechanisms for strain hardening and plastic deformation in gradient and lamellar structured materials. Both have typical trans-scale grain hierarchy, leading to sharp mechanical incompatibility and consequent strain gradient at hetero-interfaces during plastic deformation. This induces heterogeneous deformation-induced hardening, along with recovered forest hardening, jointly to improve ductility. The heterogeneous deformation-related deformation physics sheds lights on the path to designing novel heterostructures particularly for large ductility at high strength.}, journal={SCRIPTA MATERIALIA}, publisher={Elsevier BV}, author={Wu, Xiaolei and Zhu, Yuntian and Lu, Ke}, year={2020}, month={Sep}, pages={321–325} }
 @article{xiao_chen_wei_liu_yin_hu_zhou_zhu_2021, title={Effect of dislocation configuration on Ag segregation in subgrain boundary of a Mg-Ag alloy}, volume={191}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2020.08.040}, abstractNote={Interfacial segregation has been reported to play a critical role in the thermal-mechanical stability of nanocrystalline Mg alloys. Here we report Ag-segregation-assisted formation of nanocrystalline Mg-Ag alloy with high proportion of sub-grain boundaries during conventional rolling. The segregation structure is determined by dislocation configurations and subsequent strain field and misorientation of the sub-grain boundary. It indicates that the alloying elements, which induce <c+a> dislocations, would help to improve the stability of interfaces.}, journal={SCRIPTA MATERIALIA}, author={Xiao, Lirong and Chen, Xuefei and Wei, Kang and Liu, Yi and Yin, Dongdi and Hu, Zhaohua and Zhou, Hao and Zhu, Yuntian}, year={2021}, month={Jan}, pages={219–224} }
 @article{fang_he_zheng_ma_kaoumi_li_zhu_2020, title={Effect of heterostructure and hetero-deformation induced hardening on the strength and ductility of brass}, volume={186}, ISSN={["1873-2453"]}, url={https://doi.org/10.1016/j.actamat.2020.01.037}, DOI={10.1016/j.actamat.2020.01.037}, abstractNote={Heterostructured materials have been reported to possess superior combinations of strength and ductility, which is attributed to hetero-deformation induced (HDI) strengthening and work hardening. However, the influence of heterostructural parameters on the evolution of HDI stress and mechanical behavior during tensile deformation is not well understood. In this paper, heterostructured brass (Cu–30%Zn) was fabricated by cold rolling and partial annealing, to produce heterostructures with different heterostructural parameters, including domain volume fraction, domain thickness/spacing and domain misorientation. It was found that HDI hardening was dominant when the tensile strain was less than ∼4.5%, while conventional dislocation hardening became more effective at higher strain levels. Quick accumulation of geometrically necessary dislocations was found in the domain boundary regions, leading to high HDI stress. Higher domain misorientation was found more effective in developing HDI hardening. These findings elucidate the effect of heterostructure on strength and ductility, which can help with the design of heterostructured materials for superior mechanical properties.}, journal={ACTA MATERIALIA}, publisher={Elsevier BV}, author={Fang, X. T. and He, G. Z. and Zheng, C. and Ma, X. L. and Kaoumi, D. and Li, Y. S. and Zhu, Y. T.}, year={2020}, month={Mar}, pages={644–655} }
 @article{guo_wang_wang_he_ran_huang_zhu_2020, title={Hetero-deformation induced strengthening and toughening of pure iron with inverse and multi-gradient structures}, volume={782}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2020.139256}, abstractNote={Here an inverse gradient structure (IGS) is processed by induction heat treatment on ultrafine-grained substrate, and a multi-gradient structure (MGS) is gained by surface mechanically peening treatment on IGS material. The grain size distributions of coarse-ultrafine and nanostructure-coarse-ultrafine gradient from surface to interior are identified in IGS and MGS materials, respectively. Gradient structures maintain reasonable elongation and at the same time display 3–4 times higher yield strength as compared with homogeneous coarse-grained counterpart, indicating improved strength-ductility synergy. Moreover, it is found that the fracture of gradient structures depends largely on the high internal stress caused by the heterogeneous deformation of layers.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Guo, F. J. and Wang, Y. F. and Wang, M. S. and He, Q. and Ran, H. and Huang, C. X. and Zhu, Y. T.}, year={2020}, month={Apr} }
 @article{zhu_ameyama_anderson_beyerlein_gao_kim_lavernia_mathaudhu_mughrabi_ritchie_et al._2021, title={Heterostructured materials: superior properties from hetero-zone interaction}, volume={9}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2020.1796836}, abstractNote={ABSTRACT Heterostructured materials are an emerging class of materials with superior performances that are unattainable by their conventional homogeneous counterparts. They consist of heterogeneous zones with dramatic (>100%) variations in mechanical and/or physical properties. The interaction in these hetero-zones produces a synergistic effect where the integrated property exceeds the prediction by the rule-of-mixtures. The heterostructured materials field explores heterostructures to control defect distributions, long-range internal stresses, and nonlinear inter-zone interactions for unprecedented performances. This paper is aimed to provide perspectives on this novel field, describe the state-of-the-art of heterostructured materials, and identify and discuss key issues that deserve additional studies. IMPACT STATEMENT This paper delineates heterostructured materials, which are emerging as a new class of materials with unprecedented properties, new materials science and economic industrial production. GRAPHICAL ABSTRACT}, number={1}, journal={MATERIALS RESEARCH LETTERS}, author={Zhu, Yuntian and Ameyama, Kei and Anderson, Peter M. and Beyerlein, Irene J. and Gao, Huajian and Kim, Hyoung Seop and Lavernia, Enrique and Mathaudhu, Suveen and Mughrabi, Hael and Ritchie, Robert O. and et al.}, year={2021}, month={Jan}, pages={1–31} }
 @article{liu_zhang_chen_huang_xia_tang_zhu_jiang_pan_2020, title={Improving mechanical properties of heterogeneous Mg-Gd alloy laminate via accumulated extrusion bonding}, volume={785}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2020.139324}, abstractNote={In this study, accumulative extrusion bonding (AEB) was used to process Mg–1Gd/Mg–13Gd laminated composites, in which the Mg–13Gd layers had much finer grains than the Mg–1Gd layers. This grain size difference was maintained after 2-pass, but diminished after the 3-pass. The 2-pass composite samples exhibited an excellent combination of ultimate tensile strength (291 MPa), elongation (20.6%) and yield strength (144 MPa), which are much superior than the individual component materials. Moreover, the 2-pass samples also exhibited maximum extra strength and ductility that is higher than what is predicted by the rule-of-mixture. The observed high strength and ductility are mainly attributed to back-stress strengthening and work hardening, respectively. The 2-pass samples exhibited the highest back stress, indicating an optimum laminate thickness for producing the highest back stress hardening. This work provide a new understanding on the design of heterogeneous laminated Mg alloys for improving mechanical properties.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Liu, Shuaishuai and Zhang, Junlei and Chen, Xiang and Huang, Guangsheng and Xia, Dabiao and Tang, Aitao and Zhu, Yuntian and Jiang, Bin and Pan, Fusheng}, year={2020}, month={May} }
 @article{zhang_cao_gao_yang_shu_zhu_sharma_ameyama_zhu_2020, title={Influence of Strain Rate on Mechanical Behaviours of Gradient-Structured Copper}, volume={61}, ISSN={["1347-5320"]}, DOI={10.2320/matertrans.MT-M2019373}, abstractNote={1Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093, China 2Nano and Heterogeneous Materials Center, School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094, China 3Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA 4Department of Mechanical Engineering, Faculty of Science and Engineering, Ritsumeikan University, Kusatsu 525-8577, Japan}, number={4}, journal={MATERIALS TRANSACTIONS}, author={Zhang, Jinxu and Cao, Yang and Gao, Hongliang and Yang, Xu and Shu, Baipo and Zhu, Yuntian T. and Sharma, Bhupendra and Ameyama, Kei and Zhu, Xinkun}, year={2020}, pages={708–717} }
 @article{liu_guo_pan_liao_lavernia_zhu_wei_zhao_2020, title={Microstructural softening induced adiabatic shear banding in Ti-23Nb-0.7Ta-2Zr-O gum metal}, volume={54}, ISSN={["1005-0302"]}, DOI={10.1016/j.jmst.2020.03.042}, abstractNote={Ti-23Nb-0.7Ta-2Zr-O gum metal (GM) is an attractive candidate material for applications that require superior mechanical properties. In our earlier investigation of the GM [1], geometrical softening and the generation of adiabatic shear bands (ASBs) were proposed as primary reasons for the documented anisotropic impact response. In the present study, electron backscattered diffraction (EBSD) analysis reveals two different deformed microstructures, i.e., deformed ultrafine grains (UFGs) and dynamically recrystallized UFGs, formed in the ASBs of GM samples processed by extrusion equal channel angular pressing (ECAP), respectively. Additional calculation of temperature rise during dynamic compression suggests that the above microstructure differences in the ASBs was originated from their different maximum ASB temperatures (608 K for extruded GM and 1159 K for ECAP-processed GM). Moreover, our calculation on the temperature at the onset of ASBs indicates that microstructural softening is the primary cause for the development of ASBs in both extruded GM (321 K) and ECAP-processed GM (331 K).}, journal={JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY}, author={Liu, Silu and Guo, Y. Z. and Pan, Z. L. and Liao, X. Z. and Lavernia, E. J. and Zhu, Y. T. and Wei, Q. M. and Zhao, Yonghao}, year={2020}, month={Oct}, pages={31–39} }
 @article{shi_zhong_li_ren_zheng_shen_yang_peng_hu_zhang_et al._2020, title={Multistage work hardening assisted by multi-type twinning in ultrafine-grained heterostructural eutectic high-entropy alloys}, volume={41}, ISSN={["1873-4103"]}, DOI={10.1016/j.mattod.2020.09.029}, abstractNote={High strength of materials usually comes with low ductility due to the lost or short-lived strain hardening. Here, we uncover a sequentially-activated multistage strain hardening (SMSH) that allows for sustained and effective strain-hardening capability in strong ultrafine-grained eutectic high-entropy alloy (EHEA). Consequently, exceptional ductility is realized in an ultrafine-grained EHEA, accompanied with high ultimate strength. We demonstrate that the SMSH is derived from a coordinated three-level design on structural heterogeneity, grain-size control, and intragranular composition modification, which enables the sequential activation of stress-dependent multiple hardening mechanisms. Furthermore, despite the well-known low twinning propensity due to ultrafine grains and medium-to-high stacking fault energies of prototype EHEAs, our coordinated design sequentially activates three types of deformation twinning to assist this SMSH. This work sheds light on the SMSH effect assisted by multi-type twinning previously unexpected in ultrafine-grained EHEAs, and thereby represents a promising route for improving ductility of high-strength materials.}, journal={MATERIALS TODAY}, author={Shi, Peijian and Zhong, Yunbo and Li, Yi and Ren, Weili and Zheng, Tianxiang and Shen, Zhe and Yang, Bing and Peng, Jianchao and Hu, Pengfei and Zhang, Yong and et al.}, year={2020}, month={Dec}, pages={62–71} }
 @article{wang_huang_li_fang_wang_he_guo_zhu_2020, title={Shear band stability and uniform elongation of gradient structured material: Role of lateral constraint}, volume={37}, ISSN={["2352-4316"]}, DOI={10.1016/j.eml.2020.100686}, abstractNote={Here we report a shear bands-dominated deformation principle for the gradient material composed of two nanostructured gradient layers (NGLs) and a coarse-grained (CG) interior. Multiple shear bands form in the NGL to accommodate the applied strain. The magnitude of uniform elongation depends on shear band stability, and shear band stability is determined by the intensity of constraint between NGL and CG interior. Specifically, the stronger the constraint, the denser and more stable the shear bands dispersed in the NGL, thereby leading to larger uniform elongation. This finding sheds insight into the theoretical basis of harnessing dispersed stable shear bands in heterostructures by optimizing microstructure architecture.}, journal={EXTREME MECHANICS LETTERS}, author={Wang, Yanfei and Huang, Chongxiang and Li, Zhongkai and Fang, Xiaotian and Wang, Mingsai and He, Qiong and Guo, Fengjiao and Zhu, Yuntian}, year={2020}, month={May} }
 @article{li_fang_wang_jiang_wang_liu_wu_zhu_koch_2020, title={Tuning heterostructures with powder metallurgy for high synergistic strengthening and hetero-deformation induced hardening}, volume={777}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2020.139074}, abstractNote={Heterogeneous-lamella-structured Fe-Cu composites were fabricated using powder metallurgy, displaying an inverse “banana” curve between the strength and ductility. The density of domain interfaces and the strength difference between hard and soft domains can be tuned independently, providing a promising way to further study the hetero-deformation induced strengthening mechanisms of heterogeneous-lamella-structures.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Z. K. and Fang, X. T. and Wang, Y. F. and Jiang, P. and Wang, J. J. and Liu, C. M. and Wu, X. L. and Zhu, Y. T. and Koch, C. C.}, year={2020}, month={Mar} }
 @article{gao_lai_cao_hu_xiao_pan_liang_li_sha_liu_et al._2020, title={Ultrastrong low-carbon nanosteel produced by heterostructure and interstitial mediated warm rolling}, volume={6}, ISSN={["2375-2548"]}, DOI={10.1126/sciadv.aba8169}, abstractNote={We break the limit of grain refinement and strength of low-carbon steel by tuning deformation compatibility of heterostructure.}, number={39}, journal={SCIENCE ADVANCES}, author={Gao, Bo and Lai, Qingquan and Cao, Yang and Hu, Rong and Xiao, Lirong and Pan, Zhiyi and Liang, Ningning and Li, Yusheng and Sha, Gang and Liu, Manping and et al.}, year={2020}, month={Sep} }
 @article{ma_li_sun_hou_fang_zhu_koch_2019, title={Achieving Gradient Martensite Structure and Enhanced Mechanical Properties in a Metastable beta Titanium Alloy}, volume={50A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-019-05157-5}, number={5}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Ma, Xinkai and Li, Fuguo and Sun, Zhankun and Hou, Junhua and Fang, Xiaotian and Zhu, Yuntian and Koch, Carl C.}, year={2019}, month={May}, pages={2126–2138} }
 @article{ding_zhao_sun_li_ma_lavernia_zhu_liu_2020, title={Alloying effects on the plasticity of magnesium: comprehensive analysis of influences of all five slip systems}, volume={32}, ISSN={["1361-648X"]}, DOI={10.1088/1361-648X/ab445d}, abstractNote={Low plasticity has been a major issue for the application of Mg alloys. Here, based on the generalized stacking fault energy curves and Arrhenius equation, we systematically study alloying effects on the stacking fault energies and the activation probability of basal and non-basal 〈a〉, and pyramidal 〈c  +  a〉 slip systems in twenty-one Mg alloys. Our results reveal that activation of 〈c  +  a〉 slip systems on pyramidal II plane can significantly improve the plasticity. For example, Ca is found to promote the activation probability of this slip system by one order of magnitude and dramatically improve the plasticity of Mg.}, number={1}, journal={JOURNAL OF PHYSICS-CONDENSED MATTER}, author={Ding, Zhigang and Zhao, Guangxuan and Sun, Hao and Li, Shuang and Ma, Fei and Lavernia, Enrique J. and Zhu, Yuntian and Liu, Wei}, year={2020}, month={Jan} }
 @article{chen_xiao_ding_liu_zhu_wu_2020, title={Atomic segregation at twin boundaries in a Mg-Ag alloy}, volume={178}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2019.11.025}, abstractNote={Segregation of solute atoms at twin boundaries (TBs) plays a critical role in mechanical properties and thermal stability of magnesium alloys. Here, segregation structures at {101¯1}, {101¯2} and {101¯3} TBs are characterized in a Mg-Ag alloy by means of the atomic resolution high-angle annular dark-field technique based on scanning transmission electron microscopy. Of particular finding is the unique complex segregation at {101¯3} TBs, where Ag atoms occupy both substitutional and interstitial sites. By contrast, Ag atoms only substitutionally segregate at {101¯1} and {101¯2} TBs. Calculation simulation of segregation energy and three-dimensional structure of TBs helps understanding of hybrid segregation.}, journal={SCRIPTA MATERIALIA}, author={Chen, X. F. and Xiao, L. R. and Ding, Z. G. and Liu, W. and Zhu, Y. T. and Wu, X. L.}, year={2020}, month={Mar}, pages={193–197} }
 @article{wang_huang_li_guo_he_wang_wu_scattergood_zhu_2020, title={Dense dispersed shear bands in gradient-structured Ni}, volume={124}, ISSN={["1879-2154"]}, DOI={10.1016/j.ijplas.2019.08.012}, abstractNote={During tensile deformation, nanostructured (NS) metals often fail soon after yielding by forming a localized shear band. Here we report the observation of high density of shear bands that are homogeneously dispersed in the NS layer of a gradient Ni sample. These shear bands were nucleated at early elastic/plastic strain stage, reached number saturation at ∼3% strain, and remained arrested by the central coarse-grained (CG) matrix during the entire plastic deformation, resulting in a uniform tensile plasticity comparable to that of CG matrix. The formation of dispersed shear bands was promoted by the elastic/plastic interaction between NS surface layer and CG matrix, and affected by the surface roughness and the hardness variation in the NS surface layer. The width of shear bands remained constant, but the intensity of strain accumulation increased almost linearly with applied tensile strain, suggesting a stable shear banding process. Microstructure examination revealed that the strain in shear bands was accommodated by mechanically driven grain boundary migration and grain coarsening. These results clarify the fundamental questions: why/how does the NS layer supported by CG matrix achieve large uniform elongation? Moreover, the findings demonstrate the possibility of activating dispersed stable shear bands by synthesizing gradient architecture for optimized mechanical performances, i.e., a new strategy for evading the strength-ductility tradeoff in NS metals.}, journal={INTERNATIONAL JOURNAL OF PLASTICITY}, author={Wang, Yanfei and Huang, Chongxiang and Li, Yusheng and Guo, Fengjiao and He, Qiong and Wang, Mingsai and Wu, Xiaolei and Scattergood, Ronald O. and Zhu, Yuntian}, year={2020}, month={Jan}, pages={186–198} }
 @article{chen_li_zhu_yang_2019, title={Enhanced irradiation and corrosion resistance of 316LN stainless steel with high densities of dislocations and twins}, volume={517}, ISSN={["1873-4820"]}, url={https://doi.org/10.1016/j.jnucmat.2019.02.016}, DOI={10.1016/j.jnucmat.2019.02.016}, abstractNote={The irradiation and corrosion damages of nuclear materials have been a major challenge for the nuclear energy industry. Here, rotationally accelerated shot peening was used to improve the radiation and corrosion resistance of 316LN austenitic stainless steel by introducing high densities of dislocations and nanoscale twin boundaries. The dislocations and twins not only impeded the formation of helium bubbles and shear bands during irradiation, but also facilitated the formation of a superior passivation film, which significantly improved its corrosion performance. These observations provide an effective approach for designing irradiation- and corrosion-resistant nuclear materials.}, journal={JOURNAL OF NUCLEAR MATERIALS}, publisher={Elsevier BV}, author={Chen, Xudong and Li, Yusheng and Zhu, Yuntian and Yang, Bin}, year={2019}, month={Apr}, pages={234–240} }
 @article{wang_wang_fang_guo_liu_scattergood_huang_zhu_2019, title={Extra strengthening in a coarse/ultrafine grained laminate: Role of gradient interfaces}, volume={123}, ISSN={["1879-2154"]}, DOI={10.1016/j.ijplas.2019.07.019}, abstractNote={The interfaces introduced in metals by heterostructural design play crucial roles in mechanical behaviors. Here the effect of gradient interfaces on mechanical behavior was investigated in a laminated Cu–30Zn sample composed of coarse-grained and ultrafine-grained layers. Tensile tests revealed a superior strength-ductility synergy with extraordinary strengthening and work hardening. By combining the measurements of height contour and strain distribution using digital image correlation, the development of strain gradient was detected in the near-interface zone during tension, which was caused by the mechanical incompatibilities across interfaces and the synergetic constraint between layers. The intensity of strain gradient in the near-interface zone increased with tensile strain, which was accommodated by the accumulation of geometrically necessary dislocations, thereby resulting in extra back stress and dislocation strengthening.}, journal={INTERNATIONAL JOURNAL OF PLASTICITY}, author={Wang, Y. F. and Wang, M. S. and Fang, X. T. and Guo, F. J. and Liu, H. Q. and Scattergood, R. O. and Huang, C. X. and Zhu, Y. T.}, year={2019}, month={Dec}, pages={196–207} }
 @article{liu_hu_zheng_zhang_ding_liu_zhu_sha_2020, title={Formation of solute nanostructures in an Al-Zn-Mg alloy during long-term natural aging}, volume={821}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2019.153572}, abstractNote={Nature aging (NA) is believed to produce solute nanostructures, including solute clusters and GPI zones in Al–Zn–Mg alloys. Here we report the first observation that GPII (GPη’) zones with an average Zn/Mg ratio near 1.3–1.4 formed in the Al–Zn–Mg alloys during long-term natural aging. High-angle-annular-dark-field scanning transmission electron microscopy and atom probe tomography were used to study the evolution of solute nanostructures during natural aging. Early clusters were found to have a wide spread of Zn/Mg ratios and their number density increased sharply with a dramatic hardening effect during the first month ageing. Further ageing up to 3 months made the Zn/Mg ratios of the solute clusters gradually converge to near 1.2 (GPI zones), but produced no change in the morphology, size distribution and volume fraction of the solute nanostructures, as well as hardness. At room temperature, GPII (GPη’ type) zones formed very slowly and provided stronger hardening effects than early clusters. Importantly, unlike solute-rich clusters, GPI and GPη’ zones are easy to transform into η′ during subsequent artificial ageing, avoiding hardness drop at the early stage of subsequent artificial aging at 120 °C.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Liu, Jizi and Hu, Rong and Zheng, Jialing and Zhang, Yidong and Ding, Zhigang and Liu, Wei and Zhu, Yuntian and Sha, Gang}, year={2020}, month={Apr} }
 @article{chen_huang_liu_han_jiang_tang_zhu_pan_2019, title={Grain refinement and mechanical properties of pure aluminum processed by accumulative extrusion bonding}, volume={29}, ISSN={["2210-3384"]}, DOI={10.1016/S1003-6326(19)64953-8}, abstractNote={Ultrafine-grained aluminum processed by a new severe plastic deformation technique, accumulative extrusion bonding (AEB), was investigated. Microstructural characterization indicated good interfacial bonding and an average grain size of ∼440 nm was obtained after six passes. Tensile testing revealed that the strength reached the maximum value of 195 MPa and the total elongation exceeded 16% after five passes. The hardness was also significantly improved and almost reached saturation after the first pass. SEM fractography of AEB-processed specimens after tensile test showed that failure mode was shear ductile fracture with elongated shallow dimples. Comparison with conventional accumulative roll bonding indicates that this new AEB technique is more effective in refining grain and improving mechanical properties of the specimens.}, number={3}, journal={TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA}, author={Chen, Xiang and Huang, Guang-sheng and Liu, Shuai-shuai and Han, Ting-zhuang and Jiang, Bin and Tang, Ai-tao and Zhu, Yun-tian and Pan, Fu-sheng}, year={2019}, month={Mar}, pages={437–447} }
 @article{li_dai_cao_zhao_zhu_2019, title={Grain size effect on deformation twin thickness in a nanocrystalline metal with low stacking-fault energy}, volume={34}, ISSN={["2044-5326"]}, DOI={10.1557/jmr.2019.194}, abstractNote={Abstract}, number={13}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Li, Yusheng and Dai, Liangjuan and Cao, Yang and Zhao, Yonghao and Zhu, Yuntian}, year={2019}, month={Jul}, pages={2398–2405} }
 @article{wang_huang_he_guo_wang_song_zhu_2019, title={Heterostructure induced dispersive shear bands in heterostructured Cu}, volume={170}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2019.05.036}, abstractNote={Here we report the formation of dispersive shear bands in a heterostructured Cu composed of coarse-grained (CG) and ultrafine-grained (UFG) domains. Microscale digital image correlation revealed that dense shear bands evolved in a stable manner over the whole gauge section. Our observation suggests that the limited strain hardening of UFG domains and deformation heterogeneity promoted shear banding, which is a major deformation mechanism in heterostructured materials. The dispersive shear banding helped with ductility retention.}, journal={SCRIPTA MATERIALIA}, author={Wang, Y. F. and Huang, C. X. and He, Q. and Guo, F. J. and Wang, M. S. and Song, L. Y. and Zhu, Y. T.}, year={2019}, month={Sep}, pages={76–80} }
 @article{chen_li_zhu_bai_yang_2019, title={Improved corrosion resistance of 316LN stainless steel performed by rotationally accelerated shot peening}, volume={481}, ISSN={["1873-5584"]}, DOI={10.1016/j.apsusc.2019.03.256}, abstractNote={Rotationally accelerated shot peening (RASP) technology was used to produce nanocrystallines and twins on the surface of 316LN stainless steel. Electrochemical corrosion experiments were carried out on the RASP-processed 316LN SS specimens in the 3.5 wt% NaCl solution. Improved passivity and better electronic properties of passive films were observed on the RASP-processed specimens. The experimental results showed that the structure with nanocrystallines and a high density of twins produced by the RASP process can provide more nucleation sites, adhesion work and homogeneous capillary force to improve the uniformity and compactness of the passive film, resulting in a better corrosion resistance.}, journal={APPLIED SURFACE SCIENCE}, author={Chen, Xudong and Li, Yusheng and Zhu, Yuntian and Bai, Yakui and Yang, Bin}, year={2019}, month={Jul}, pages={1305–1312} }
 @article{nie_lu_huang_ma_zhou_chen_chen_yang_cao_liu_et al._2020, title={Improving the high-temperature ductility of Al composites by tailoring the nanoparticle network}, volume={9}, ISSN={["2589-1529"]}, DOI={10.1016/j.mtla.2019.100523}, abstractNote={Al-matrix composites with networked ceramic nanoparticles have been reported to possess high thermal stability, but their low ductility at high temperatures limits their wide applications. In this study, rotary swaging (RS) was used to modify the network of AlNp nanoparticles for optimizing the high temperature tensile properties of Al matrix composites. The RS treatment was found to disperse the network structure of AlNp particles to some extent and to refine the grains of Al matrix, which resulted in high strain hardening and strain rate sensitivity. This not only improved the thermal stability but also increased the uniform elongation from 0.99% to 2.1% at 350°C. This work provides a new pathway for tailoring the nanoparticle architecture to obtain a desirable strength-ductility synergy for metal matrix composites.}, journal={MATERIALIA}, author={Nie, Jinfeng and Lu, Fenghua and Huang, Zhaowen and Ma, Xia and Zhou, Hao and Chen, Cai and Chen, Xiang and Yang, Huabing and Cao, Yang and Liu, Xiangfa and et al.}, year={2020}, month={Mar} }
 @article{zhou_huang_sha_xiao_ma_hoeppel_goeken_wu_ameyama_han_et al._2019, title={In-situ observation of dislocation dynamics near heterostructured interfaces}, volume={7}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2019.1616330}, abstractNote={ABSTRACT There has been a long-standing controversy on how dislocations interact with interfaces. Here we report in-situ observations that in a Cu–brass heterostructured TEM film Frank–Read sources are the primary dislocation sources. They were dynamically formed and deactivated throughout the deformation in grain interior, which has never been reported before. This observation indicates that strain gradient near interfaces cannot be quantitatively related to the density gradient of geometrically necessary dislocations, and it was primarily produced by Frank–Read source gradient instead of dislocation pile-ups. These findings provide new insights on how to design heterostructured interfaces to enhance mechanical properties. GRAPHICAL ABSTRACT}, number={9}, journal={MATERIALS RESEARCH LETTERS}, author={Zhou, Hao and Huang, Chongxiang and Sha, Xuechao and Xiao, Lirong and Ma, Xiaolong and Hoeppel, Heinz Werner and Goeken, Mathias and Wu, Xiaolei and Ameyama, Kei and Han, Xiaodong and et al.}, year={2019}, pages={376–382} }
 @article{fang_he_ruiz_zheng_wang_li_zhu_2019, title={Influence of annealing parameters on the mechanical properties of heterogeneous lamella structured 5083 aluminum alloy}, volume={9}, ISSN={["2410-3535"]}, DOI={10.22226/2410-3535-2019-4-556-560}, abstractNote={1Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695, USA 2Department of Microsystems — IMS, Faculty of Technology, Natural Sciences and Maritime Sciences, University of South-Eastern Norway, Postboks 235, 3603, Kongsberg, Norway 3Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695, USA 4School of Aeronautics and Astronautics, Sichuan University, Chengdu, 610065, China 5Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China 6Nano and Heterogeneous Structural Materials Center, Nanjing University of Science and Technology, Nanjing, 210094, China}, number={4}, journal={LETTERS ON MATERIALS}, author={Fang, X. T. and He, G. Z. and Ruiz, M. and Zheng, C. and Wang, Y. F. and Li, Z. K. and Zhu, Y. T.}, year={2019}, month={Dec}, pages={556–560} }
 @article{chen_li_zhu_chen_yang_2020, title={Layer-by-layer corrosion behavior of 316LN stainless steel with a gradient-nanostructured surface}, volume={110}, ISSN={["1873-1902"]}, DOI={10.1016/j.elecom.2019.106642}, abstractNote={A 316LN stainless steel with a gradient-nanostructured surface layer was fabricated by rotationally accelerated shot peening (RASP). The thickness of this gradient layer was about 210 μm. Layer-by-layer electrochemical experiments confirmed that the layer of the gradient steel with the best corrosion resistance is found at a distance of 110 μm from the surface. The nanostructures and pits generated by RASP produced two opposing effects on its corrosion resistance: the nanocrystals and nano-twins facilitate the formation of a thick, compact passive film which resists corrosion, whereas the pits tend to destroy it. The passive films formed on the pits and on the smoothly nanostructured areas were 5.5 nm and 13.9 nm thick, respectively.}, journal={ELECTROCHEMISTRY COMMUNICATIONS}, author={Chen, Xudong and Li, Yusheng and Zhu, Yuntian and Chen, Yuefeng and Yang, Bin}, year={2020}, month={Jan} }
 @article{liu_cao_zhou_chen_liu_xiao_huan_zhao_zhu_2020, title={Mechanical Properties and Microstructures of Commercial-Purity Aluminum Processed by Rotational Accelerated Shot Peening Plus Cold Rolling}, volume={22}, ISSN={["1527-2648"]}, DOI={10.1002/adem.201900478}, abstractNote={Commercial‐purity aluminum with 99.7% purity is processed by rotational accelerated shot peening (RASP) and cold‐rolling. RASP samples are rolled at room temperature to a thickness reduction of 20% and 30%, for the purpose of surface roughness reduction and strengthening. Detailed microstructural characterization and hardness tests reveal that cold‐rolling cause grain growth at the surfaces of RASP samples from ≈472 to ≈1000 nm. Moderate cold‐rolling is effective in smoothing the surface of RASP samples, while improving strength and maintaining ductility. However, cold‐rolling to more than 30% thickness reduction eventually diminishes the gradient nanostructure. During cold‐rolling of RASP samples, a transition zone with strong strain incompatibility is noticed by a sharp rise in hardness at some point of the hardness‐distribution curve from the surface to the core of the sample. This transition zone is a result of quick generation of geometrically necessary dislocations. Although the transition zone with strong strain incompatibility is short‐lived, it is anticipated to be common among gradient‐nanostructured materials under cold‐rolling condition.}, number={1}, journal={ADVANCED ENGINEERING MATERIALS}, author={Liu, Yanfang and Cao, Yang and Zhou, Hao and Chen, Xuefei and Liu, Ying and Xiao, Lirong and Huan, Xiaowei and Zhao, Yonghao and Zhu, Yuntian}, year={2020}, month={Jan} }
 @article{zhao_bingert_topping_sun_liao_zhu_lavernia_2020, title={Mechanical behavior, deformation mechanism and microstructure evolutions of ultrafine-grained Al during recovery via annealing}, volume={772}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2019.138706}, abstractNote={Ultrafine grained (UFG) metals and alloys typically exhibit mechanical and thermal instabilities, partially due to the high density of lattice defects, which limits their engineering applications. Annealing represents a simple and effective way to regain strain hardening, ductility and thermal stability, and stabilize the UFG structures. In this study, we systematically investigated the mechanical behavior, microstructural evolution, fracture and deformation mechanisms of UFG Al during recovery via low-temperature annealing. More specifically we report that low-temperature annealing at 250 °C for 20 min increased the ultimate tensile strength by 10% from 190 to 208 MPa and tensile ductility by 50% from 4.5 to 6.8% without any changes in yield strength (180 MPa). Microstructural analyses indicate that the annealing increased the average grain size from 740 to 840 nm, dislocation density decreased from 5 × 1014 m-2 to 1 × 1014 m-2, while the nature of the grain boundaries and associated precipitated phases remained unchanged. Moreover, annealing led to modification of statistically stored dislocations into low-energy dislocation walls (sub-grain boundaries). Results from the fracture surface morphology indicated that the enhanced ductility of the annealed sample was related to the activation of numerous homogeneous micro shear bands, which were controlled by cooperative grain boundary sliding. These observations suggest that the dislocation walls formed during recovery promoted the formation of micro shear bands/cooperative grain boundary sliding and thereby enhanced the ductility.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Zhao, Y. H. and Bingert, J. F. and Topping, T. D. and Sun, P. L. and Liao, X. Z. and Zhu, Y. T. and Lavernia, E. J.}, year={2020}, month={Jan} }
 @article{jiang_zhou_cao_nie_li_zhao_kawasaki_langdon_zhu_2020, title={On the Heterogeneity of Local Shear Strain Induced by High-Pressure Torsion}, volume={22}, ISSN={["1527-2648"]}, DOI={10.1002/adem.201900477}, abstractNote={A ductile duplex stainless steel consisting of a ferrite phase and an austenitic phase is chosen as a model material to investigate the development of shear strain patterns under high‐pressure torsion. Systematic analysis on the macroscopic and microscopic heterogeneities of local shear strain reveals that complex shear patterns can be developed only above a high strain level where the grain sizes are already refined to a steady state. It is concluded that grain boundary‐mediated deformation mechanisms provide sufficient freedom for reshaping the austenite phase domains, and thus the intrinsic factor required for the formation of these complicated shear patterns is well‐developed ultrafine grains and/or nanograins.}, number={1}, journal={ADVANCED ENGINEERING MATERIALS}, author={Jiang, Wei and Zhou, Hao and Cao, Yang and Nie, Jinfeng and Li, Yusheng and Zhao, Yonghao and Kawasaki, Megumi and Langdon, Terence G. and Zhu, Yuntian}, year={2020}, month={Jan} }
 @article{huang_wang_wang_song_li_gao_huang_zhu_2019, title={Optimizing the strength, ductility and electrical conductivity of a Cu-Cr-Zr alloy by rotary swaging and aging treatment}, volume={746}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2019.01.002}, abstractNote={A high performance Cu-Cr-Zr alloy with an ultimate tensile strength of 612 MPa, a uniform elongation of 5% and an electrical conductivity of 84.7% IACS was achieved by the severe rotary swaging and two-step peak-aging treatment. A perfect ultrafine grained microstructure with uniformly distributed nano-precipitates was identified to be responsible for the excellent properties of the studied alloy. The proposed method of rotary swaging in combination with the two-step aging treatment shows good potential for producing the high performance Cu-Cr-Zr alloy, which can not only fulfill the industrial requirement of strength and electrical conductivity, but also is suitable for mass production.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Huang, A. H. and Wang, Y. F. and Wang, M. S. and Song, L. Y. and Li, Y. S. and Gao, L. and Huang, C. X. and Zhu, Y. T.}, year={2019}, month={Feb}, pages={211–216} }
 @article{zhu_wu_2019, title={Perspective on hetero-deformation induced (HDI) hardening and back stress}, volume={7}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2019.1616331}, abstractNote={ABSTRACT Heterostructured materials have been reported as a new class of materials with superior mechanical properties, which was attributed to the development of back stress. There are numerous reports on back stress theories and measurements with no consensus. Back stress is developed in soft domains to offset the applied stress, making them appear stronger, while forward stress is developed to make hard domains appear weaker. The extra hardening in heterostructured materials is resulted from interactions between back stresses and forward stresses, and should be described as hetero-deformation induced (HDI) hardening and the measured ‘back stress’ should be renamed HDI stress. GRAPHICAL ABSTRACT IMPACT STATEMENT The ‘back stress’ hardening in the literature can be described more accurately as hetero-deformation induced (HDI) hardening and the measured ‘back stress’ should be renamed HDI stress.}, number={10}, journal={MATERIALS RESEARCH LETTERS}, author={Zhu, Yuntian and Wu, Xiaolei}, year={2019}, pages={393–398} }
 @article{sun_ding_zhang_zhou_li_lavernia_zhu_liu_2019, title={Predicting the formation of < c}, volume={7}, ISSN={["2589-1529"]}, DOI={10.1016/j.mtla.2019.100352}, abstractNote={The presence of alloying elements in magnesium (Mg) can activate pyramidal <c + a> slip systems and thereby improve the plasticity of Mg at room temperature. In this study, we predict the effect of alloying elements on the formation of <c + a> dislocations based on a synergistic effect stemming from both leading and trailing partial dislocations. Our calculations demonstrate that the addition of rare earths, Li, Ca, and Sn significantly lowers at least one energy barrier in pure Mg, and ultimately promotes the formation of the pyramidal I and/or pyramidal II slip systems. The reduced energy barriers are mainly attributed to the local lattice distortions and charge redistribution induced by alloying atoms. These findings provide important insight into the influence of alloying on the formation of <c + a> dislocations, and may ultimately facilitate the development of a framework to design high-plasticity Mg alloys.}, journal={MATERIALIA}, author={Sun, Hao and Ding, Zhigang and Zhang, Dalong and Zhou, Hao and Li, Shuang and Lavernia, Enrique J. and Zhu, Yuntian and Liu, Wei}, year={2019}, month={Sep} }
 @article{yang_chen_zhu_li_2019, series={Minerals Metals & Materials Series}, title={Radiation and Corrosion Resistances of 316LN Austenitic Stainless Steel by Rotationally Accelerated Shot Peening}, ISBN={2367-1181}, DOI={10.1007/978-3-030-05861-6_119}, abstractNote={A rotationally accelerated shot peening (RASP) technique was used to improve the radiation and corrosionCorrosion resistances of 316LN austenitic stainless steelAustenitic stainless steel (316LN SS). The experimental results indicated that high density nanoscale twin boundaries (NTBs) were introduced in the steelSteel after the RASP. These boundaries were found not only beneficial to enhance radiation resistance but improve the corrosion resistanceCorrosion Resistance of the steelSteel . Radiation experiments showed the average size of helium bubbles and unstable shear bands were restrained in the RASPed 316LN SS comparing to those tested in the as-received 316LN SS samples. The electrochemical test results revealed the critical pittingPitting potential and passive film resistance value of the steelSteel increased after treated by the RASP. These results shed light on radiation and corrosionCorrosion resistances robust developments in advanced nuclear materials.}, journal={TMS 2019 148TH ANNUAL MEETING & EXHIBITION SUPPLEMENTAL PROCEEDINGS}, author={Yang, Bin and Chen, Xudong and Zhu, Yuntian and Li, Yusheng}, year={2019}, pages={1251–1260}, collection={Minerals Metals & Materials Series} }
 @article{yang_li_jiang_yuan_wang_zhu_wu_2019, title={Residual stress provides significant strengthening and ductility in gradient structured materials}, volume={7}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2019.1635537}, abstractNote={ABSTRACT Residual stress exists extensively in biological and engineering structures. Here we report that residual stress can be engineered to significantly enhance the strength and ductility of gradient materials. In-situ synchrotron experiments revealed that the strongest strain hardening occurred in the layer with the highest compressive residual stress in a gradient structure. This layer remained elastic longer than adjacent layers during tension, producing high hetero-deformation induced stress to increase strength and enhancing work hardening even after the disappearance of the compressive stress to increase ductility. This finding provides a new paradigm for designing gradient structures for superior mechanical properties. IMPACT STATEMENT We show that compressive residual stress layer in SMAT-processed gradient material produces hetero-deformation induced hardening, which played a major role in improving strength and ductility. GRAPHICAL ABSTRACT}, number={11}, journal={MATERIALS RESEARCH LETTERS}, author={Yang, Mu-Xin and Li, Run-Guang and Jiang, Ping and Yuan, Fu-Ping and Wang, Yan-Dong and Zhu, Yun-Tian and Wu, Xiao-Lei}, year={2019}, pages={433–438} }
 @article{hasan_liu_an_gu_song_cao_li_zhu_liao_2019, title={Simultaneously enhancing strength and ductility of a high-entropy alloy via gradient hierarchical microstructures}, volume={123}, ISSN={["1879-2154"]}, DOI={10.1016/j.ijplas.2019.07.017}, abstractNote={Although many high-entropy alloys (HEAs) possess excellent mechanical properties, they are not exempt from the common dilemma of strength–ductility trade-off in most cases, which limits their potential applications. Herein, rotationally accelerated shot peening was used to introduce different gradient hierarchical microstructures, including gradients in twin and dislocation densities, and hierarchical nanotwin, into a CoCrFeNiMn HEA by adjusting the processing parameters. The resulting gradient structures and their effect on hardening behaviour and mechanical properties were systematically explored. Quantitative analysis indicates that deformation twinning, including hierarchical nanotwinning could be more important than dislocation slip in terms of their contribution to hardness and strain hardening capability, depending on the gradient structure profile. It was found that simultaneous improvement of strength and ductility can be achieved in a gradient structure with a thin deformed layer and an undeformed core. Based on our experimental results, we propose that a gradient structure with a largest possible strength difference between the surface layer and the undeformed core would maximize the strength–ductility synergy.}, journal={INTERNATIONAL JOURNAL OF PLASTICITY}, author={Hasan, M. N. and Liu, Y. F. and An, X. H. and Gu, J. and Song, M. and Cao, Y. and Li, Y. S. and Zhu, Y. T. and Liao, X. Z.}, year={2019}, month={Dec}, pages={178–195} }
 @article{xiao_chen_cao_zhou_ma_yin_ye_han_zhu_2020, title={Solute segregation assisted nanocrystallization of a cold-rolled Mg-Ag alloy during annealing}, volume={177}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2019.10.012}, abstractNote={Refining grains to nanoscale has been a challenge, especially for materials with low-melting points and poor ductility, such as Mg alloys. Here we report a novel mechanism of nanocrystallization assisted by solute segregation, by which a nanocrystalline Mg-Ag alloy was produced by moderate cold rolling (∼55% strain) followed by low-temperature annealing. Specifically, during cold rolling non-basal 〈c + a〉 dislocations were activated to form dislocation cells walls, which were pinned by Ag segregation, and transformed into boundaries of nanocrystalline grains during annealing.}, journal={SCRIPTA MATERIALIA}, author={Xiao, L. R. and Chen, X. F. and Cao, Y. and Zhou, H. and Ma, X. L. and Yin, D. D. and Ye, B. and Han, X. D. and Zhu, Y. T.}, year={2020}, month={Mar}, pages={69–73} }
 @article{zhao_zhang_huang_zou_liu_liang_yu_pan_zhu_miao_et al._2018, title={A comparison of the twisted and untwisted structures for one-dimensional carbon nanotube assemblies}, volume={146}, ISSN={0264-1275}, url={http://dx.doi.org/10.1016/J.MATDES.2018.02.068}, DOI={10.1016/J.MATDES.2018.02.068}, abstractNote={The way how carbon nanotubes (CNTs) are assembled together determines the utilization efficiency of mechanical property in their macroscopic assembly materials. For one-dimensional (1D) assemblies, CNTs are often assembled under drawing and twisting into a fiber structure with a twist angle. In this study, an untwisted 1D assembly, CNT strip, is introduced, inside which the CNTs are not only aligned but also overall parallel to strip axis. Due to the shielding effect of the twisted fiber surface, the interior of CNT fiber is loosely packed, and the fiber is more stretchable and hard to become stiff. On the contrary, CNT strip with high straightness or undirectionality can utilize the CNT's mechanical property much more efficiently, as reflected by its higher strength and modulus. These insights can guide different applications of CNT fibers and strips in textile.}, journal={Materials & Design}, publisher={Elsevier BV}, author={Zhao, Jingna and Zhang, Xiaohua and Huang, Yuyao and Zou, Jingyun and Liu, Tong and Liang, Ningning and Yu, Fapeng and Pan, Zhijuan and Zhu, Yuntian and Miao, Menghe and et al.}, year={2018}, month={May}, pages={20–27} }
 @article{yu_zhao_li_li_zhu_2018, title={A novel approach to align carbon nanotubes via water-assisted shear stretching}, volume={164}, ISSN={["1879-1050"]}, url={https://doi.org/10.1016/j.compscitech.2018.05.028}, DOI={10.1016/j.compscitech.2018.05.028}, abstractNote={Floating catalyst chemical vapor deposition (FCCVD) can produce buckypaper, a kind of CNT film, at large-scale with low cost. However, individual CNTs in the buckypaper are mostly randomly oriented, which significantly limits their electrical and mechanical properties. Here we report an innovative approach, water-assisted shear stretching (WASS), which can significantly improve CNT alignments and consequently enhance the electrical and mechanical properties. In addition, we define a unique “alignment factor” to quantify the alignment degree, and to estimate the effect of alignment on the mechanical and electrical properties of CNT assemblies. The high mechanical strength and excellent electrical conductivity of the WASS-processed buckypaper enhance their potential for applications in new electronic technologies and high-strength lightweight aerospace structures.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Yu, Yingying and Zhao, Changhao and Li, Qingwen and Li, Jianying and Zhu, Yuntian}, year={2018}, month={Aug}, pages={1–7} }
 @article{college_zhu_2018, title={Alleviating surface tensile stress in e-beam treated tool steels by cryogenic treatment}, volume={722}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2018.03.036}, abstractNote={Electron beam (e-beam) treatment of tool steel surfaces has been available for several decades as an approach to create hard surface layers on tool steels. The e-beam process produces ultrafine grain sizes through ultra-rapid cooling of the melt layer, which helps with improving wear resistance to increase the service life of tools. However, its implementation in many applications has been limited by the accompanying residual tensile stresses in the surface layer, which is undesirable and may lead to premature fracture. Here we report the utilization of cryogenic freezing after e-beam treatment to reduce the residual tensile stress. The e-beamed specimen contained high levels of retained austenite in the surface layer. The cryogenic treatment converted the retained austenite into martensite, and the corresponding volume expansion reduced the peak tensile residual stress by 28%, which makes it a promising method to expand the applications of e-beamed tool steel.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={College, David A. and Zhu, Yuntian}, year={2018}, month={Apr}, pages={167–172} }
 @article{zhu_2018, title={Catch twin nucleation in action at atomic scale}, volume={61}, ISSN={2095-8226 2199-4501}, url={http://dx.doi.org/10.1007/S40843-018-9212-7}, DOI={10.1007/S40843-018-9212-7}, number={7}, journal={Science China Materials}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian}, year={2018}, month={Jan}, pages={1019–1020} }
 @article{zhu_wu_2018, title={Ductility and plasticity of nanostructured metals: differences and issues}, volume={2}, ISSN={2588-8420}, url={http://dx.doi.org/10.1016/J.MTNANO.2018.09.004}, DOI={10.1016/J.MTNANO.2018.09.004}, abstractNote={Ductility is one of the most important mechanical properties for metallic structural materials. It is measured as the elongation to failure of a sample during standard uniaxial tensile tests. This is problematic and often leads to gross overestimation for nanostructured metals, for which non-standard small samples are typically used. Uniform elongation is a better measure of ductility for small samples because they are less sensitive to sample size. By definition, ductility can be considered as tensile plasticity, but it is often confused with plasticity. In principle, ductility is largely governed by strain hardening rate, which is in turn significantly affected by microstructure, whereas plasticity is primarily controlled by crystal structure or the number of available slip systems to accommodate plastic deformation. In practice, ductility is important for preventing catastrophic failure of structural components during service, whereas plasticity is critical for shaping and forming metals into desired shape and geometry to make structural components. Nanostructured metals typically have high plasticity, but low ductility, due to their low strain hardening capability. Increasing strain hardening rate via modifying microstructure is the primary route to improving ductility.}, journal={Materials Today Nano}, publisher={Elsevier BV}, author={Zhu, Y.T. and Wu, X.L.}, year={2018}, month={Jun}, pages={15–20} }
 @article{yuan_yan_sun_zhou_zhu_wu_2019, title={Ductility by shear band delocalization in the nano-layer of gradient structure}, volume={7}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2018.1546238}, abstractNote={ABSTRACT Nanostructured (NS) metals typically fail soon after yielding, starting with the formation of narrow shear bands. Here we report the observation of shear band delocalization in gradient metals. Shear bands were nucleated and delocalized in the NS layers by propagating along the gage length soon after yielding, converting the shear band into a localized strain zone (LSZ). Synergistic work hardening was developed in the LSZ by regaining dislocation hardening capability, and by back-stress hardening from the strain gradients in the axial and depth directions, which helped with enhancing global ductility. GRAPHICAL ABSTRACT}, number={1}, journal={MATERIALS RESEARCH LETTERS}, author={Yuan, Fuping and Yan, Dingshun and Sun, Jiangda and Zhou, Lingling and Zhu, Yuntian and Wu, Xiaolei}, year={2019}, pages={12–17} }
 @article{fu_zhang_meng_shu_zhu_zhu_2018, title={Effect of strain rate on mechanical properties of Cu/Ni multilayered composites processed by electrodeposition}, volume={726}, ISSN={["1873-4936"]}, url={https://doi.org/10.1016/j.msea.2018.04.076}, DOI={10.1016/j.msea.2018.04.076}, abstractNote={Mechanical properties of Cu/Ni multilayered composites processed by electrodeposition were investigated by tensile tests at different strain rates in the range of 5 × 10−5 to 5 × 10−2 s−1 at room temperature. With increasing strain rates, the strength and ductility of Cu/Ni multilayered composites increased simultaneously, while their strain rate sensitivity also increased, which is very different from the constituent pure Cu and Ni. The back-stress caused by the Cu/Ni layer interfaces also increased with strain rate. Strong back-stress work hardening is observed, which is the main reason for the observed good ductility.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, publisher={Elsevier BV}, author={Fu, Zhengrong and Zhang, Zheng and Meng, Lifang and Shu, Baipo and Zhu, Yuntian and Zhu, Xinkun}, year={2018}, month={May}, pages={154–159} }
 @article{huang_jin_zhou_li_cao_zhu_2019, title={Evolution of twinning systems and variants during sequential twinning in cryo-rolled titanium}, volume={112}, ISSN={0749-6419}, url={http://dx.doi.org/10.1016/J.IJPLAS.2018.08.008}, DOI={10.1016/J.IJPLAS.2018.08.008}, abstractNote={On the basis of the order in which twinning occurs, twins are termed primary, secondary, and tertiary. In HCP materials, compression twins (CT) and extension twins (ET) are observed to form alternatively during sequential twinning. However, selections of twinning systems and variants are not yet fully understood. Both ET→CT→ET and CT→ET→CT sequences have been reported in literatures. Here we conduct a systematic and statistical study on the evolutions of twinning sequences and variants during cryogenic rolling of Ti. Both twinning sequences are observed in the same sample. Current statistical results indicate the selections of the twinning sequence and variants are governed by the following criteria: (1) the twinning sequence in an individual grain depends on its initial orientation; (2) the twin variant selection is mainly governed by the Schmid's law, although a few non-Schmid twins are observed along the short axis of the parent grains. These criteria are thought applicable to other HCP metallic materials.}, journal={International Journal of Plasticity}, publisher={Elsevier BV}, author={Huang, Z.W. and Jin, S.B. and Zhou, H. and Li, Y.S. and Cao, Y. and Zhu, Y.T.}, year={2019}, month={Jan}, pages={52–67} }
 @article{liu_yuan_zhu_wu_2018, title={Extraordinary Bauschinger effect in gradient structured copper}, volume={150}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2018.03.007}, abstractNote={Bauschinger effect is a well-known phenomenon, in which the tensile stress is higher than the reverse compressive stress. Here we report that the gradient structured copper exhibits an extraordinarily large Bauschinger effect. We propose to use the reverse yield softening, Δσb, as a quantitative parameter to represent the Bauschinger effect. Δσb evolves in the same trend as the back stress with pre-strain, and can be used to evaluate the effectiveness of a heterostructure in producing back stress for superior mechanical properties.}, journal={SCRIPTA MATERIALIA}, author={Liu, Xiaolong and Yuan, Fuping and Zhu, Yuntian and Wu, Xiaolei}, year={2018}, month={Jun}, pages={57–60} }
 @article{han_huang_deng_wang_jiang_tang_zhu_pan_2018, title={Grain refining and mechanical properties of AZ31 alloy processed by accumulated extrusion bonding}, volume={745}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2018.02.248}, abstractNote={In order to improve the strength and ductility of AZ31 magnesium alloy thin sheet with thickness of 1.5 mm, an accumulated extrusion bonding (AEB) process was conducted for 1 and 2 passes at 473 K. Microstructure evolution and mechanical properties were subsequently investigated. The results showed that the interface bonded successfully with a good bonding quality due to the large strain induced by AEB process. {10–12} tensile twinning dominated the deformation at the initial stage of extrusion. As the strain increasing, dynamic recrystallization (DRX) occurred and dominated the further deformation. A fully DRXed microstructure was observed in the sizing band and the average grain size was significantly reduced to ∼1.4 μm. Grain growth occurred after the extruded sheet exited from extrusion die. AZ31 alloy sheet after by 1 pass AEB process exhibited a double-peak texture with the basal poles inclined from normal direction (ND) towards extrusion direction (ED) and showed a similar texture intensity to as-received sample. Due to the grain refinement strengthening, the AEB processed sample exhibited better comprehensive mechanical properties with a higher yield strength (169 MPa vs. 145 MPa), ultimate tensile strength (336 MPa vs. 385 MPa) and fracture elongation (24.9% vs. 28.0%) at room temperature. However, for the 2 passes extruded sample, the microstructure evolution and mechanical properties showed a similar characteristic to that of first pass sample. This indicated that increase in the number of AEB pass had no more effect on the grain refining and improving the mechanical properties.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Han, Tingzhuang and Huang, Guangsheng and Deng, Qianyuan and Wang, Guangang and Jiang, Bin and Tang, Aitao and Zhu, Yuntian and Pan, Fusheng}, year={2018}, month={May}, pages={599–608} }
 @article{liang_zhao_li_topping_zhu_valiev_lavernia_2018, title={Influence of microstructure on thermal stability of ultrafine-grained Cu processed by equal channel angular pressing}, volume={53}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-018-2548-1}, number={18}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Liang, Ningning and Zhao, Yonghao and Li, Y. and Topping, T. and Zhu, Yuntian and Valiev, R. Z. and Lavernia, E. J.}, year={2018}, month={Sep}, pages={13173–13185} }
 @article{huang_wang_ma_yin_höppel_göken_wu_gao_zhu_2018, title={Interface affected zone for optimal strength and ductility in heterogeneous laminate}, volume={21}, ISSN={1369-7021}, url={http://dx.doi.org/10.1016/J.MATTOD.2018.03.006}, DOI={10.1016/J.MATTOD.2018.03.006}, abstractNote={Interfaces have been reported to significantly strengthen and toughen metallic materials. However, there has been a long-standing question on whether interface-affected-zone (IAZ) exists, and how it might behave. Here we report in situ high-resolution strain mapping near interfaces in a copper–bronze heterogeneous laminate, which revealed the existence of IAZs. Defined as the zone with strain gradient, the IAZ was found to form by the dislocations emitted from the interface. The IAZ width remained largely constant with a magnitude of a few micrometers with increasing applied strain. Interfaces produced both back stress strengthening and work hardening, which led to both higher strength and higher ductility with decreasing interface spacing until adjacent IAZs started to overlap, after which a tradeoff between strength and ductility occurred, indicating the existence of an optimum interface spacing for the best mechanical properties. These findings are expected to help with designing laminates and other heterogeneous metals and alloys for superior mechanical properties.}, number={7}, journal={Materials Today}, publisher={Elsevier BV}, author={Huang, C.X. and Wang, Y.F. and Ma, X.L. and Yin, S. and Höppel, H.W. and Göken, M. and Wu, X.L. and Gao, H.J. and Zhu, Y.T.}, year={2018}, month={Sep}, pages={713–719} }
 @article{zou_liu_zhao_hou_liu_zhang_zhao_zhu_li_2018, title={Ni Nanobuffer Layer Provides Light-Weight CNT/Cu Fibers with Superior Robustness, Conductivity, and Ampacity}, volume={10}, ISSN={["1944-8244"]}, DOI={10.1021/acsami.7b19012}, abstractNote={Carbon nanotube (CNT) fiber has not shown its advantage as next-generation light-weight conductor due to the large contact resistance between CNTs, as reflected by its low conductivity and ampacity. Coating CNT fiber with a metal layer like Cu has become an effective solution to this problem. However, the weak CNT-Cu interfacial bonding significantly limits the mechanical and electrical performances. Here, we report that a strong CNT-Cu interface can be formed by introducing a Ni nanobuffer layer before depositing the Cu layer. The Ni nanobuffer layer remarkably promotes the load and heat transfer efficiencies between the CNT fiber and Cu layer and improves the quality of the deposited Cu layer. As a result, the new composite fiber with a 2 μm thick Cu layer can exhibit a superhigh effective strength >800 MPa, electrical conductivity >2 × 107 S/m, and ampacity >1 × 105 A/cm2. The composite fiber can also sustain 10 000 times of bending and continuously work for 100 h at 90% ampacity.}, number={9}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Zou, Jingyun and Liu, Dandan and Zhao, Jingna and Hou, Ligan and Liu, Tong and Zhang, Xiaohua and Zhao, Yonghao and Zhu, Yuntian T. and Li, Qingwen}, year={2018}, month={Mar}, pages={8197–8204} }
 @article{ding_liu_sun_li_zhang_zhao_lavernia_zhu_2018, title={Origins and dissociation of pyramidal <c + a> dislocations in magnesium and its alloys}, volume={146}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2017.12.049}, abstractNote={Alloying magnesium (Mg) with rare earth elements such as yttrium (Y) has been reported to activate the pyramidal <c + a> slip systems and improve the plasticity of Mg at room temperature. However, the origins of such dislocations and their dissociation mechanisms remain poorly understood. Here, we systematically investigate these mechanisms using dispersion-inclusive density-functional theory, in combination with molecular dynamics simulations. We find that <c + a> dislocations form more readily on the pyramidal I plane than on the pyramidal II plane in Mg. The addition of Y atoms in Mg facilitates the dissociation of <c + a> dislocations on pyramidal II, leading to the easier formation of the pyramidal II than pyramidal I in Mg-Y alloy. Importantly, in pyramidal II slip plane, a flat potential-energy surface (PES) exists around the position of stable stacking fault energy (SFE), which allows cooperative movement of atoms within the slip plane. Alloying Mg with Y atoms increases the range of the PES, and ultimately promotes different sliding pathways in the Mg-Y alloy. These findings are consistent with experimentally observed activation of the pyramidal II <c + a> slip system in Mg-Y alloys, and provide important insight into the relationship between dislocation structure and macroscopic enhancement of plasticity.}, journal={ACTA MATERIALIA}, author={Ding, Zhigang and Liu, Wei and Sun, Hao and Li, Shuang and Zhang, Dalong and Zhao, Yonghao and Lavernia, Enrique J. and Zhu, Yuntian}, year={2018}, month={Mar}, pages={265–272} }
 @article{wang_huang_wang_li_zhu_2018, title={Quantifying the synergetic strengthening in gradient material}, volume={150}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2018.02.039}, abstractNote={Synergetic strengthening in heterostructures is a new strengthening mechanism for metals. Here, a simple procedure based on the relationship between hardness increment and yield strength increment of corresponding homogeneous counterparts is proposed to quantitatively predict the synergetic strengthening effect in gradient-structured Cu-30 wt%Zn. The synergetic strengthening among incompatible domains accounts for >33% of yield strength. The gradient structure with higher volume fraction of gradient domains exhibits higher synergetic strengthening. These results provide a new method for evaluating synergetic strengthening in heterostructured materials.}, journal={SCRIPTA MATERIALIA}, author={Wang, Y. F. and Huang, C. X. and Wang, M. S. and Li, Y. S. and Zhu, Y. T.}, year={2018}, month={Jun}, pages={22–25} }
 @misc{ovid'ko_valiev_zhu_2018, title={Review on superior strength and enhanced ductility of metallic nanomaterials}, volume={94}, ISSN={["1873-2208"]}, DOI={10.1016/j.pmatsci.2018.02.002}, abstractNote={Nanostructured metallic materials having nanocrystalline and ultrafine-grained structures show exceptional mechanical properties, e.g. superior strength, that are very attractive for various applications. However, superstrong metallic nanomaterials typically have low ductility at ambient temperatures, which significantly limits their applications. Nevertheless, several examples of nanostructured metals and alloys with concurrent high strength and good ductility have been reported. Such strong and ductile materials are ideal for a broad range of structural applications in transportation, medicine, energy, etc. Strong and ductile metallic nanomaterials are also important for functional applications where these properties are critical for the lifetime of nanomaterial-based devices. This article presents an overview of experimental data and theoretical concepts addressing the unique combination of superior strength and enhanced ductility of metallic nanomaterials. We consider the basic approaches and methods for simultaneously optimizing their strength and ductility, employing principal deformation mechanisms, crystallographic texture, chemical composition as well as second-phase nano-precipitates, carbon nanotubes and graphene. Examples of achieving such superior properties in industrial materials are reviewed and discussed.}, journal={PROGRESS IN MATERIALS SCIENCE}, author={Ovid'ko, I. A. and Valiev, R. Z. and Zhu, Y. T.}, year={2018}, month={May}, pages={462–540} }
 @misc{cao_ni_liao_song_zhu_2018, title={Structural evolutions of metallic materials processed by severe plastic deformation}, volume={133}, ISSN={["1879-212X"]}, url={https://doi.org/10.1016/j.mser.2018.06.001}, DOI={10.1016/j.mser.2018.06.001}, abstractNote={Bulk nanostructured (ns)/ultrafine-grained (UFG) metallic materials possess very high strength, making them attractive for high strength, lightweight and energy efficient applications. The most effective approach to produce bulk ns/UFG metallic materials is severe plastic deformation (SPD). In the last 30 years, significant research efforts have been made to explore SPD processing of materials, SPD-induced microstructural evolutions, and the resulting mechanical properties. There have been a few comprehensive reviews focusing mainly on SPD processing and the mechanical properties of the resulting materials. Yet no such a review on SPD-induced microstructural evolutions is available. This paper aims to provide a comprehensive review on important microstructural evolutions and major microstructural features induced by SPD processing in single-phase metallic materials with face-centered cubic structures, body-centered cubic structures, and hexagonal close-packed structures, as well as in multi-phase alloys. The corresponding deformation mechanisms and structural evolutions during SPD processing are discussed, including dislocation slip, deformation twinning, phase transformation, grain refinement, grain growth, and the evolution of dislocation density. A brief review on the mechanical properties of SPD-processed materials is also provided to correlate the structure with mechanical properties of SPD-processed materials, which is important for guiding structural design for optimum mechanical properties of materials.}, journal={MATERIALS SCIENCE & ENGINEERING R-REPORTS}, publisher={Elsevier BV}, author={Cao, Yang and Ni, Song and Liao, Xiaozhou and Song, Min and Zhu, Yuntian}, year={2018}, month={Nov}, pages={1–59} }
 @article{li_cao_gao_li_zhu_2018, title={Superior strength and ductility of 316L stainless steel with heterogeneous lamella structure}, volume={53}, ISSN={["1573-4803"]}, url={https://doi.org/10.1007/s10853-018-2322-4}, DOI={10.1007/s10853-018-2322-4}, number={14}, journal={JOURNAL OF MATERIALS SCIENCE}, publisher={Springer Science and Business Media LLC}, author={Li, Jiansheng and Cao, Yang and Gao, Bo and Li, Yusheng and Zhu, Yuntian}, year={2018}, month={Jul}, pages={10442–10456} }
 @article{xiao_cao_li_zhou_ma_mao_sha_wang_zhu_han_et al._2019, title={The formation mechanism of a novel interfacial phase with high thermal stability in a Mg-Gd-Y-Ag-Zr alloy}, volume={162}, ISSN={["1873-2453"]}, url={https://doi.org/10.1016/j.actamat.2018.10.005}, DOI={10.1016/j.actamat.2018.10.005}, abstractNote={Due to their unique precipitation behavior, magnesium-rare earth (Mg-RE) alloys exhibit excellent mechanical properties and decent thermal stability. In this work, a Mg-Gd-Y-Ag-Zr alloy was employed to investigate the segregation and interfacial phase formation at grain boundaries after plastic deformation and heat treatment. The interfacial phase was unequivocally investigated by aberration-corrected high-angle annular dark-filed scanning transmission electron microscopy (HAADF-STEM) from three different crystal directions and modeling, which reveals a hitherto unknown crystal structure (monoclinic: β = 139.1°, a = 1.20 nm, b = 1.04 nm and c = 1.59 nm). Its orientation relationship with the Mg matrix is: [101]//[112¯0]α, [302]//[101¯0]α and (010)//(0001)α. Different from the precipitates in matrix, the size of the interfacial phase was not sensitive to annealing temperature between 250 °C and 400 °C. Transformation of twin boundaries to coaxial grain boundaries via multiple twinning led to the generation of many high strain sites along the boundaries, which promoted the formation of the interfacial phase. The interfacial phase was stable up to 400 °C, which was about 100 °C higher than the dissolution temperature of β′ and γ" precipitates.}, journal={ACTA MATERIALIA}, publisher={Elsevier BV}, author={Xiao, L. R. and Cao, Y. and Li, S. and Zhou, H. and Ma, X. L. and Mao, L. and Sha, X. C. and Wang, Q. D. and Zhu, Y. T. and Han, X. D. and et al.}, year={2019}, month={Jan}, pages={214–225} }
 @article{liu_wang_cao_nie_zhou_yang_liu_an_liao_zhao_et al._2019, title={Unique defect evolution during the plastic deformation of a metal matrix composite}, volume={162}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2018.11.038}, abstractNote={During the plastic deformation of a metal matrix composite (MMC) containing non-deformable particles, high dislocation density and strong back stresses are expected because the particles help with blocking and accumulating dislocations. Here we report that the MMC has lower, instead of higher, dislocation density than the corresponding monolithic matrix material when they are deformed to high plastic strains, because smaller sub-grains in the MMC lowered dislocation generation rate and meanwhile promoted the dislocation interaction and annihilation in the matrix. This unique defect density evolution is a hitherto unknown but important factor affecting the mechanical properties of MMCs.}, journal={SCRIPTA MATERIALIA}, author={Liu, Yanfang and Wang, Fang and Cao, Yang and Nie, Jinfeng and Zhou, Hao and Yang, Huabing and Liu, Xiangfa and An, Xianghai and Liao, Xiaozhou and Zhao, Yonghao and et al.}, year={2019}, month={Mar}, pages={316–320} }
 @article{liang_liu_lin_wang_wang_zhao_zhu_2018, title={A multiscale architectured CuCrZr alloy with high strength, electrical conductivity and thermal stability}, volume={735}, ISSN={0925-8388}, url={http://dx.doi.org/10.1016/J.JALLCOM.2017.11.309}, DOI={10.1016/J.JALLCOM.2017.11.309}, abstractNote={A multiscale architectured structure, nanotwinned ultrafine grains surrounded by nano-precipitates at grain boundaries, was developed in a bulk Cu-Cr-Zr alloy prepared by aging treatment following equal-channel angular pressing. A superior combination of high strength, high electrical conductivity and good thermal stability was obtained, which avoided the trade-off among these important properties of electric conductive materials. This provides insight understanding on the mechanisms for strengthening, thermal stability and electrical conductivity, and could help the development of high-performance electrical conductors.}, journal={Journal of Alloys and Compounds}, publisher={Elsevier BV}, author={Liang, Ningning and Liu, Jizi and Lin, Sicong and Wang, Yue and Wang, Jing Tao and Zhao, Yonghao and Zhu, Yuntian}, year={2018}, month={Feb}, pages={1389–1394} }
 @article{ho_yildiz_bradford_zhu_fedkiw_2018, title={A silicon-impregnated carbon nanotube mat as a lithium-ion cell anode}, volume={48}, ISSN={["1572-8838"]}, DOI={10.1007/s10800-017-1140-8}, abstractNote={Silicon is a widely researched material for the anodes of lithium-ion batteries due to its high practical charge capacity of 3600 mAh g−1, which is ~ 10 times the specific capacity of conventional graphitic materials. However, silicon degrades rapidly in use due to its volumetric changes during charge/discharge of the battery, which makes it necessary to use complicated or costly methods to ameliorate capacity loss. Here, we report a novel silicon anode fabrication technique, which involves winding an aligned carbon nanotube (CNT) sheet and commensurately infiltrating it in situ with an aqueous solution containing silicon nanoparticles and hydroxypropyl guar binder. The resulting infiltrated felts were processed, evaluated, and compared to conventional silicon–carbon black anodes with the same carbon, silicon, and binder content as a proof of concept study. The felts had a large initial reversible capacity and promising rate capability. It is likely that the conductive CNT structure improved the charge transfer properties while lessening the effects of silicon volumetric expansion during lithiation. The results demonstrate that this novel anode fabrication method is viable and may be explored for further optimization. A novel fabrication method is described for the negative electrode for a lithium-ion battery: a CNT mat is formed by a drawing operation from a CNT vertical array while simultaneously being impregnated with a solution containing silicon nanoparticles and hydroxypropyl guar gum binder. The resulting CNT–Si anode structure shows improved lifetime cycling performance compared to traditional slurry-based silicon anodes.}, number={1}, journal={JOURNAL OF APPLIED ELECTROCHEMISTRY}, author={Ho, David N. and Yildiz, Ozkan and Bradford, Philip and Zhu, Yuntian and Fedkiw, Peter S.}, year={2018}, month={Jan}, pages={127–133} }
 @article{hu_jin_zhou_yin_yang_gong_zhu_sha_zhu_2017, title={Bauschinger effect and back stress in gradient Cu-Ge alloy}, volume={48A}, DOI={10.1007/s11661-017-4176-9}, number={9}, journal={Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science}, author={Hu, X. Z. and Jin, S. B. and Zhou, H. and Yin, Z. and Yang, J. and Gong, Y. L. and Zhu, Y.T. and Sha, G. and Zhu, X. K.}, year={2017}, pages={3943–3950} }
 @article{liang_zhao_wang_zhu_2017, title={Effect of grain structure on Charpy impact behavior of copper}, volume={7}, ISSN={["2045-2322"]}, DOI={10.1038/srep44783}, abstractNote={AbstractNanostructured (NS) and ultrafine-grained (UFG) materials have high strength and relatively low ductility. Their toughness has not been comprehensively investigated. Here we report the Charpy impact behavior and the corresponding microstructural evolutions in UFG Cu with equi-axed and elongated grains which were prepared by equal channel angular pressing (ECAP) for 2 and 16 passes at room temperature. It is found that their impact toughness (48 J/cm2) is almost comparable to that of coarse grained (CG) Cu: 55 J/cm2. The high strain rate during the Charpy impact was found to enhance the strain hardening capability of the UFG Cu due to the suppression of dynamic dislocation recovery. The crack in the CG Cu was blunted by dislocation-slip mediated plastic deformation, while the cracks in the UFG Cu were formed at grain boundaries and triple junctions due to their limited plasticity. Near the crack surfaces the elongated grains in ECAP-2 sample were refined by recrystallization, while equi-axed grains in the ECAP-16 sample grew larger.}, journal={SCIENTIFIC REPORTS}, author={Liang, Ningning and Zhao, Yonghao and Wang, Jingtao and Zhu, Yuntian}, year={2017}, month={Mar} }
 @article{liu_pan_zhao_topping_valiev_liao_lavernia_zhu_wei_2017, title={Effect of strain rate on the mechanical properties of a gum metal with various microstructures}, volume={132}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2017.04.052}, abstractNote={In this work, a bulk gum metal (GM) was fabricated via arc melting from high purity powders. The ingots were first extruded using a conventional route followed by equal channel angular pressing (ECAP). The mechanical behavior of the extruded GM and ECAP-processed GM was studied under both quasi-static and high strain rate compression conditions to evaluate the influence of strain rate. In addition, the associated mechanical anisotropy, or the lack thereof, was investigated through loading in different orientations with respect to the extrusion or ECAP direction. Precipitous stress drops were observed under dynamic compression of both extruded and ECAP-processed GM specimens when loading perpendicular to the extrusion direction. Adiabatic shear banding (ASB) was found to be associated with the precipitous stress drops on the dynamic stress-strain curves. The details of the ASBs were characterized by optical and scanning electron microscopy, with emphasis on electron backscattered diffraction (EBSD). The mechanisms responsible for the formation of ASB were examined both from thermal softening and geometrical softening perspectives. Significant microstructure refinement within ASBs was established, and a possible grain refinement mechanism was proposed.}, journal={ACTA MATERIALIA}, author={Liu, Silu and Pan, Z. L. and Zhao, Y. H. and Topping, T. and Valiev, R. Z. and Liao, X. Z. and Lavernia, E. J. and Zhu, Y. T. and Wei, Q.}, year={2017}, month={Jun}, pages={193–208} }
 @article{bian_yuan_zhu_wu_2017, title={Gradient structure produces superior dynamic shear properties}, volume={5}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2017.1334715}, abstractNote={ABSTRACT We report that gradient-structured twinning-induced plasticity steels have much superior dynamic shear properties over homogeneous nanostructured (NS) counterparts. The gradient structure was found to delay the nucleation of adiabatic shear bands (ASBs) at the NS surface layers and to reduce the propagation speed of ASB by an order of magnitude as compared with homogeneous NS materials. The conventional maximum stress criterion on ASB initiation for homogeneous materials is found not valid for gradient structure. These findings may provide insights for designing impact-tolerant gradient structures with excellent dynamic properties. GRAPHICAL ABSTRACT IMPACT STATEMENT Gradient structures were found to produce superior dynamic shear properties that are not accessible to their homogeneous counterparts due to the suppression of nucleation and propagation of adiabatic shear bands.}, number={7}, journal={MATERIALS RESEARCH LETTERS}, author={Bian, Xiangde and Yuan, Fuping and Zhu, Yuntian and Wu, Xiaolei}, year={2017}, pages={501–507} }
 @article{wu_zhu_2017, title={Heterogeneous materials: a new class of materials with unprecedented mechanical properties}, volume={5}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2017.1343208}, DOI={10.1080/21663831.2017.1343208}, abstractNote={ABSTRACT Here we present a perspective on heterogeneous materials, a new class of materials possessing superior combinations of strength and ductility that are not accessible to their homogeneous counterparts. Heterogeneous materials consist of domains with dramatic strength differences. The domain sizes may vary in the range of micrometers to millimeters. Large strain gradients near domain interfaces are produced during deformation, which produces a significant back-stress to strengthen the material and to produce high back-stress work hardening for good ductility. High interface density is required to maximize the back-stress, which is a new strengthening mechanism for improving mechanical properties. GRAPHICAL ABSTRACT IMPACT STATEMENT Heterogeneous materials are becoming the next hot research field after the nanomaterials era.}, number={8}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Wu, Xiaolei and Zhu, Yuntian}, year={2017}, month={Jun}, pages={527–532} }
 @article{yu_zhang_yildiz_deng_zhao_bradford_li_zhu_2017, title={Investigation of microcombing parameters in enhancing the properties of carbon nanotube yarns}, volume={134}, ISSN={["1873-4197"]}, DOI={10.1016/j.matdes.2017.08.035}, abstractNote={Microcombing has been reported as a novel processing approach for reducing waviness and improving alignment of carbon nanotubes (CNTs), which effectively enhances the performance of materials made from CNT sheets. In this study, we have systematically investigated the effects of microcombing parameters on the properties of CNT yarns. It is found that the electrical and mechanical properties of CNT yarns first improved with increasing degree of microcombing and then degraded with over-combing. At the optimum degree of microcombing, the electrical conductivity, tensile strength, and Young's modulus of the CNT yarns were improved to 140%, 140%, and 230%, respectively, over those of uncombed yarns. The enhanced yarn properties were resulted from reduced nanotube waviness, improved CNT alignment and denser packing structure, which led to a more uniform yarn structure. On the other hand, over-combing degraded structural uniformity, resulting in lower electrical and mechanical properties. These observations are expected to help with future selection of microcombing parameters for producing high-quality CNT yarns and polymer-CNT composite yarns for superior electrical and mechanical properties.}, journal={MATERIALS & DESIGN}, author={Yu, Yingying and Zhang, Liwen and Yildiz, Ozkan and Deng, Haotian and Zhao, Changhao and Bradford, Philip D. and Li, Jianying and Zhu, Yuntian}, year={2017}, month={Nov}, pages={181–187} }
 @article{zhao_zhu_2017, title={Lattice expansion and grain boundary excess volume of nanocrystalline se prepared by mechanical milling}, volume={48}, number={1}, journal={Reviews on Advanced Materials Science}, author={Zhao, Y. H. and Zhu, Y. T.}, year={2017}, pages={52–61} }
 @article{goken_eggeler_zhu_lu_2017, title={Mechanical properties and microstructure of advanced metallic alloys in honor of Prof. Hael Mughrabi - Part A fracture and fatigue introduction}, volume={32}, number={23}, journal={Journal of Materials Research}, author={Goken, M. and Eggeler, G. and Zhu, Y. T. and Lu, L.}, year={2017}, pages={4273–4275} }
 @article{goken_eggeler_zhu_lu_2017, title={Mechanical properties and microstructure of advanced metallic alloys in honor of Prof. Hael Mughrabi - Part B - high temperature and nanomaterials introduction}, volume={32}, number={24}, journal={Journal of Materials Research}, author={Goken, M. and Eggeler, G. and Zhu, Y. T. and Lu, L.}, year={2017}, pages={4463–4465} }
 @misc{li_li_nie_cao_zhao_zhu_2017, title={Microstructural evolution and mechanical properties of a 5052 Al alloy with gradient structures}, volume={32}, number={23}, journal={Journal of Materials Research}, author={Li, Y. S. and Li, L. Z. and Nie, J. F. and Cao, Y. and Zhao, Y. H. and Zhu, Y. T.}, year={2017}, pages={4443–4451} }
 @article{tang_zhao_islamgaliev_valiev_zhu_2017, title={Microstructure Microstructure and thermal stability of nanocrystalline Mg-Gd-Y-Zr alloy processed by high pressure torsion}, volume={721}, ISSN={["1873-4669"]}, url={https://doi.org/10.1016/j.jallcom.2017.05.164}, DOI={10.1016/j.jallcom.2017.05.164}, abstractNote={Fabricating bulk coarse-grain Mg alloys into nanocrystallines (NCs) via severe plastic deformation along with remaining the thermal stability of nanostructures has been a challenging issue. Here we employed high-pressure torsion at room temperature to prepare nanocrystalline (NC) Mg-Gd-Y-Zr alloy with an average grain size of 80 nm. The appearance of NC structures was associated with stacking fault formation, due to the lowering of stacking fault energy by Gd and Y according to the density-functional theory (DFT) calculations. The NC Mg-Gd-Y-Zr alloy showed high thermal stability up to 250 °C, which is comparable with that of its coarse-grained and fine-grained counterpart. This high thermal stability against nanograin growth was caused by stable precipitation at grain boundaries. Therefore, alloying Mg with Gd and Y not only helped with formation of NCs, but also improved the thermal stability.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, publisher={Elsevier BV}, author={Tang, Lingling and Zhao, Yonghao and Islamgaliev, R. K. and Valiev, R. Z. and Zhu, Y. T.}, year={2017}, month={Oct}, pages={577–585} }
 @article{nie_wang_li_cao_liu_zhao_zhu_2017, title={Microstructure evolution and mechanical properties of Al-TiB2/TiC in situ aluminum-based composites during Accumulative Roll Bonding (ARB) process}, volume={10}, number={2}, journal={Materials}, author={Nie, J. F. and Wang, F. and Li, Y. S. and Cao, Y. and Liu, X. F. and Zhao, Y. H. and Zhu, Y. T.}, year={2017} }
 @article{xu_zhang_cheng_mathaudhu_scattergood_koch_lavernia_zhu_2017, title={On the origin and behavior of irradiation-induced c-component dislocation loops in magnesium}, volume={131}, ISSN={["1873-2453"]}, url={https://doi.org/10.1016/j.actamat.2017.04.015}, DOI={10.1016/j.actamat.2017.04.015}, abstractNote={C-component dislocation loops are one of the unique defects in hexagonal close-packed (hcp) crystals that promote the accelerated growth and void formation under irradiation. Here, we report in situ observation of c-component dislocation loop formation in Mg under electron irradiation with emphasis on their atomic structures. Aberration-corrected scanning transmission electron microscopy imaging is utilized to reveal four possible types of double-layer loops, which were identified as different types of stacking fault and dislocation core structures. Triple- and quadruple-layer c-component dislocation loops were also observed. The formation mechanisms of the four types of double-layer loops were revealed via molecular dynamics simulations. The experimentally observed formation rate of the single- and double-layer dislocation loops is controlled by their formation energies. Our direct experimental observations in combination with molecular dynamics simulations provide fundamental insight into the mechanisms governing nucleation and growth of the c-component dislocation loops as well as their interactions, which could potentially help with future development of irradiation-resistant materials.}, journal={ACTA MATERIALIA}, publisher={Elsevier BV}, author={Xu, Weizong and Zhang, Yongfeng and Cheng, Guangming and Mathaudhu, Suveen N. and Scattergood, Ronald O. and Koch, Carl C. and Lavernia, Enrique J. and Zhu, Yuntian}, year={2017}, month={Jun}, pages={457–466} }
 @article{zou_zhang_xu_zhao_zhu_li_2017, title={Soldering carbon nanotube fibers by targeted electrothermal-induced carbon deposition}, volume={121}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2017.05.091}, abstractNote={We introduce a facile approach to solder carbon nanotube (CNT) fibers by depositing carbon nanostructures at targeted fiber connections. Electrothermal induced deposition (ETID) process facilitates thermal chemical vapor deposition via current-induced Joule heating. Various carbon structures are formed between the overlapped fibers, with nanofibers covered by amorphous carbon and carbon nanowalls, resulting in effective soldering. The soldered connection between crossing fibers can be much stronger than the pristine CNT fiber: the separation force of the connection is measured to be up to 460 mN while the fracture force of the fiber is about 74 mN. The contact resistance decreased from >120 to 4.8 Ω after the ETID treatment. Such robust electrical soldering can be applied to connect CNT fibers in both parallel and cross configuration, to generate a soldered one-dimensional (1D) line, 2D network, and 3D cage.}, journal={CARBON}, author={Zou, Jingyun and Zhang, Xiaohua and Xu, Chao and Zhao, Jingna and Zhu, Yuntian T. and Li, Qingwen}, year={2017}, month={Sep}, pages={242–247} }
 @article{bian_yuan_wu_zhu_2017, title={The Evolution of Strain Gradient and Anisotropy in Gradient-Structured Metal}, volume={48A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-017-4199-2}, abstractNote={Gradient-structured metals have been reported to possess superior mechanical properties, which were attributed to their mechanical heterogeneity. Here we report in-situ observation of the evolution of strain gradient and anisotropy during tensile testing of a gradient-structured metal. Strain gradients and anisotropy in the lateral directions were observed to increase with increasing applied tensile strain. In addition, the equivalent Poisson's ratio showed gradient, which evolved with applied strain. The gradient structure produced higher deformation anisotropy than coarse-grained homogeneous structure, and the anisotropy increased with increasing tensile strain. The strain gradient and anisotropy resulted in strong back-stress hardening, large strain gradients, and a high density of geometrically necessary dislocations, which helped with increasing the ductility.}, number={9}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Bian, Xiangde and Yuan, Fuping and Wu, Xiaolei and Zhu, Yuntian}, year={2017}, month={Sep}, pages={3951–3960} }
 @article{tang_liu_ding_zhang_zhao_lavernia_zhu_2016, title={Alloying Mg with Gd and Y: Increasing both plasticity and strength}, volume={115}, ISSN={["1879-0801"]}, DOI={10.1016/j.commatsci.2016.01.003}, abstractNote={The addition of rare elements to Mg enhances mechanical behavior via solution and precipitation strengthening mechanisms. To provide fundamental insight into the underlying mechanisms, we apply density-functional theory (DFT) calculations to systematically study the generalized planar fault energy (GPFE) for pure Mg and its alloys with Gd, Y, and Gd–Y. Special attention is focused on the {0 0 0 1}〈1 1¯ 0 0〉 basal and {1 1¯ 0 0}〈1 1 2¯ 0〉 prismatic slip systems. Our results show that the addition of Gd and Y in Mg significantly reduces the magnitude of GPFE, in particular for the {1 1¯ 0 0}〈1 1 2¯ 0〉 prismatic slip system. The analysis of the charge density distribution reveals that the predicted reduction in GPFE can be primarily attributed to a decrease of shear resistance between the slip planes. Based on the criterion for the anisotropy of the dislocation mobility and disembrittlement parameter, we demonstrate that alloying Mg with Gd and Y yields lower resistance to slip and hence an improvement in plasticity. Our results also suggest that the strength and plasticity of the Mg–Gd–Y system can be simultaneously enhanced due to charge transfer between Mg and alloying atoms.}, journal={COMPUTATIONAL MATERIALS SCIENCE}, author={Tang, Lingling and Liu, Wei and Ding, Zhigang and Zhang, Dalong and Zhao, Yonghao and Lavernia, Enrique J. and Zhu, Yuntian}, year={2016}, month={Apr}, pages={85–91} }
 @article{yuan_tsai_sha_liu_horita_zhu_wang_2016, title={Atomic-scale homogenization in an fcc-based high-entropy alloy via severe plastic deformation}, volume={686}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2016.05.337}, abstractNote={The atomic-scale homogenization of a face-centered-cubic-based high-entropy alloy (HEA), Al0.3Cu0.5CoCrFeNi, using severe plastic deformation (SPD) is reported. Atom probe tomography revealed that water quenching from high temperature cannot produce a homogeneous single phase, and clustering of Cu, Al and Ni still exists. Subsequent processing by high-pressure torsion produced nanostructured non-equilibrium single phase with homogeneous elemental distribution at atomic scale. Importantly, such a non-equilibrium single phase is stable at room temperature due to the sluggish diffusion kinetics. These observations suggest that SPD is an effective approach for producing single-phase HEAs for fundamental studies and applications.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Yuan, Hao and Tsai, Ming-Hung and Sha, Gang and Liu, Fan and Horita, Zenji and Zhu, Yuntian and Wang, Jing Tao}, year={2016}, month={Nov}, pages={15–23} }
 @article{yang_pan_yuan_zhu_wu_2016, title={Back stress strengthening and strain hardening in gradient structure}, volume={4}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2016.1153004}, abstractNote={We report significant back stress strengthening and strain hardening in gradient structured (GS) interstitial-free (IF) steel. Back stress is long-range stress caused by the pileup of geometrically necessary dislocations (GNDs). A simple equation and a procedure are developed to calculate back stress basing on its formation physics from the tensile unloading–reloading hysteresis loop. The gradient structure has mechanical incompatibility due to its grain size gradient. This induces strain gradient, which needs to be accommodated by GNDs. Back stress not only raises the yield strength but also significantly enhances strain hardening to increase the ductility. Impact Statement: Gradient structure leads to high back stress hardening to increase strength and ductility. A physically sound equation is derived to calculate the back stress from an unloading/reloading hysteresis loop. GRAPHICAL ABSTRACT}, number={3}, journal={MATERIALS RESEARCH LETTERS}, author={Yang, Muxin and Pan, Yue and Yuan, Fuping and Zhu, Yuntian and Wu, Xiaolei}, year={2016}, pages={145–151} }
 @article{wu_yang_yuan_chen_zhu_2016, title={Combining gradient structure and TRIP effect to produce austenite stainless steel with high strength and ductility}, volume={112}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2016.04.045}, abstractNote={We report a design strategy to combine the benefits from both gradient structure and transformation-induced plasticity (TRIP). The resultant TRIP-gradient steel takes advantage of both mechanisms, allowing strain hardening to last to a larger plastic strain. 304 stainless steel sheets were treated by surface mechanical attrition to synthesize gradient structure with a central coarse-grained layer sandwiched between two grain-size gradient layers. The gradient layer is composed of submicron-sized parallelepiped austenite domains separated by intersecting ε-martensite plates, with increasing domain size along the depth. Significant microhardness heterogeneity exists not only macroscopically between the soft coarse-grained core and the hard gradient layers, but also microscopically between the austenite domain and ε-martensite walls. During tensile testing, the gradient structure causes strain partitioning, which evolves with applied strain, and lasts to large strains. The γ → α′ martensitic transformation is triggered successively with an increase of the applied strain and flow stress. Importantly, the gradient structure prolongs the TRIP effect to large plastic strains. As a result, the gradient structure in the 304 stainless steel provides a new route towards a good combination of high strength and ductility, via the co-operation of both the dynamic strain partitioning and TRIP effect.}, journal={ACTA MATERIALIA}, author={Wu, X. L. and Yang, M. X. and Yuan, F. P. and Chen, L. and Zhu, Y. T.}, year={2016}, month={Jun}, pages={337–346} }
 @article{ding_liu_li_zhang_zhao_lavernia_zhu_2016, title={Contribution of van der Waals forces to the plasticity of magnesium}, volume={107}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2016.01.026}, abstractNote={The accurate determination of stacking fault energies (SFE) and associated restoring forces is important for understanding plastic deformation, especially the dislocation emission and motion in metals. In this work, we use density-functional theory (DFT) calculations to, systematically study the all-dimension relaxed atomic models of Mg crystal slip, with a special focus on the “subslip modes” in prismatic and pyramidal slip systems. We find that slip systems with large interplanar distances are readily activated, which agrees well with experimental observations. Inclusion of the ubiquitous van der Waals (vdW) interactions results in lower generalized stacking fault energy curves. Remarkably, the unstable SFE value of pyramidal-II system is strongly reduced by up to 69 mJ/m2, and the related restoring stress is lowered by 0.74 GPa after taking into account the vdW energy. Our calculations indicate significant effect of vdW forces on the plasticity of Mg.}, journal={ACTA MATERIALIA}, author={Ding, Zhigang and Liu, Wei and Li, Shuang and Zhang, Dalong and Zhao, Yonghao and Lavernia, Enrique J. and Zhu, Yuntian}, year={2016}, month={Apr}, pages={127–132} }
 @article{liu_ma_li_zhang_trimby_liao_li_zhao_zhu_2016, title={Effect of triple junctions on deformation twinning in a nanostructured Cu-Zn alloy: A statistical study using transmission Kikuchi diffraction}, volume={7}, journal={Beilstein Journal of Nanotechnology}, author={Liu, S. L. and Ma, X. L. and Li, L. Z. and Zhang, L. W. and Trimby, P. W. and Liao, X. Z. and Li, Y. S. and Zhao, Y. H. and Zhu, Y. T.}, year={2016}, pages={1501–1506} }
 @article{tang_zhao_islamgaliev_tsao_valiev_lavernia_zhu_2016, title={Enhanced strength and ductility of AZ80 Mg alloys by spray forming and ECAP}, volume={670}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2016.06.031}, abstractNote={The relatively low strength and poor ductility of conventional AZ80 Mg alloys have been attributed to the limited number of independent slip systems, in combination with the formation of fragile eutectic β-Mg17Al12 networks at grain boundaries. In an effort to overcome these limitations, spray forming followed by equal channel angular pressing (ECAP) was employed to obtain a unique bi-modal microstructure: coarse grains were separated and surrounded by deformation networks consisting of ultrafine-grained Mg with an average grain size of 0.6 µm and ellipsoidal shaped β-Mg17Al12 particles with sizes of 200–300 nm. Tensile tests revealed the advantage of this structure: a yield strength of 235 MPa combined with an elongation to failure of 14%; the values are significantly higher than those of their conventional counterparts (100 MPa-12%, and 140 MPa-5%). The underlying strengthening and deformation mechanisms of this particular microstructure are discussed and analyzed.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Tang, Lingling and Zhao, Yonghao and Islamgaliev, R. K. and Tsao, Chi Y. A. and Valiev, R. Z. and Lavernia, E. J. and Zhu, Y. T.}, year={2016}, month={Jul}, pages={280–291} }
 @article{nie_liu_wang_zhao_li_cao_zhu_2016, title={Fabrication of Al/Mg/Al composites via accumulative roll bonding and their mechanical properties}, volume={9}, number={11}, journal={Materials}, author={Nie, J. F. and Liu, M. X. and Wang, F. and Zhao, Y. H. and Li, Y. S. and Cao, Y. and Zhu, Y. T.}, year={2016} }
 @article{wang_li_zhang_zhao_zhu_2017, title={Gradient Structured Copper by Rotationally Accelerated Shot Peening}, volume={33}, ISSN={["1005-0302"]}, DOI={10.1016/j.jmst.2016.11.006}, abstractNote={A new technology—rotationally accelerated shot peening (RASP), was developed to prepare gradient structured materials. By using centrifugal acceleration principle and large steel balls, the RASP technology can produce much higher impact energy compared to conventional shot peening. As a proof-of-concept demonstration, the RASP was utilized to refine the surface layer in pure copper (Cu) with an average grain size of ~85 nm. The grain size increases largely from surface downwards the bulk, forming an 800 μm thick gradient-structured surface layer and consequently a micro-hardness gradient. The difference between the RASP technology and other established techniques in preparing gradient structured materials is discussed. The RASP technology exhibits a promoting future for large-scale manufacturing of gradient materials.}, number={7}, journal={JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY}, author={Wang, X. and Li, Y. S. and Zhang, Q. and Zhao, Y. H. and Zhu, Y. T.}, year={2017}, month={Jul}, pages={758–761} }
 @article{cheng_xu_wang_misra_zhu_2016, title={Grain size effect on radiation tolerance of nanocrystalline Mo}, volume={123}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2016.06.007}, abstractNote={We report a significant grain size effect on radiation tolerance of nanocrystalline Mo under He ion irradiation. Irradiation-induced dislocation loops mainly contribute to the irradiation-induced hardening of Mo films with grain size of > 90 nm, while few such loops in those with grain size of < 90 nm. The hardness increment after irradiation decreases with decreasing the grain size, and approaches zero at the grain size of 25 nm. Also, the size and the density of irradiation-induced He bubbles decrease as the grain size decreases. This observation provides direct evidence that nanocrystalline body-centered-cubic metals have greater radiation tolerance than their ultra-fine-grained or coarse-grained counterparts.}, journal={SCRIPTA MATERIALIA}, author={Cheng, G. M. and Xu, W. Z. and Wang, Y. Q. and Misra, A. and Zhu, Y. T.}, year={2016}, month={Oct}, pages={90–94} }
 @article{huang_li_zhu_fedkiw_2017, title={Investigation and modification of carbon buckypaper as an electrocatalyst support for oxygen reduction}, volume={47}, ISSN={["1572-8838"]}, DOI={10.1007/s10800-016-1023-4}, number={1}, journal={JOURNAL OF APPLIED ELECTROCHEMISTRY}, author={Huang, Sheng-Yang and Li, Qingwen and Zhu, Yuntian and Fedkiw, Peter S.}, year={2017}, month={Jan}, pages={105–115} }
 @article{tang_zhao_liang_islamgaliev_valiev_zhu_2016, title={Localized deformation via multiple twinning in a Mg-Gd-Y-Zr alloy processed by high-pressure torsion}, volume={677}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2016.09.005}, abstractNote={Different with common grain refinement dominated by dislocation activities, grain subdivision induced by sequential activation of multiple twinning was observed in a Mg-Gd-Y-Zr magnesium alloy via high-pressure torsion. Deformation bands were evolved from large primary twin bands, which contained refined grains through localized multiple twinning. Nanometer-scaled amorphous bands were also observed within deformation bands in Mg alloys for the first time. These observations indicate that localized deformation via multiple twinning and the consequent formation of deformation bands are potential routes to grain refinement in rare earth-magnesium alloys.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Tang, Lingling and Zhao, Yonghao and Liang, Ningning and Islamgaliev, R. K. and Valiev, R. Z. and Zhu, Y. T.}, year={2016}, month={Nov}, pages={68–75} }
 @article{ma_huang_moering_ruppert_hoeppel_goeken_narayan_zhu_2016, title={Mechanical properties of copper/bronze laminates: Role of interfaces}, volume={116}, ISSN={["1873-2453"]}, url={https://doi.org/10.1016/j.actamat.2016.06.023}, DOI={10.1016/j.actamat.2016.06.023}, abstractNote={Interfaces play a crucial role in mechanical behaviors of both laminated and gradient structured materials. In this work, copper/bronze laminates with varying interface spacing were fabricated by accumulative roll bonding and subsequent annealing to systematically study the interface effect on mechanical properties. Heterogeneities exist in chemical composition, grain size, hardness and texture across the interfaces. Simultaneous improvement of strength and ductility with decreasing interface spacing is found in tensile tests. Extra geometrically necessary dislocations (GNDs) are found to accumulate in the vicinity of interfaces, which is due to mechanical incompatibility across the interfaces. Importantly, an interface-affected zone spanning a few micrometers was found, which is not affected by interface spacing. These observations suggest the existence of an optimum spacing, which may produce the highest hardening capacity and ductility without sacrificing strength.}, journal={ACTA MATERIALIA}, publisher={Elsevier BV}, author={Ma, Xiaolong and Huang, Chongxiang and Moering, Jordan and Ruppert, Mathis and Hoeppel, Heinz Werner and Goeken, Mathias and Narayan, Jagdish and Zhu, Yuntian}, year={2016}, month={Sep}, pages={43–52} }
 @article{an_lin_sha_huang_ringer_zhu_liao_2016, title={Microstructural evolution and phase transformation in twinning induced plasticity steel induced by high-pressure torsion}, volume={109}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2016.02.045}, abstractNote={The microstructural evolution of twinning-induced plasticity steel during high-pressure torsion (HPT) processing at 573 K was systematically evaluated. Due to the high processing temperature, the formation of a homogeneous nanostructure was primarily dominated by complicated dislocation and grain boundary activities in lieu of deformation twinning. Apart from the grain refinement process, phase transformation took place at late stages of deformation, resulting in the microstructural fingerprint of equaxied nanograins with multiple phases in the steel. On account of remarkable elemental redistribution, the diffusion-controlled nature of the transformation was convincingly identified. During the transformation, although the cementite also initially formed, austenite eventually decomposed into ferrite and Mn-riched M23C6 carbide, implying that Mn is the pivotal alloying element for the transformation kinetics. Owing to the sluggish bulk diffusivity of Mn, it is proposed that a high density of defects, nanostructures and the HPT processing play a crucial role in promoting the elemental diffusion and segregation and in stimulating the phase transformation.}, journal={ACTA MATERIALIA}, author={An, X. H. and Lin, Q. Y. and Sha, G. and Huang, M. X. and Ringer, S. P. and Zhu, Y. T. and Liao, X. Z.}, year={2016}, month={May}, pages={300–313} }
 @article{dai_zhu_huang_2016, title={Microstructure and tensile behaviour of pure titanium produced after high-energy shot peening}, volume={32}, ISSN={["1743-2847"]}, DOI={10.1080/02670836.2015.1121598}, abstractNote={ In this study, the microstructure and tensile behaviour of pure titanium processed by means of high-energy shot peening have been studied. The results show that a nanocrystalline surface layer is prepared on the surface of pure titanium. During severe deformation, the dislocations, twins and slip bands with single orientation are formed first, then the intersections of twins and slip bands are observed, and then the subgrains appear near or in the slip bands and finally the randomly oriented nano-grains are formed due to the further breakdown. After high-energy shot peening, the ultimate tensile strength and the yield strength increase by 27 and 40%, while the elongation decreases by 64% after treatment, due to the increasing dislocation density, micro-strain and the grain refinement. }, number={13}, journal={MATERIALS SCIENCE AND TECHNOLOGY}, author={Dai, S. and Zhu, Y. and Huang, Z.}, year={2016}, pages={1323–1329} }
 @article{dai_zhu_huang_2016, title={Microstructure evolution and strengthening mechanisms of pure titanium with nano-structured surface obtained by high energy shot peening}, volume={125}, ISSN={["0042-207X"]}, DOI={10.1016/j.vacuum.2016.01.001}, abstractNote={In this study, the microstructure evolution and strengthening mechanisms of pure titanium processed by high energy shot peening (HESP) have been studied. The results show that the deformation layer is formed on the surface and the microstructure exhibits with the equiaxed 20–40 μm grains in the matrix after HESP. A nanocrystal surface layer is produced by means of HESP on pure titanium. The formation of nano-grains on the surface can be separated into four steps: (1) the formation of the dislocations tangles; (2) the occurrence of the intersection of twins; (3) the appearance of slip band and subgrains; (4) the formation of uniformly distributed nanometer-scale grains. With increasing the holding time, the strength increases and the elongation decreases due to the work hardening effect and the formation of the nanocrystals on the surface.}, journal={VACUUM}, author={Dai, Shijuan and Zhu, Yuntian and Huang, Zhaowen}, year={2016}, month={Mar}, pages={215–221} }
 @article{fang_ma_zhang_zhu_2016, title={Nucleation of deformation twins in nanocrystalline fcc alloys}, volume={96}, ISSN={["1478-6443"]}, DOI={10.1080/14786435.2016.1240379}, abstractNote={Abstract An earlier dislocation model for predicting the grain size effect on deformation twinning in nanocrystalline (nc) face-centred-cubic (fcc) metals has been found valid for pure metals but problematic for alloys. The problem arises from the assumption that the stacking-fault energy (γSF) is twice the coherent twin-boundary energy (γfcc), which is approximately correct for pure fcc metals, but not for alloys. Here we developed a modified dislocation model to explain the deformation twinning nucleation in fcc alloy systems, where γSF ≠ 2γtwin. This model can explain the differences in the formations of deformation twins in pure metals and alloys, which is significant in low stacking-fault energy alloys. We also describe the procedure to calculate the optimum grain size for twinning in alloy systems and present a method to estimate γtwin.}, number={36}, journal={PHILOSOPHICAL MAGAZINE}, author={Fang, Xiaotian and Ma, Xiaolong and Zhang, Liwen and Zhu, Yuntian}, year={2016}, pages={3790–3802} }
 @article{valiev_estrin_horita_langdon_zehetbauer_zhu_2016, title={Producing Bulk Ultrafine-Grained Materials by Severe Plastic Deformation: Ten Years Later}, volume={68}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-016-1820-6}, abstractNote={It is now well established that the processing of bulk solids through the application of severe plastic deformation (SPD) leads to exceptional grain refinement to the submicrometer or nanometer level. Extensive research over the last decade has demonstrated that SPD processing also produces unusual phase transformations and leads to the introduction of a range of nanostructural features, including nonequilibrium grain boundaries, deformation twins, dislocation substructures, vacancy agglomerates, and solute segregation and clustering. These many structural changes provide new opportunities for fine tuning the characteristics of SPD metals to attain major improvements in their physical, mechanical, chemical, and functional properties. This review provides a summary of some of these recent developments. Special emphasis is placed on the use of SPD processing in achieving increased electrical conductivity, superconductivity, and thermoelectricity, an improved hydrogen storage capability, materials for use in biomedical applications, and the fabrication of high-strength metal-matrix nanocomposites.}, number={4}, journal={JOM}, author={Valiev, Ruslan Z. and Estrin, Yuri and Horita, Zenji and Langdon, Terence G. and Zehetbauer, Michael J. and Zhu, Yuntian}, year={2016}, month={Apr}, pages={1216–1226} }
 @article{faraji_yildiz_rost_stano_farahbakhsh_zhu_bradford_2017, title={Radial growth of multi-walled carbon nanotubes in aligned sheets through cyclic carbon deposition and graphitization}, volume={111}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2016.10.012}, abstractNote={Carbon coated aligned multi-walled carbon nanotube (AMWCNT/C) sheets were used for studying the controlled radial growth of MWCNTs. Pyrolytic carbon (PyC) was deposited on the surface of nanotubes using multiple cycles of chemical vapor infiltration. Morphological and structural characterization showed that when graphitization was done in one step, after the deposition of multiple cycles of PyC, the presence of a large amount of disordered carbon on the surface of nanotubes led to a poorly graphitized coating structure that did not resembled nanotube walls anymore. Graphitization of the AMWCNT/C sheets after each deposition cycle prevented the development of disordered carbon during the subsequent PyC deposition cycles. Using the cyclic-graphitization method, thick PyC coating layers were successfully graphitized into a crystalline structure that could not be differentiated from the original nanotube walls. TEM observation and X-ray data confirmed radial growth of nanotubes, while spectra collected from Raman spectroscopy revealed that radially grown CNTs had the same quality as graphitized pristine nanotubes. The focus of this study was to compare the effect of cyclic graphitization with a one-step graphitization method to gain insight on the necessary parameters needed to radially grow high quality CNTs.}, journal={CARBON}, author={Faraji, Shaghayegh and Yildiz, Ozkan and Rost, Christina and Stano, Kelly and Farahbakhsh, Nasim and Zhu, Yuntian and Bradford, Philip D.}, year={2017}, month={Jan}, pages={411–418} }
 @article{qiu_wang_su_tang_zheng_zhu_wang_norris_bradford_zhu_et al._2016, title={Remarkably enhanced thermal transport based on a flexible horizontally-aligned carbon nanotube array film}, volume={6}, ISSN={["2045-2322"]}, DOI={10.1038/srep21014}, abstractNote={AbstractIt has been more than a decade since the thermal conductivity of vertically aligned carbon nanotube (VACNT) arrays was reported possible to exceed that of the best thermal greases or phase change materials by an order of magnitude. Despite tremendous prospects as a thermal interface material (TIM), results were discouraging for practical applications. The primary reason is the large thermal contact resistance between the CNT tips and the heat sink. Here we report a simultaneous sevenfold increase in in-plane thermal conductivity and a fourfold reduction in the thermal contact resistance at the flexible CNT-SiO2 coated heat sink interface by coupling the CNTs with orderly physical overlapping along the horizontal direction through an engineering approach (shear pressing). The removal of empty space rapidly increases the density of transport channels and the replacement of the fine CNT tips with their cylindrical surface insures intimate contact at CNT-SiO2 interface. Our results suggest horizontally aligned CNT arrays exhibit remarkably enhanced in-plane thermal conductivity and reduced out-of-plane thermal conductivity and thermal contact resistance. This novel structure makes CNT film promising for applications in chip-level heat dissipation. Besides TIM, it also provides for a solution to anisotropic heat spreader which is significant for eliminating hot spots.}, journal={SCIENTIFIC REPORTS}, author={Qiu, L. and Wang, X. T. and Su, G. P. and Tang, D. W. and Zheng, X. H. and Zhu, J. and Wang, Z. G. and Norris, P. M. and Bradford, P. D. and Zhu, Y. T. and et al.}, year={2016}, month={Feb} }
 @article{yin_yang_ma_moering_yang_gong_zhu_zhu_2016, title={Strength and ductility of gradient structured copper obtained by surface mechanical attrition treatment}, volume={105}, ISSN={["1873-4197"]}, DOI={10.1016/j.matdes.2016.05.015}, abstractNote={By using surface mechanical attrition treatment (SMAT) at room temperature, a gradient structure (GS) is generated in the surface layer of bulk pure copper samples, which exhibits good uniform elongation and high yield strength simultaneously. Changing SMAT processing time leads to different gradient structures with various component fractions and therefore tune their mechanical properties. The yield strength of the SMAT samples is much higher than the sum of standalone GS layer and coarse-grained (CG) matrix, indicating a synergetic strengthening. Repeated stress relaxation tests were performed to characterize the evolution of mobile dislocations. It was found that the relative mobile dislocation density of SMAT processed sample first drops and then increases with increasing tensile strain. The evolution of mobile dislocations correlates well with strain-hardening evolution. These observations provide insight for the superior combination of high strength and good ductility in SMAT samples.}, journal={MATERIALS & DESIGN}, author={Yin, Zhe and Yang, Xincheng and Ma, Xiaolong and Moering, Jordan and Yang, Jian and Gong, Yulan and Zhu, Yuntian and Zhu, Xinkun}, year={2016}, month={Sep}, pages={89–95} }
 @article{zou_zhang_zhao_lei_zhao_zhu_li_2016, title={Strengthening and toughening effects by strapping carbon nanotube cross-links with polymer molecules}, volume={135}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2016.09.019}, abstractNote={Cross-linked carbon nanotube (CNT) networks provide efficient load and charge transfer within their assemblies. Injection chemical vapor deposition (iCVD) has been widely used to obtain such structure with rich cross-links. However, in the iCVD process, a certain organic by-products, probably dioctyl phthalate (DOP) molecules, co-exist in the CNT network, which degrade the interfacial property between CNTs. The removal of the DOP-like molecules can remarkably strengthen the CNT cross-links, improving the assembly's modulus, but it also causes significant loss in toughness. Here we report that strapping up the strengthened cross-links with long-chain and inherently polar polymer polyvinylidene fluoride (PVDF) can result in a simultaneous strengthening and toughening of CNT assemblies, e.g. CNT fibers. This finding represents a new strategy to develop advanced CNT-based macroscopic assembly materials.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Zou, Jingyun and Zhang, Xiaohua and Zhao, Jingna and Lei, Chaoshuai and Zhao, Yonghao and Zhu, Yuntian and Li, Qingwen}, year={2016}, month={Oct}, pages={123–127} }
 @article{moering_ma_malkin_yang_zhu_mathaudhu_2016, title={Synergetic strengthening far beyond rule of mixtures in gradient structured aluminum rod}, volume={122}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2016.05.006}, abstractNote={Gradient structured metals have been reported to exhibit high strength and high ductility. Here we report that the strength of gradient structured aluminum rod is much higher than the value calculated using the rule of mixtures. The mechanical incompatibility in the gradient structured round sample produced 3D stress states, extraordinary strengthening and good ductility. An out of plane {111} wire texture was developed during the testing, which contributes to the evolution of the stress state and mechanical behavior.}, journal={SCRIPTA MATERIALIA}, author={Moering, Jordan and Ma, Xiaolong and Malkin, Jacob and Yang, Muxin and Zhu, Yuntian and Mathaudhu, Suveen}, year={2016}, month={Sep}, pages={106–109} }
 @article{gu_zhu_mathaudhu_2015, title={A model for < c plus a & rang; dislocation transmission across nano-spaced parallel basal stacking faults in a HCP alloy}, volume={95}, ISSN={["1362-3036"]}, DOI={10.1080/09500839.2015.1008066}, abstractNote={We develop a model for recently observed 〈c + a〉 dislocation transmission across nano-spaced parallel basal stacking faults in hexagonal close-packed (HCP) Mg microcrystalline grains. The model theoretically predicts nanospace-dependent yield strength that is in good agreement with experimental data. Additionally, it theoretically predicts activation volume and strain rate sensitivity.}, number={1}, journal={PHILOSOPHICAL MAGAZINE LETTERS}, author={Gu, Pei and Zhu, Yuntian and Mathaudhu, Suveen N.}, year={2015}, month={Jan}, pages={58–66} }
 @article{ma_xu_zhou_moering_narayan_zhu_2015, title={Alloying effect on grain-size dependent deformation twinning in nanocrystalline Cu-Zn alloys}, volume={95}, ISSN={["1478-6443"]}, DOI={10.1080/14786435.2014.1000418}, abstractNote={Grain-size dependency of deformation twinning has been previously reported in nanocrystalline face-centred-cubic metals, which results in an optimum grain-size range for twin formation. Here, we report, for the first time in experiments, the observed optimum grain sizes for deformation twins in nanocrystalline Cu–Zn alloys which slightly increase with increasing Zn content. This result agrees with the reported trend but is much weaker than predicted by stacking-fault-energy based models. Our results indicate that alloying changes the relationship between the stacking-fault and twin-fault energy and therefore affects the optimum grain size for deformation twinning. These observations should be also applicable to other alloy systems.}, number={3}, journal={PHILOSOPHICAL MAGAZINE}, author={Ma, X. L. and Xu, W. Z. and Zhou, H. and Moering, J. A. and Narayan, J. and Zhu, Y. T.}, year={2015}, month={Jan}, pages={301–310} }
 @article{tao_chen_jian_wang_zhu_zhu_langdon_2015, title={Anneal hardening of a nanostructured Cu-Al alloy processed by high-pressure torsion and rolling}, volume={628}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2015.01.055}, abstractNote={Abstract A Cu–7 wt% Al alloy was processed by high-pressure torsion and rolling to obtain nanostructure and then annealed at a series of different temperatures. Annealing at 250 °C for 120 min produced higher strength, which is attributed to the formation of nanoscale annealing twins. It is proposed that the high densities of stacking faults and nonequilibrium grain boundaries, combined with the high residual shear stresses in the deformed samples, contribute to the development of nanoscale annealing twins during the recrystallization process.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Tao, Jingmei and Chen, Guangming and Jian, Weiwei and Wang, Jun and Zhu, Yuntian and Zhu, Xinkun and Langdon, Terence G.}, year={2015}, month={Mar}, pages={207–215} }
 @article{an_zhu_cao_kawasaki_liao_ringer_nie_langdon_zhu_2015, title={Atomic-scale investigation of interface-facilitated deformation twinning in severely deformed Ag-Cu nanolamellar composites}, volume={107}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4926370}, DOI={10.1063/1.4926370}, abstractNote={We report an atomic-scale investigation of interface-facilitated deformation twinning behaviour in Ag-Cu nanolamellar composites. Profuse twinning activities in Ag supply partial dislocations to directly transmit across the Ag-Cu lamellar interface that promotes deformation twinning in the neighbouring Cu lamellae although the interface is severely deformed. The trans-interface twin bands change the local structure at the interface. Our analysis suggests that the orientation relationship and interfacial structure between neighbouring Ag-Cu lamellae play a crucial role in such special interface-facilitated twinning behaviour.}, number={1}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={An, X. H. and Zhu, S. M. and Cao, Y. and Kawasaki, M. and Liao, X. Z. and Ringer, S. P. and Nie, J. F. and Langdon, T. G. and Zhu, Y. T.}, year={2015}, month={Jul}, pages={011901} }
 @article{an_zhu_cao_kawasaki_liao_ringer_nie_langdon_zhu_2015, title={Atomic-scale investigation of interface-facilitated deformation twinning in severely deformed Ag-Cu nanolamellar composites}, volume={107}, number={1}, journal={Applied Physics Letters}, author={An, X. H. and Zhu, S. M. and Cao, Y. and Kawasaki, M. and Liao, X. Z. and Ringer, S. P. and Nie, J. F. and Langdon, T. G. and Zhu, Y. T.}, year={2015} }
 @article{zhou_cheng_ma_xu_mathaudhu_wang_zhu_2015, title={Effect of Ag on interfacial segregation in Mg-Gd-Y-(Ag)-Zr alloy}, volume={95}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2015.05.020}, abstractNote={Interfaces such as twin boundaries, stacking faults and grain boundaries often play an important role in controlling mechanical properties of metals through interaction with dislocations. Segregation of alloy elements and impurities to these interfaces can stabilize them and produce a large strengthening effect. Here we report the effect of Ag on segregation of alloy elements at twin boundaries, stacking faults and grain boundaries in the Mg–Gd system. Specifically, for the first time a spinal-shaped periodic segregation is observed at the {1 0 1¯ 2} twin boundary and high-angle lamellar grain boundary in the Mg–Gd–Y–Zr alloy due to the presence of the Ag addition. The segregation consists of Gd- and Ag-rich columns. It appears that high Ag content in the spinal-shaped segregation induces fcc-like cell structures.}, journal={ACTA MATERIALIA}, author={Zhou, H. and Cheng, G. M. and Ma, X. L. and Xu, W. Z. and Mathaudhu, S. N. and Wang, Q. D. and Zhu, Y. T.}, year={2015}, month={Aug}, pages={20–29} }
 @article{wu_li_ding_liu_zhao_zhu_2016, title={Effect of charge redistribution factor on stacking-fault energies of Mg-based binary alloys}, volume={112}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2015.09.023}, abstractNote={The energies of deformation fault (I2) and twin-like fault (T2) of thirteen binary Mg alloys were studied using density functional theory. It is shown that the faulted regions are energetically favorable for solute segregation, and the reduction of stacking-fault energy (SFE) was caused by charge redistribution. We define a charge redistribution factor, F, to quantify the solute-induced charge redistribution. An analytical model was established to calculate SFE from F.}, journal={SCRIPTA MATERIALIA}, author={Wu, Y. F. and Li, S. and Ding, Z. G. and Liu, W. and Zhao, Y. H. and Zhu, Y. T.}, year={2016}, month={Feb}, pages={101–105} }
 @article{li_jiang_zhao_ma_wen_zhu_2015, title={Effect of equal-channel angular pressing and aging on corrosion behavior of ZK60 Mg alloy}, volume={25}, ISSN={["2210-3384"]}, DOI={10.1016/s1003-6326(15)64038-9}, abstractNote={Commercial ZK60 Mg alloy was processed by multi-pass equal-channel angular pressing (ECAP) and subsequent aging to investigate the effect of grain refinement and second-phase redistribution on its corrosion behavior. Electrochemical tests show that the fine-grained samples after more ECAP passes have higher corrosion current densities (Jcorr) in the polarization curves, lower charge-transfer resistance (Rt) values in the EIS plots. The severe plastic deformation decreases the alloy corrosion resistance besides the well-known strengthening and toughening. Scanning Kelvin probe (SKP) measurement shows that the anodic and cathode sites are homogeneously distributed on the surface of the fine-grained alloy, which inhibits localized corrosion. The SKP potential, having linear relationship with the corrosion potential (φcorr), decreases with increasing the ECAP pass. Furthermore, the post-ECAP aging can slightly improve the corrosion resistance of the fine-grained ZK60 Mg alloy and enhance the comprehensive performances, due to the stress relief and uniform distribution of second-phase particles.}, number={12}, journal={TRANSACTIONS OF NONFERROUS METALS SOCIETY OF CHINA}, author={Li, Xin and Jiang, Jing-hua and Zhao, Yong-hao and Ma, Ai-bin and Wen, Dao-jing and Zhu, Yun-tian}, year={2015}, month={Dec}, pages={3909–3920} }
 @article{xu_li_valdez_saber_zhu_koch_scattergood_2016, title={Effect of nano-oxide particle size on radiation resistance of iron-chromium alloys}, volume={469}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2015.11.044}, abstractNote={Radiation resistance of Fe–14Cr alloys under 200 keV He irradiation at 500 °C was systematically investigated with varying sizes of nano oxide Zr, Hf and Cr particles. It is found that these nano oxide particles acted as effective sites for He bubble formation. By statistically analyzing 700–1500 He bubbles at the depth of about 150–700 nm from a series of HRTEM images for each sample, we established the variation of average He bubble size, He bubble density, and swelling percentage along the depth, and found them to be consistent with the He concentration profile calculated from the SIRM program. Oxide particles with sizes less than 3.5–4 nm are found most effective for enhancing radiation resistance in the studied alloy systems.}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Xu, Weizong and Li, Lulu and Valdez, James A. and Saber, Mostafa and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2016}, month={Feb}, pages={72–81} }
 @article{wu_zheng_cai_yao_zhu_narayan_2015, title={Fabrication of epitaxial Cu3Ge on sapphire with controlled crystallinity and planar defects}, volume={641}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2015.03.143}, abstractNote={In this paper, we report the growth of epitaxial Cu3Ge thin films on c-plane sapphire substrate through domain matching epitaxy. Systematic study on the crystallinity of Cu3Ge thin films is carried out to correlate epitaxial characteristics with substrate lattice misfit. The crystallinity and epitaxy of the as-grown Cu3Ge thin films are improved considerably by controlling the parameters of pulsed laser deposition. The epitaxial characteristics and formation of twins in Cu3Ge are investigated and a mechanism of twin formation in Cu3Ge ε1-phase is discussed. The present study proves that the crystallinity and defect structure of Cu3Ge thin film can be controlled by adjusting the deposition parameters. It serves as a fundamental research for future applications of epitaxial Cu3Ge as metallization material in semiconductor industry.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Wu, F. and Zheng, J. K. and Cai, W. and Yao, N. and Zhu, Y. T. and Narayan, J.}, year={2015}, month={Aug}, pages={238–243} }
 @article{valiev_estrin_horita_langdon_zehetbauer_zhu_2016, title={Fundamentals of Superior Properties in Bulk NanoSPD Materials}, volume={4}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2015.1060543}, abstractNote={Bulk nanoSPD materials are materials with nanostructural features, such as nanograins, nanoclusters, or nanotwins, produced by severe plastic deformation (SPD) techniques. Such nanostructured materials are fully dense and contamination free and in many cases they have superior mechanical and functional properties. Here, we provide a critical overview of such materials, with a focus on the fundamentals for the observed extraordinary properties. We discuss the unique nanostructures that lead to the superior properties, the underlying deformation mechanisms, the critical issues that remain to be investigated, future research directions, and the application potential of such materials.}, number={1}, journal={MATERIALS RESEARCH LETTERS}, author={Valiev, R. Z. and Estrin, Y. and Horita, Z. and Langdon, T. G. and Zehetbauer, M. J. and Zhu, Y. T.}, year={2016}, pages={1–21} }
 @article{cao_wang_an_liao_kawasaki_ringer_langdon_zhu_2015, title={Grain boundary formation by remnant dislocations from the de-twinning of thin nano-twins}, volume={100}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2015.01.001}, abstractNote={We report a grain boundary formation mechanism in face-centred cubic metals with low stacking fault energies. Severe plastic deformation produces primary nano-twins with a twin boundary spacing of several nanometres, followed by secondary twinning through the activation of Shockley partial dislocations. The partial dislocations interact with primary twin boundaries, resulting in de-twinning of the primary twins and producing very high densities of sessile dislocations. The accumulation of these dislocations produces new grain boundaries with neighbouring grains having similar orientations.}, journal={SCRIPTA MATERIALIA}, author={Cao, Y. and Wang, Y. B. and An, X. H. and Liao, X. Z. and Kawasaki, M. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2015}, month={Apr}, pages={98–101} }
 @article{wu_yang_yuan_wu_wei_huang_zhu_2015, title={Heterogeneous lamella structure unites ultrafine-grain strength with coarse-grain ductility}, volume={112}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.1517193112}, abstractNote={Significance
          For centuries it has been a challenge to avoid strength–ductility trade-off, which is especially problematic for ultrastrong ultrafine-grained metals. Here we evade this trade-off dilemma by architecting a heterogeneous lamella structure, i.e., soft micrograined lamellae embedded in hard ultrafine-grained lamella matrix. The heterogeneous deformation of this previously unidentified structure produces significant back-stress hardening in addition to conventional dislocation hardening, rendering it higher strain hardening than coarse-grained metals. The high back-stress hardening makes the material as strong as ultrafine-grained metals and as ductile as coarse-grained metals.}, number={47}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Wu, Xiaolei and Yang, Muxin and Yuan, Fuping and Wu, Guilin and Wei, Yujie and Huang, Xiaoxu and Zhu, Yuntian}, year={2015}, month={Nov}, pages={14501–14505} }
 @article{yang_ma_moering_zhou_wang_gong_tao_zhu_zhu_2015, title={Influence of gradient structure volume fraction on the mechanical properties of pure copper}, volume={645}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2015.08.037}, abstractNote={This paper reports the influence of gradient structure volume fraction on the tensile mechanical behaviors of pure copper processed by surface mechanical attrition treatment at cryogenic temperature. Superior combinations of tensile strength and ductility are observed in a certain volume fraction, in which strain hardening uprising after yielding is also observed. The gradient structure produces a synergetic strengthening and extra work hardening. These findings suggest the existence of an optimum volume fraction of gradient structure for the best mechanical properties.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Yang, Xincheng and Ma, Xiaolong and Moering, Jordan and Zhou, Hao and Wang, Wei and Gong, Yulan and Tao, Jingmei and Zhu, Yuntian and Zhu, Xinkun}, year={2015}, month={Oct}, pages={280–285} }
 @article{li_xu_saber_zhu_koch_scattergood_2015, title={Influence of scandium addition on the high-temperature grain size stabilization of oxide-dispersion-strengthened (ODS) ferritic alloy}, volume={636}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2015.03.117}, abstractNote={The influence of 1–4 at% Sc addition on the thermal stability of mechanically alloyed ODS ferritic alloy was studied in this work. Sc addition was found to significantly stabilize grain size and microhardness at high temperatures. Grain sizes of samples with 1 and 4 at% Sc was found maintained in the nanoscale range at temperatures up to 1000 °C with hardness maintained at 5.6 and 6.7 GPa, respectively. The detailed microstructure was also investigated from EDS elemental mapping, where nanofeatures [ScTiO] were observed, while nanosized [YTiO] particles were rarely seen. This is probably due to the concentration difference between Sc and Y, leading to the formation of [ScTiO] favoring that of [YTiO]. Precipitation was considered as the major source for the observed high temperature stabilization. In addition, 14YT–Sc alloys without large second phases such as Ti-oxide can exhibit better performance compared to conventional ODS materials.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Lulu and Xu, Weizong and Saber, Mostafa and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2015}, month={Jun}, pages={565–571} }
 @article{li_xu_saber_zhu_koch_scattergood_2015, title={Long-term stability of 14YT-4Sc alloy at high temperature}, volume={647}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2015.09.012}, abstractNote={14YT alloy (Fe–14Cr–0.25wt%Y2O3–0.4wt%Ti) with 4 at% Sc addition was previously reported to exhibit a nanoscale microstructure and high strength when annealed at temperatures up to 1000 °C (0.65Tm) for 1 h. Here we report that the microstructure and mechanical behavior of 14YT–4Sc alloy after long-term annealing for up to 60 h at 1000 °C. FIB analysis shows abnormal grain growth with annealing time, while a large fraction of the matrix still consists of nanoscale grains. TEM images reveal a slight growth of nano grains, with estimated grain growth exponent, n, to be 0.29. Sc–Ti–Y–O enriched nano oxide particles (<10 nm) were observed in EDS mapping of the 14YT–4Sc–60h sample. The nano-structure retention at the high temperature of 1000 °C for 60 h is attributed to these complex nano oxides.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Lulu and Xu, Weizong and Saber, Mostafa and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2015}, month={Oct}, pages={222–228} }
 @article{zhang_wang_li_li_bradford_zhu_2016, title={Microcombing enables high-performance carbon nanotube composites}, volume={123}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2015.12.012}, abstractNote={A processing approach, microcombing, has been reported recently to produce dry carbon nanotube (CNT) films with superior mechanical and electrical properties by taking advantage of its efficiency in straightening the wavy CNTs and aligning the strands. Here, we report the fabrication of CNT composite films with aligned CNTs and CNT strands, reduced waviness, high CNT weight fraction, and relatively uniform CNT distribution, using poly(vinyl alcohol) (PVA) as a model matrix. These structural features give the micro-combed CNT/PVA composite films electrical conductivity of 1.84 × 105 S/m, Young's modulus of 119 GPa, tensile strength of 2.9 GPa, and toughness of 52.4 J/cm3, which improve over those of uncombed samples by 300%, 100%, 120%, and 200%, respectively, and are also much higher than those obtained by other processing approaches. Moreover, this method is expected to be applicable to various polymer matrices as long as they can be dissolved in the solution.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Zhang, Liwen and Wang, Xin and Li, Ru and Li, Qingwen and Bradford, Philip D. and Zhu, Yuntian}, year={2016}, month={Feb}, pages={92–98} }
 @article{xu_li_saber_koch_zhu_scattergood_2015, title={Microstructures and Stabilization Mechanisms of Nanocrystalline Iron-Chromium Alloys with Hafnium Addition}, volume={46A}, ISSN={["1543-1940"]}, DOI={10.1007/s11661-015-2985-2}, number={9}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Xu, Weizong and Li, Lulu and Saber, Mostafa and Koch, Carl C. and Zhu, Yuntian and Scattergood, Ronald O.}, year={2015}, month={Sep}, pages={4394–4404} }
 @article{ma_zhou_narayan_zhu_2015, title={Stacking-fault energy effect on zero-strain deformation twinning in nanocrystalline Cu-Zn alloys}, volume={109}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2015.07.027}, abstractNote={It has been reported that most deformation twins in nanocrystalline face-centered-cubic metals do not produce macroscopic strain. Here we report the decrease of zero-strain deformation twinning with decreasing stacking-fault energy. One of the two major mechanisms that produce zero-strain twinning is cooperative slip of three partials under external applied stress. Lower stacking-fault energy weakens this mechanism and statistically reduces the fraction of twins with zero-strain.}, journal={SCRIPTA MATERIALIA}, author={Ma, X. L. and Zhou, H. and Narayan, J. and Zhu, Y. T.}, year={2015}, month={Dec}, pages={89–93} }
 @article{ma_huang_xu_zhou_wu_zhu_2015, title={Strain hardening and ductility in a coarse-grain/nanostructure laminate material}, volume={103}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2015.03.006}, abstractNote={A laminate structure with a nanostructured Cu–10Zn layer sandwiched between two coarse-grained Cu layers was produced by high-pressure torsion, rolling and annealing. Sharp interlayer interfaces with sufficient bonding strength were developed. Mechanical incompatibility between different layers during tensile deformation produced high strain hardening, which led to a tensile ductility higher than prediction by the rule-of-mixture. These observations provide insights into the architectural design and deformation studies of materials with gradient and laminate structures.}, journal={SCRIPTA MATERIALIA}, author={Ma, X. L. and Huang, C. X. and Xu, W. Z. and Zhou, H. and Wu, X. L. and Zhu, Y. T.}, year={2015}, month={Jul}, pages={57–60} }
 @article{zhang_wang_xu_zhang_li_bradford_zhu_2015, title={Strong and Conductive Dry Carbon Nanotube Films by Microcombing}, volume={11}, ISSN={["1613-6829"]}, DOI={10.1002/smll.201500111}, abstractNote={In order to maximize the carbon nanotube (CNT) buckypaper properties, it is critical to improve their alignment and reduce their waviness. In this paper, a novel approach, microcombing, is reported to fabricate aligned CNT films with a uniform structure. High level of nanotube alignment and straightness was achieved using sharp surgical blades with microsized features at the blade edges to comb single layer of CNT sheet. These microcombs also reduced structural defects within the film and enhanced the nanotube packing density. Following the microcombing approach, the as‐produced CNT films demonstrated a tensile strength of up to 3.2 GPa, Young's modulus of up to 172 GPa, and electrical conductivity of up to 1.8 × 105 S m−1, which are much superior to previously reported CNT films or buckypapers. More importantly, this novel technique requires less rigorous process control and can construct CNT films with reproducible properties.}, number={31}, journal={SMALL}, author={Zhang, Liwen and Wang, Xin and Xu, Weizong and Zhang, Yongyi and Li, Qingwen and Bradford, Philip D. and Zhu, Yuntian}, year={2015}, month={Aug}, pages={3830–3836} }
 @article{yuan_ma_gou_jiang_lu_song_zhu_2015, title={Superior mechanical properties of ZK60 mg alloy processed by equal channel angular pressing and rolling}, volume={630}, ISSN={["1873-4936"]}, url={https://doi.org/10.1016/j.msea.2015.02.004}, DOI={10.1016/j.msea.2015.02.004}, abstractNote={A superior combination of ultrahigh strength and good ductility was achieved in ZK60 Mg alloy sheet processed by equal Channel Angular Pressing (ECAP) and subsequent cold rolling. The cold rolling almost doubled the yield strength while retaining moderate ductility. The ultrahigh strength was attributed to the ultrafine-grained structure with high density of dislocations. Nano-spaced parallel deformation strips were also observed and contributed to strength and strain hardening. The fine structure and non-basal texture of the rolled sheet rendered good ductility.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, publisher={Elsevier BV}, author={Yuan, Yuchun and Ma, Aibin and Gou, Xiaofan and Jiang, Jinghua and Lu, Fumin and Song, Dan and Zhu, Yuntian}, year={2015}, month={Apr}, pages={45–50} }
 @article{moering_ma_chen_miao_li_qian_mathaudhu_zhu_2015, title={The role of shear strain on texture and microstructural gradients in low carbon steel processed by Surface Mechanical Attrition Treatment}, volume={108}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2015.06.027}, abstractNote={In this study, the shear strain at various depths of a low carbon steel processed by Surface Mechanical Attrition Treatment (SMAT) was measured using deformed carbide bands as internal strain markers. The shear strain gradient is found to strongly correlate with the gradients of texture, microstructure and hardness. The microhardness increases approximately linearly with shear strain, but deviates at the top surface. In the top surface, the average ferrite grain size is reduced to 60 nm with a strong {1 1 0}//SMAT surface texture.}, journal={SCRIPTA MATERIALIA}, author={Moering, Jordan and Ma, Xiaolong and Chen, Guizhen and Miao, Pifeng and Li, Guozhong and Qian, Gang and Mathaudhu, Suveen and Zhu, Yuntian}, year={2015}, month={Nov}, pages={100–103} }
 @article{faraji_stano_yildiz_li_zhu_bradford_2015, title={Ultralight anisotropic foams from layered aligned carbon nanotube sheets}, volume={7}, ISSN={["2040-3372"]}, DOI={10.1039/c5nr03899e}, abstractNote={A novel nanofabrication method is demonstrated to produce large size, elastically resilient, ultra-low density carbon nanotube foams (3.8 mg cm−3) with anisotropic and tunable properties. Potential applications of this unique material are explored.}, number={40}, journal={NANOSCALE}, author={Faraji, Shaghayegh and Stano, Kelly L. and Yildiz, Ozkan and Li, Ang and Zhu, Yuntian and Bradford, Philip D.}, year={2015}, pages={17038–17047} }
 @article{wu_li_cao_pan_zhu_2016, title={Ultraviolet light irradiation on pitting corrosion of Cu-based bulk metallic glasses}, volume={661}, ISSN={["1873-4669"]}, DOI={10.1016/j.jallcom.2015.11.189}, abstractNote={We report the observation that UV irradiation substantially improves pitting corrosion resistance of Cu-based bulk metallic glasses. Specifically, two Cu-based bulk metallic glasses in this study showed more stable passive films under UV irradiation than under irradiation-free condition when polarized in 3.5 wt.% NaCl aqueous solution. This finding indicates that Cu-based bulk metallic glasses are promising to serve in high UV irradiation and corrosive environments.}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={Wu, Jili and Li, Xingzhou and Cao, Hongbo and Pan, Ye and Zhu, Yuntian}, year={2016}, month={Mar}, pages={345–348} }
 @article{zhou_xu_jian_cheng_ma_guo_mathaudhu_wang_zhu_2014, title={A new metastable precipitate phase in Mg-Gd-Y-Zr alloy}, volume={94}, ISSN={["1478-6443"]}, DOI={10.1080/14786435.2014.913115}, abstractNote={Mg–RE alloys are among the strongest Mg-based alloys due to their unique precipitation structures. A previously unobserved metastable phase (βT) is found to coexist with reported β″ and β′ metastable phases under peak ageing conditions in a Mg–Gd–Y–Zr alloy. The position of the RE elements within the βT phase is identified using atomic-resolution high-angle annular dark field scanning transmission electron microscopy imaging, and the βT phase is shown to have an orthorhombic structure with a stoichiometry of Mg5RE. Based on these observations, a new precipitation sequence is proposed.}, number={21}, journal={PHILOSOPHICAL MAGAZINE}, author={Zhou, H. and Xu, W. Z. and Jian, W. W. and Cheng, G. M. and Ma, X. L. and Guo, W. and Mathaudhu, S. N. and Wang, Q. D. and Zhu, Y. T.}, year={2014}, pages={2403–2409} }
 @article{huang_hu_wang_wang_yang_zhu_2015, title={An Ideal Ultrafine-Grained Structure for High Strength and High Ductility}, volume={3}, ISSN={["2166-3831"]}, DOI={10.1080/21663831.2014.968680}, abstractNote={An ideal ultrafine-grained (UFG) microstructure for high strength and high ductility should have short dislocation-slip path to impede dislocation slip and very low dislocation density to ensure more room for dislocation accumulation. Such a microstructure is hard to produce, especially for UFG metals produced by severe plastic deformation techniques. Here, we report an ideal UFG structure produced by reverse transformation of deformation-induced martensite in 304 L austenitic stainless steel. It produced small grains and a high density of nanotwins for both high strength and high ductility. This approach is applicable to face-centered cubic metals with low stacking fault energy.}, number={2}, journal={MATERIALS RESEARCH LETTERS}, author={Huang, C. X. and Hu, W. P. and Wang, Q. Y. and Wang, C. and Yang, G. and Zhu, Y. T.}, year={2015}, pages={88–94} }
 @article{di_wang_xing_zhang_zhang_lu_li_zhu_2014, title={Dry-Processable Carbon Nanotubes for Functional Devices and Composites}, volume={10}, ISSN={1613-6810}, url={http://dx.doi.org/10.1002/SMLL.201401465}, DOI={10.1002/SMLL.201401465}, abstractNote={Assembly of carbon nanotubes (CNTs) in effective and productive ways is of vital importance to their application. Recent progress in synthesis of CNTs has inspired new strategies for utilizing the unique physiochemical properties of CNTs in macroscale materials and devices. Assembling CNTs by dry processes (e.g., directly collecting CNTs in the form of freestanding films followed by pressing, stretching, and multilayer stacking instead of dispersing them in solution) not only considerably simplifies the processes but also avoids structural damage to the CNTs. Various dry‐processable CNTs are reviewed, focusing on their synthesis, properties, and applications. The synthesis techniques are organized in terms of aggregative morphologies and microstructure control of CNTs. Important applications such as functional thin‐film devices, strong CNT films, and composites are included. The opportunities and challenges in the synthesis techniques and fabrication of advanced composites and devices are discussed.}, number={22}, journal={Small}, publisher={Wiley}, author={Di, Jiangtao and Wang, Xin and Xing, Yajuan and Zhang, Yongyi and Zhang, Xiaohua and Lu, Weibang and Li, Qingwen and Zhu, Yuntian T.}, year={2014}, month={Aug}, pages={4606–4625} }
 @misc{di_wang_xing_zhang_zhang_lu_li_zhu_2014, title={Dry-processable carbon nanotubes for functional devices and composites}, volume={10}, number={22}, journal={Small (Weinheim An Der Bergstrasse, Germany)}, author={Di, J. T. and Wang, X. and Xing, Y. J. and Zhang, Y. Y. and Zhang, X. H. and Lu, W. B. and Li, Q. W. and Zhu, Y. T. T.}, year={2014}, pages={4606–4625} }
 @article{xu_zhang_cheng_jian_millett_koch_mathaudhu_zhu_2014, title={Dynamic Void Growth and Shrinkage in Mg under Electron Irradiation}, volume={2}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2014.904826}, DOI={10.1080/21663831.2014.904826}, abstractNote={We report in situ atomic-scale investigation of late-stage void evolution, including growth, coalescence and shrinkage, under electron irradiation. With increasing irradiation dose, the total volume of voids increased linearly, while the nucleation rate of new voids decreased slightly and the total number of voids decreased. Some voids continued to grow while others shrank to disappear, depending on the nature of their interactions with nearby self-interstitial loops. For the first time, surface diffusion of adatoms was observed to be largely responsible for the void coalescence and thickening. These findings provide fundamental understanding to help with the design and modeling of irradiation-resistant materials.}, number={3}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Xu, W. Z. and Zhang, Y. F. and Cheng, G. M. and Jian, W. W. and Millett, P. C. and Koch, C. C. and Mathaudhu, S. N. and Zhu, Y. T.}, year={2014}, month={Apr}, pages={176–183} }
 @article{ni_liao_zhu_2014, title={Effect of severe plastic deformation on the structure and mechanical properties of bulk nanocrystalline metals}, volume={50}, number={2}, journal={Acta Metallurgica Sinica}, author={Ni, S. and Liao, X. Z. and Zhu, Y. T.}, year={2014}, pages={156–168} }
 @article{wu_jiang_chen_yuan_zhu_2014, title={Extraordinary strain hardening by gradient structure}, volume={111}, ISSN={["0027-8424"]}, DOI={10.1073/pnas.1324069111}, abstractNote={Significance
          Nature creates the gradient structure (GS) for a purpose: to make biological systems strong and tough to survive severe natural forces. For the grain-size GS, the deformation physics is still unclear. One wonders if the grain-size GS in the nanomicroscale would also benefit materials engineered by mankind. In this paper, a universal strain hardening mechanism is revealed in the GS. We discovered a unique extra strain hardening that is intrinsic to the GS. Its mechanism is the presence of strain gradient together with the stress state change. A superior combination of strength and ductility that is not accessible to conventional homogeneous materials is obtained. As a novel mechanism, extra strain hardening renders high ductility in the GS materials.}, number={20}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={Wu, XiaoLei and Jiang, Ping and Chen, Liu and Yuan, Fuping and Zhu, Yuntian T.}, year={2014}, month={May}, pages={7197–7201} }
 @article{li_saber_xu_zhu_koch_scattergood_2014, title={High-temperature grain size stabilization of nanocrystalline Fe-Cr alloys with Hf additions}, volume={613}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2014.06.099}, abstractNote={The influence of 1–4 at% Hf additions on the thermal stability of mechanically alloyed nanocrystalline Fe–14Cr alloys was studied in this work. XRD-calculated grain size and microhardness results were reported versus isochronal annealing treatments up to 1100 °C. Microstructural evolution was investigated using channeling contrast FIB imaging and TEM. Grain size of samples with 4 at% Hf was found to be maintained in the nanoscale range at temperatures up to 1000 °C. Zener pinning was considered as a major source of high temperature grain size stabilization. By comparing the Orowan strengthening contribution to the total hardness, the deviation of grain size predictions from the actual grain size in Fe–14Cr–4Hf suggests the presence of thermodynamic stabilization by the solute segregation to grain boundaries (GBs). A predictive thermodynamic model indicates that the thermodynamic stabilization can be expected.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Lulu and Saber, Mostafa and Xu, Weizong and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2014}, month={Sep}, pages={289–295} }
 @article{zhou_wang_faraji_bradford_li_zhu_2014, title={Mechanical and electrical properties of aligned carbon nanotube/carbon matrix composites}, volume={75}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2014.04.008}, abstractNote={To synthesize carbon nanotube/carbon matrix (CNT/C) composites rivaling or exceeding the mechanical and electrical properties of current carbon fiber/carbon matrix composites, it is essential to align carbon nanotubes in the composite. In this work, we fabricated CNT/polyacrylonitrile (PAN) precursor composites with high degree of CNT alignment, and carbonized and graphitized them at high temperatures. Carbonizing the precursor composites significantly improved their elastic modulus, strength, and electrical conductivity. The matrix was uniformly carbonized and highly graphitized. The excellent mechanical and electrical properties make the CNT/C composites promising for many high temperature aerospace applications.}, journal={CARBON}, author={Zhou, Zhou and Wang, Xin and Faraji, Shaghayegh and Bradford, Philip D. and Li, Qingwen and Zhu, Yuntian}, year={2014}, month={Aug}, pages={307–313} }
 @article{xu_li_saber_koch_zhu_scattergood_2014, title={Nano ZrO2 particles in nanocrystalline Fe-14Cr-1.5Zr alloy powders}, volume={452}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2014.05.067}, abstractNote={Here we report on the formation of nano ZrO2 particles in Fe–14Cr–1.5Zr alloy powders synthesized by mechanical alloying. The nano ZrO2 particles were found uniformly dispersed in the ferritic matrix powders with an average size of about 3.7 nm, which rendered the alloy powders so stable that it retained nanocrystalline structure after annealing at 900 °C for 1 h. The ZrO2 nanoparticles have a tetragonal crystal structure and the following orientation relationship with the matrix: (0 0 2)ZrO2//(0 0 2)Matrix and [0 1 0]ZrO2//[1 2 0]Matrix. The size and dispersion of the ZrO2 particles are comparable to those of Y–Ti–O enriched oxides reported in irradiation-resistant ODS alloys. This suggests a potential application of the new alloy powders for nuclear energy applications.}, number={1-3}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Xu, W. Z. and Li, L. L. and Saber, M. and Koch, C. C. and Zhu, Y. T. and Scattergood, R. O.}, year={2014}, month={Sep}, pages={434–439} }
 @article{piyawit_xu_mathaudhu_freudenberger_rigsbee_zhu_2014, title={Nucleation and growth mechanism of Ag precipitates in a CuAgZr alloy}, volume={610}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2014.05.023}, abstractNote={CuAgZr alloy is a variant of the CuAg alloy that is developed for high strength and high conductivity applications. Its strengthening is accomplished mainly by the precipitation of Ag precipitates, which tend to align on {111} planes in the Cu matrix. This alignment has been reported to be caused by stacking faults on {111} planes. Contrary to these reports, this research presents evidence for Ag precipitates formation on {111} planes due to the minimization of elastic energy. The Ag precipitates were formed by clustering of Ag atoms while maintaining the fcc crystal structure of the matrix. They have faceted {111} interfaces with the matrix. The thickening of precipitates appears to be by the ledge growth mechanism, which is resulted in by misfit dislocation networks on the interface.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Piyawit, W. and Xu, W. Z. and Mathaudhu, S. N. and Freudenberger, J. and Rigsbee, J. M. and Zhu, Y. T.}, year={2014}, month={Jul}, pages={85–90} }
 @article{mathaudhu_estrin_horita_lavernia_liao_lu_wei_wilde_zhu_2014, title={Preface to the special issue on ultrafine-grained materials}, volume={49}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-014-8393-y}, abstractNote={[mathaudhu, suveen n.] us army, res off, res triangle pk, nc 27709 usa. [estrin, yuri] monash univ, clayton, vic, australia. [horita, zenji] kyushu univ, fukuoka 812, japan. [lavernia, enrique] univ calif davis, davis, ca 95616 usa. [liao, xiao zhou] univ sydney, sydney, nsw 2006, australia. [lu, lei] acad sinica, inst met res, shenyang 110015, peoples r china. [wei, qiuming] univ n carolina, charlotte, nc 28223 usa. [wilde, gerhard] univ munster, d-48149 munster, germany. [zhu, yun tian] n carolina state univ, raleigh, nc 27695 usa.}, number={19}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Mathaudhu, Suveen N. and Estrin, Yuri and Horita, Zenji and Lavernia, Enrique and Liao, Xiao Zhou and Lu, Lei and Wei, Qiuming and Wilde, Gerhard and Zhu, Yun Tian}, year={2014}, month={Oct}, pages={6485–6486} }
 @article{saber_xu_li_zhu_koch_scattergood_2014, title={Size effect of primary Y2O3 additions on the characteristics of the nanostructured ferritic ODS alloys: Comparing as-milled and as-milled/annealed alloys using S/TEM}, volume={452}, ISSN={["1873-4820"]}, DOI={10.1016/j.jnucmat.2014.05.014}, abstractNote={The need for providing S/TEM evidence to clarify the mechanisms of nano-scale precipitate formation was the motivation of this investigation. In this study, an Fe–14Cr–0.4Ti alloy was ball-milled with different amounts of Y2O3 content up to 10 wt.%, and then annealed at temperatures up to 1100 °C. Micron-size Y2O3 particles were substituted for the nano-size counterpart to elucidate the mechanism of oxide precipitate formation. The S/TEM studies revealed that the microstructure of the alloy with 10 wt.% yttria contained amorphous undissolved Y2O3 after ball milling, while a small part of the initial oxide particles were dissolved into the solid solution. Consequently, when the amount of yttria was reduced to 1 wt.%, the amorphous phase of the yttria vanished and the whole content of Y2O3 was dissolved into the BCC solid solution. Defect analysis of precipitates on the annealed samples via S/TEM and micro-hardness studies revealed that the use of micron-size primary oxide particles can produce nano-size precipitates, stable up to temperatures as high as 1100 °C, and uniformly distributed throughout the microstructure. This study indicates that the use of high energy ball milling along with micron-size primary oxide particles can lead to nanostructured ferritic ODS alloys without the use of nano-size primary oxide additions.}, number={1-3}, journal={JOURNAL OF NUCLEAR MATERIALS}, author={Saber, Mostafa and Xu, Weizong and Li, Lulu and Zhu, Yuntian and Koch, Carl C. and Scattergood, Ronald O.}, year={2014}, month={Sep}, pages={223–229} }
 @article{gu_dao_zhu_2014, title={Strengthening at nanoscaled coherent twin boundary in f.c.c. metals}, volume={94}, ISSN={["1478-6443"]}, DOI={10.1080/14786435.2014.885138}, abstractNote={This paper analyses slip transfer at the boundary of nanoscaled growth twins in face-centred cubic (f.c.c.) metals for strengthening mechanism. The required stress for slip transfer, i.e. inter-twin flow stress, is obtained in a simple expression in terms of stacking fault energy and/or twin boundary (TB) energy, constriction energy and activation volume. For nanotwinned Al, Cu and Ni, inter-twin flow stress versus twin thickness remarkably shows Hall–Petch relationship. The Hall–Petch slope is rationalized for various reactions of screw and non-screw dislocations at the TB. Additionally, strengthening at the boundary of nanoscaled deformation twins in f.c.c. metals is analysed by evaluating required twinning stress. At small nanograin size, the prediction of deformation twin growth stress shows inverse grain-size effect on twinning, in agreement with recent experimental finding.}, number={11}, journal={PHILOSOPHICAL MAGAZINE}, author={Gu, Pei and Dao, Ming and Zhu, Yuntian}, year={2014}, month={Apr}, pages={1249–1262} }
 @article{faraji_stano_rost_maria_zhu_bradford_2014, title={Structural annealing of carbon coated aligned multi-walled carbon nanotube sheets}, volume={79}, ISSN={0008-6223}, url={http://dx.doi.org/10.1016/J.CARBON.2014.07.049}, DOI={10.1016/J.CARBON.2014.07.049}, abstractNote={Sheets of aligned multi-walled carbon nanotubes (AMWCNTs) were used to study the structural annealing of pyrolytic carbon (PyC) coatings with various thicknesses on MWCNTs. PyC was deposited using chemical vapor infiltration and the thickness was controlled via the infiltration time. Structural annealing of the PyC coated AMWCNT (AMWCNT/C) sheets at 2150 °C provided different results for different thickness coatings. Transmission electron microscopy images showed that the carbon deposited from acetylene formed laminar PyC coatings, resembling rough tube walls, on the CNT surfaces. Following the high temperature heat treatment, coatings from short PyC deposition times changed their structure, resulting in radial growth of the MWCNTs. Raman and X-ray diffraction measurements also revealed that the radially grown MWCNTs had graphitic quality very close to pristine nanotubes after annealing. Electrical conductivity of AMWCNT/C sheets after high temperature heat treatment was twice that of pristine AMWCNT sheets. The focus of this study was to determine the PyC coating thickness at which a rough PyC coating would no longer change its structure into new CNT walls. The samples treated longer than 30 min had much more disordered PyC deposited on the surface and the additional material did not form additional tube walls after thermal annealing.}, journal={Carbon}, publisher={Elsevier BV}, author={Faraji, Shaghayegh and Stano, Kelly and Rost, Christina and Maria, Jon-Paul and Zhu, Yuntian and Bradford, Philip D.}, year={2014}, month={Nov}, pages={113–122} }
 @article{wu_jiang_chen_zhang_yuan_zhu_2014, title={Synergetic Strengthening by Gradient Structure}, volume={2}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2014.935821}, DOI={10.1080/21663831.2014.935821}, abstractNote={Gradient structures are characterized with a systematic change in microstructures on a macroscopic scale. Here, we report that gradient structures in engineering materials such as metals produce an intrinsic synergetic strengthening, which is much higher than the sum of separate gradient layers. This is caused by macroscopic stress gradient and the bi-axial stress generated by mechanical incompatibility between different layers. This represents a new mechanism for strengthening that exploits the principles of both mechanics and materials science. It may provide for a novel strategy for designing material structures with superior properties.}, number={4}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Wu, X. L. and Jiang, P. and Chen, L. and Zhang, J. F. and Yuan, F. P. and Zhu, Y. T.}, year={2014}, month={Jul}, pages={185–191} }
 @misc{wu_rao_prater_zhu_narayan_2014, title={Tuning exchange bias in epitaxial Ni/MgO/TiN heterostructures integrated on Si(100)}, volume={18}, ISSN={["1879-0348"]}, DOI={10.1016/j.cossms.2014.09.002}, abstractNote={Epitaxial Ni thin films are integrated with tunneling barrier MgO on Si(1 0 0) substrate. During pulsed laser deposition, early island-like structure transformed into uniform thin film with increasing number of laser pulses. This led to transitions in exchange bias from positive to negative and back to positive, which is ascribed to morphology associated residual strain. The Ni island structure has a coercive field as high as 3 times of that of the continuous film. The current work holds a tremendous promise in the realization of magnetic devices integrated with the Si-platform.}, number={5}, journal={CURRENT OPINION IN SOLID STATE & MATERIALS SCIENCE}, author={Wu, F. and Rao, S. S. and Prater, J. T. and Zhu, Y. T. and Narayan, J.}, year={2014}, month={Oct}, pages={263–268} }
 @article{schmidt_wang_zhu_sombers_2013, title={Carbon Nanotube Yarn Electrodes for Enhanced Detection of Neurotransmitter Dynamics in Live Brain Tissue}, volume={7}, ISSN={["1936-086X"]}, DOI={10.1021/nn402857u}, abstractNote={This work demonstrates the potential of nanoscale carbon electrode materials for improved detection of electroactive neurotransmitter dynamics in the brain. Individual multiwalled carbon nanotubes were synthesized via chemical vapor deposition, spun into yarns, and used in the fabrication of disk microelectrodes that were subsequently characterized using scanning electron and atomic force microscopies. The carbon nanotube yarn electrodes were coupled with fast-scan cyclic voltammetry and used to discriminately detect rapid neurotransmitter fluctuations in acute brain slices. The results demonstrate that the distinct structural and electronic properties of the nanotubes result in improved selectivity, sensitivity, and spatial resolution, as well as faster apparent electron transfer kinetics when compared to the conventional carbon-fiber microelectrodes typically used in vivo.}, number={9}, journal={ACS NANO}, author={Schmidt, Andreas C. and Wang, Xin and Zhu, Yuntian and Sombers, Leslie A.}, year={2013}, month={Sep}, pages={7864–7873} }
 @article{cao_wang_an_liao_kawasaki_ringer_langdon_zhu_2014, title={Concurrent microstructural evolution of ferrite and austenite in a duplex stainless steel processed by high-pressure torsion}, volume={63}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2013.09.030}, abstractNote={A duplex stainless steel with approximately equal volume fractions of ferrite and austenite was processed by high-pressure torsion. Nano-indentation, electron backscatter diffraction and transmission electron microscopy were used to investigate the hardness and microstructure evolutions of the steel. Despite the different strain-hardening rates of individual ferrite and austenite, the microstructures of the two phases evolved concurrently in such a way that the neighbouring two phases always maintained similar hardness. While the plastic deformation and grain refinement of ferrite occurred mainly via dislocation activities, the plastic deformation and grain refinement process of austenite were more complicated and included deformation twinning and de-twinning in coarse grains, grain refinement by twinning and dislocation–twin interactions, de-twinning in ultrafine grains and twin boundary subdivision.}, journal={ACTA MATERIALIA}, author={Cao, Y. and Wang, Y. B. and An, X. H. and Liao, X. Z. and Kawasaki, M. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2014}, month={Jan}, pages={16–29} }
 @article{cao_wang_chen_liao_kawasaki_ringer_langdon_zhu_2013, title={De-twinning via secondary twinning in face-centered cubic alloys}, volume={578}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2013.04.075}, abstractNote={We report a de-twinning process via secondary twinning in face-centred cubic structures with low stacking fault energies. A duplex stainless steel was deformed using high-pressure torsion. Primary twins with an average twin boundary (TB) spacing of ∼7 nm formed in the early stages of the deformation and this was followed by secondary twinning. The partial dislocations from the secondary twinning subsequently interacted with the primary TBs, leading to the de-twinning of the primary twins. As a result of the de-twinning process, the secondary twins with an average TB spacing of ∼1.7 nm reached a maximum length of ∼200 nm.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Cao, Y. and Wang, Y. B. and Chen, Z. B. and Liao, X. Z. and Kawasaki, M. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2013}, month={Aug}, pages={110–114} }
 @article{cheng_xu_jian_yuan_tsai_zhu_zhang_millett_2013, title={Dislocations with edge components in nanocrystalline bcc Mo}, volume={28}, DOI={10.1557/jmr.2012.403}, abstractNote={Abstract}, number={13}, journal={Journal of Materials Research}, author={Cheng, G. M. and Xu, W. Z. and Jian, W. W. and Yuan, H. and Tsai, M. H. and Zhu, Y.T. and Zhang, Y. F. and Millett, P. C.}, year={2013}, pages={1820–1826} }
 @article{zhu_jia_barsoum_mathaudhu_misra_nan_raabe_2013, title={Editorial}, volume={1}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2013.779091}, DOI={10.1080/21663831.2013.779091}, number={1}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Zhu, Yuntian T. and Jia, Quanxi and Barsoum, Michel W. and Mathaudhu, Suveen and Misra, Amit and Nan, Cenwen and Raabe, Dierk}, year={2013}, month={Mar}, pages={1–2} }
 @article{wang_liao_zhao_cooley_horita_zhu_2013, title={Elemental separation in nanocrystalline Cu-Al alloys}, volume={102}, DOI={10.1063/1.4811157}, abstractNote={Nanocrystallization by high-energy severe plastic deformation has been reported to increase the solubility of alloy systems and even to mix immiscible elements to form non-equilibrium solid solutions. In this letter, we report an opposite phenomenon—nanocrystallization of a Cu-Al single-phase solid solution by high-pressure torsion separated Al from the Cu matrix when the grain sizes are refined to tens of nanometers. The Al phase was found to form at the grain boundaries of nanocrystalline Cu. The level of the separation increases with decreasing grain size, which suggests that the elemental separation was caused by the grain size effect.}, number={23}, journal={Applied Physics Letters}, author={Wang, Y. B. and Liao, X. Z. and Zhao, Y. H. and Cooley, J. C. and Horita, Z. and Zhu, Y.T.}, year={2013} }
 @article{bufford_liu_zhu_bi_jia_wang_zhang_2013, title={Formation Mechanisms of High-density Growth Twins in Aluminum with High Stacking-Fault Energy}, volume={1}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2012.761654}, DOI={10.1080/21663831.2012.761654}, abstractNote={Nanotwins readily form in numerous face-centered-cubic (fcc) metals with low stacking-fault energy (SFE). However, growth twins rarely form in Al due to its high SFE, ∼120–165 mJ/m2. Here, using thin inter-layers or buffer layers of a low-SFE fcc metal (Ag), we overcome the SFE barrier and successfully grow high-density coherent and incoherent twin boundaries into Al. We identify three mechanisms that induce growth twins in Al and demonstrate enhanced mechanical strength in twinned Al. This study reveals an effective means that may be generalized to control growth twin formation in fcc metals with high SFE.}, number={1}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Bufford, D. and Liu, Y. and Zhu, Y. and Bi, Z. and Jia, Q.X. and Wang, H. and Zhang, X.}, year={2013}, month={Feb}, pages={51–60} }
 @article{zhu_liao_wu_narayan_2013, title={Grain size effect on deformation twinning and detwinning}, volume={48}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-013-7140-0}, abstractNote={This article systematically overviews the grain size effect on deformation twinning and detwinning in face-centered cubic (fcc) metals. With decreasing grain size, coarse-grained fcc metals become more difficult to deform by twinning, whereas nanocrystalline (nc) fcc metals first become easier to deform by twinning and then become more difficult, exhibiting an optimum grain size for twinning. The transition in twinning behavior from coarse-grained to nc fcc metals is caused by the change in deformation mechanisms. An analytical model based on observed deformation physics in nc metals, i.e., grain boundary emission of dislocations, provides an explanation of the observed optimum grain size for twinning in nc fcc metals. The detwinning process is caused by the interaction between dislocations and twin boundaries. Under a certain deformation condition, there exists a grain size range where the twinning process dominates over the detwinning process to produce the highest density of twins.}, number={13}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Zhu, Y. T. and Liao, X. Z. and Wu, X. L. and Narayan, J.}, year={2013}, month={Jul}, pages={4467–4475} }
 @article{wu_zhu_narayan_2013, title={Grain size effect on twin density in as-deposited nanocrystalline Cu film}, volume={93}, ISSN={1478-6435 1478-6443}, url={http://dx.doi.org/10.1080/14786435.2013.829251}, DOI={10.1080/14786435.2013.829251}, abstractNote={Here, we report the formation of twins and grain size dependence of twin density in nanocrystalline (NC) copper films fabricated by pulsed laser deposition. It is found that the percentage of grains containing twins decreases with decreasing grain size in the grain size range of 2–10 nm. Surprisingly, although the twins were formed during the deposition process without mechanical deformation, our analysis suggests that they are most likely deformation twins formed under high internal stress existing in the NC Cu films. This phenomenon may also happen in other NC metallic thin films where internal stresses are high.}, number={35}, journal={Philosophical Magazine}, publisher={Informa UK Limited}, author={Wu, F. and Zhu, Y.T. and Narayan, J.}, year={2013}, month={Dec}, pages={4355–4363} }
 @article{xu_zhang_cheng_jian_millett_koch_mathaudhu_zhu_2013, title={In-situ atomic-scale observation of irradiation-induced void formation}, volume={4}, ISSN={["2041-1723"]}, DOI={10.1038/ncomms3288}, abstractNote={The formation of voids in an irradiated material significantly degrades its physical and mechanical properties. Void nucleation and growth involve discrete atomic-scale processes that, unfortunately, are not yet well understood due to the lack of direct experimental examination. Here we report an in-situ atomic-scale observation of the nucleation and growth of voids in hexagonal close-packed magnesium under electron irradiation. The voids are found to first grow into a plate-like shape, followed by a gradual transition to a nearly equiaxial geometry. Using atomistic simulations, we show that the initial growth in length is controlled by slow nucleation kinetics of vacancy layers on basal facets and anisotropic vacancy diffusivity. The subsequent thickness growth is driven by thermodynamics to reduce surface energy. These experiments represent unprecedented resolution and characterization of void nucleation and growth under irradiation, and might help with understanding the irradiation damage of other hexagonal close-packed materials. The irradiation of crystalline materials is known to create various types of lattice defects, which can degrade mechanical performance. Here, Xu et al. observe the in-situnucleation and growth of atomic-scale voids in magnesium during electron irradiation.}, journal={NATURE COMMUNICATIONS}, author={Xu, Weizong and Zhang, Yongfeng and Cheng, Guangming and Jian, Weiwei and Millett, Paul C. and Koch, Carl C. and Mathaudhu, Suveen N. and Zhu, Yuntian}, year={2013}, month={Aug} }
 @article{wu_zhu_narayan_2014, title={Macroscopic Twinning Strain in Nanocrystalline Cu}, volume={2}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2013.862874}, DOI={10.1080/21663831.2013.862874}, abstractNote={Most deformation twins in nanocrystalline face-centered cubic (NC fcc) metals are reported to produce zero-macrostrain, which is attributed to either random activation of partials (RAP) or cooperative slip of three partials (CSTP). Here, we report that when the RAP mechanism is suppressed, ∼44% twins in NC Cu produced zero-macrostrain via the CSTP mechanism. This indicates that both RAP and CSTP are major mechanisms to generate zero-macrostrain twins. In addition, our results also indicate that stress state affects the twinning mechanism in NC fcc metals, and monotonic activation of partials with the same Burgers vector dominates twin formation under monotonic stress.}, number={2}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Wu, F. and Zhu, Y.T. and Narayan, J.}, year={2014}, pages={63–69} }
 @article{jiang_wang_zhu_hui_qiu_2014, title={Mechanical, electrical and thermal properties of aligned carbon nanotube/polyimide composites}, volume={56}, ISSN={["1879-1069"]}, DOI={10.1016/j.compositesb.2013.08.064}, abstractNote={Carbon nanotubes (CNTs) have high strength and modulus, large aspect ratio, and good electrical and thermal conductivities, which make them attractive for fabricating composite. The poly(biphenyl dianhydride-p-phenylenediamine) (BPDA/PDA) polyimide has good mechanical and thermal performances and is herein used as matrix in unidirectional carbon nanotube composites for the first time. The strength and modulus of the composite increase by 2.73 and 12 times over pure BPDA–PDA polyimide, while its electrical conductivity reaches to 183 S/cm, which is 1018 times over pure polyimide. The composite has excellent high temperature resistance, and its thermal conductivity is beyond what has been achieved in previous studies. The improved properties of the composites are due to the long CNT length, high level of CNT alignment, high CNT volume fraction and good CNT dispersion in polyimide matrix. The composite is promising for applications that require high strength, lightweight, or high electrical and thermal conductivities.}, journal={COMPOSITES PART B-ENGINEERING}, author={Jiang, Qian and Wang, Xin and Zhu, Yuntian and Hui, David and Qiu, Yiping}, year={2014}, month={Jan}, pages={408–412} }
 @article{yuan_ma_jiang_lu_jian_song_zhu_2013, title={Optimizing the strength and ductility of AZ91 Mg alloy by ECAP and subsequent aging}, volume={588}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2013.09.052}, abstractNote={We report an effective approach to achieve an excellent combination of high strength and good ductility in the AZ91 Mg alloy. The approach involves solution heat treatment, equal channel angular pressing (ECAP) and subsequent aging. This approach is effective in accumulating dislocations and promoting the formation of large spherical precipitates during ECAP. The aging produced much finer precipitates with uniform distribution inside the grains. The hierarchical precipitate structure produced by the current approach rendered high strength and good ductility.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Yuan, Yuchun and Ma, Aibin and Jiang, Jinghua and Lu, Fumin and Jian, Weiwei and Song, Dan and Zhu, Yuntian T.}, year={2013}, month={Dec}, pages={329–334} }
 @article{jian_cheng_xu_koch_wang_zhu_mathaudhu_2013, title={Physics and model of strengthening by parallel stacking faults}, volume={103}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.4822323}, DOI={10.1063/1.4822323}, abstractNote={We have recently reported that parallel stacking faults (SFs) can tremendously increase the strength of a magnesium alloy. The strengthening is found to increase linearly with the reciprocal of the mean SF spacing, d. In this study we analyze dislocation interactions with SFs, and then propose a physics-based model to explain the observed relationship between yield strength and SFs spacing. Similar to the empirical Hall-Petch relationship for grain size, it is expected that this strengthening mechanism will hold true for a variety of materials engineered with parallel spaced stacking faults over a wide range of fault spacing.}, number={13}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Jian, W. W. and Cheng, G. M. and Xu, W. Z. and Koch, C. C. and Wang, Q. D. and Zhu, Y. T. and Mathaudhu, S. N.}, year={2013}, month={Sep}, pages={133108} }
 @article{zhu_2013, title={Preface}, volume={48}, ISSN={0022-2461 1573-4803}, url={http://dx.doi.org/10.1007/S10853-013-7324-7}, DOI={10.1007/S10853-013-7324-7}, number={13}, journal={Journal of Materials Science}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian}, year={2013}, month={Mar}, pages={4459–4460} }
 @article{zhu_2013, title={Special issue: Nanostructured materials preface}, volume={48}, number={13}, journal={Journal of Materials Science}, author={Zhu, Y. T.}, year={2013}, pages={4459–4460} }
 @article{thiagarajan_wang_bradford_zhu_yuan_2014, title={Stabilizing carbon nanotube yarns using chemical vapor infiltration}, volume={90}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2013.10.008}, abstractNote={Carbon nanotube (CNT) yarns exhibit high strength, low density, and relatively good conductivity and piezoresistivity, which makes them an ideal candidate for many advanced applications such as reinforcements for multifunctional composites. However, CNT yarns usually lack the required property stability under load. In this paper a method for stabilizing CNT yarn using chemical vapor infiltration (CVI) to infiltrate and deposit pyrocarbon into CNT yarns is reported. The deposited pyrocarbon effectively binds neighboring CNTs to inhibit inter-nanotube sliding under load, which consequently stabilize the CNT yarns. Relaxation tests showed that compared to pristine CNT yarns, the stabilized yarns have higher electrical stability as well as load retention (∼93% versus ∼61%). There was also a concomitant increase in density along with improved electrical conductivity, mechanical strength and stiffness. Furthermore, under sonication the CVI treated yarns resisted disintegration, making them suitable for electrochemical applications.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Thiagarajan, V. and Wang, X. and Bradford, P. D. and Zhu, Y. T. and Yuan, F. G.}, year={2014}, month={Jan}, pages={82–87} }
 @article{xiao_li_zhu_zhao_chen_zhu_2013, title={Surface characterization and corrosion behavior of a novel gold-imitation copper alloy with high tarnish resistance in salt spray environment}, volume={76}, ISSN={0010-938X}, url={http://dx.doi.org/10.1016/J.CORSCI.2013.05.026}, DOI={10.1016/J.CORSCI.2013.05.026}, abstractNote={A novel gold-imitation copper alloy (CuZnAlNiSnBRe) was designed and its corrosion behavior in salt spray environment was investigated. The new alloy has better tarnish resistance and corrosion resistance than the current coinage alloy used in China (H7211). A multi-layer film formed on the surface of the new alloy after a period of exposure to salt spray was responsible for the good resistance of the alloy. The corrosion products were a mixture of CuO, Cu2O, ZnO, Al2O3 and Al(OH)3, with the transition from Cu2O to CuO occurring during the corrosion process.}, journal={Corrosion Science}, publisher={Elsevier BV}, author={Xiao, Zhu and Li, Zhou and Zhu, Anyin and Zhao, Yuyuan and Chen, Jinglin and Zhu, Yuntian}, year={2013}, month={Nov}, pages={42–51} }
 @article{wu_wen_lavernia_narayan_zhu_2013, title={Twin intersection mechanisms in nanocrystalline fcc metals}, volume={585}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2013.07.063}, abstractNote={Deformation twins have been reported to produce high strength and ductility. Intersections of deformation twins may affect the microstructural evolution during plastic deformation and consequently influence mechanical properties. However, the mechanisms governing twin-intersection behavior remain poorly understood. In this study, we investigated twin intersection mechanisms by observing twin transmission across the boundary of another twin using high-resolution transmission electron microscopy. Based on the experimental observations, mechanisms were proposed for twin–twin intersections and associated dislocation reactions in nanocrystalline fcc materials.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Wu, F. and Wen, H. M. and Lavernia, E. J. and Narayan, J. and Zhu, Y. T.}, year={2013}, month={Nov}, pages={292–296} }
 @article{zheng_li_xu_zhou_mathaudhu_zhu_lavernia_2013, title={Twinning in cryomilled nanocrystalline Mg powder}, volume={93}, ISSN={["1362-3036"]}, DOI={10.1080/09500839.2013.801567}, abstractNote={Nanocrystalline (nc) Mg powder was synthesized via cryomilling. Extension twins were identified with high-resolution transmission electron microscopy in the cryomilled powders and the study presents the first evidence of twinning in unalloyed nc Mg. The formation of twins in the nc Mg is attributed to a high strain rate, the low (cryogenic) temperature and high local shear stresses present around the grain boundaries during deformation by cryomilling.}, number={8}, journal={PHILOSOPHICAL MAGAZINE LETTERS}, author={Zheng, Baolong and Li, Ying and Xu, Weizong and Zhou, Yizhang and Mathaudhu, Suveen N. and Zhu, Yuntian and Lavernia, Enrique J.}, year={2013}, month={Aug}, pages={457–464} }
 @article{an_song_huang_liao_ringer_langdon_zhu_2014, title={Twinning via the motion of incoherent twin boundaries nucleated at grain boundaries in a nanocrystalline Cu alloy}, volume={72-73}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2013.10.014}, abstractNote={We report the formation of deformation twins in a nanocrystalline Cu–25 at.% Ni alloy with medium stacking fault energy via the propagation of Σ3{1 1 2} incoherent twin boundaries (ITBs) that are nucleated from grain boundaries. This deformation twinning process does not generate net macroscopic strain since the Burgers vectors of the three partial dislocations on three successive {1 1 1} planes comprising an ITB sum to zero. The moving direction of ITBs determines the occurrence of twinning or detwinning in nanocrystalline materials.}, journal={SCRIPTA MATERIALIA}, author={An, X. H. and Song, M. and Huang, Y. and Liao, X. Z. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2014}, month={Feb}, pages={35–38} }
 @article{jian_cheng_xu_yuan_tsai_wang_koch_zhu_mathaudhu_2013, title={Ultrastrong Mg Alloy via Nano-spaced Stacking Faults}, volume={1}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2013.765927}, DOI={10.1080/21663831.2013.765927}, abstractNote={Mg alloys are among the lightest alloys but they are usually weak. Here we report a new mechanism to make them ultrastrong while maintaining good ductility. Stacking faults with nanoscale spacing were introduced into a Mg–8.5Gd–2.3Y–1.8Ag–0.4Zr (wt%) alloy by conventional hot rolling, which produced a yield strength of ∼575 MPa, an ultimate strength of ∼600 MPa, and a uniform elongation of ∼5.2 %. Low stacking fault (SF) energy enabled the introduction of a high density of SFs, which impeded dislocation slip and promoted dislocation accumulation. These findings provide guidance for developing Mg alloys with superior mechanical properties.}, number={2}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Jian, W. W. and Cheng, G. M. and Xu, W. Z. and Yuan, H. and Tsai, M. H. and Wang, Q. D. and Koch, C. C. and Zhu, Y. T. and Mathaudhu, S. N.}, year={2013}, month={Mar}, pages={61–66} }
 @article{zhang_ronning_gofryk_mara_haberkorn_zou_wang_lee_bauer_mccleskey_et al._2012, title={Aligned carbon nanotubes sandwiched in epitaxial NbC film for enhanced superconductivity}, volume={4}, DOI={10.1039/c2nr11906d}, abstractNote={Highly aligned carbon nanotube (CNT) ribbons were sandwiched in epitaxial superconducting NbC films by a chemical solution deposition method. The incorporation of aligned long CNTs into NbC film enhances the normal-state conductivity and improves the superconducting properties of the assembly.}, number={7}, journal={Nanoscale}, author={Zhang, Yingying and Ronning, Filip and Gofryk, Krzysztof and Mara, Nathan. A. and Haberkorn, Nestor and Zou, Guifu and Wang, Haiyan and Lee, Joon H. and Bauer, Eve and McCleskey, Thomas M. and et al.}, year={2012}, pages={2268–2271} }
 @article{cao_wang_liao_kawasaki_ringer_langdon_zhu_2012, title={Applied stress controls the production of nano-twins in coarse-grained metals}, volume={101}, DOI={10.1063/1.4769216}, abstractNote={We present evidence that the level of the applied stress plays a critical role in deformation twinning in face-centred cubic alloys. While conventional cold rolling of a face-centred cubic structure produces a microstructure with a high-density of extended dislocations, increasing the applied stress using high-pressure torsion gives a nano-twinned coarse-grained structure. This suggests the existence of a critical stress for deformation twinning which thereby delineates an approach for the production of nano-twinned microstructures in coarse-grained materials with superior mechanical properties.}, number={23}, journal={Applied Physics Letters}, author={Cao, Y. and Wang, Y. B. and Liao, X. Z. and Kawasaki, M. and Ringer, S. P. and Langdon, T. G. and Zhu, Y.T.}, year={2012} }
 @article{zu_lu_li_zhu_wang_chou_2012, title={Characterization of Carbon Nanotube Fiber Compressive Properties Using Tensile Recoil Measurement}, volume={6}, ISSN={["1936-0851"]}, DOI={10.1021/nn300857d}, abstractNote={The tensile properties of carbon nanotube (CNT) fibers have been widely studied. However, the knowledge of their compressive properties is still lacking. In this work, the compressive properties of both pure CNT fibers and epoxy infiltrated CNT fibers were studied using the tensile recoil measurement. The compressive strengths were obtained as 416 and 573 MPa for pure CNT fibers and CNT-epoxy composite fibers, respectively. In addition, microscopic analysis of the fiber surface morphologies revealed that the principal recoil compressive failure mode of pure CNT fiber was kinking, while the CNT-epoxy composite fibers exhibited a failure mode in bending with combined tensile and compressive failure morphologies. The effect of resin infiltration on CNT fiber compressive properties, including the compressive strength and the deformation mode, is discussed. This work expands the knowledge base of the overall mechanical properties of CNT fibers, which are essential for their application in multifunctional composites.}, number={5}, journal={ACS NANO}, author={Zu, Mei and Lu, Weibang and Li, Qing-Wen and Zhu, Yuntian and Wang, Guojian and Chou, Tsu-Wei}, year={2012}, month={May}, pages={4288–4297} }
 @article{li_fu_zhao_zhu_2012, title={Characterization of carbonic anhydrase II from Chlorella vulgaris in bio-CO2 capture}, volume={19}, ISSN={["0944-1344"]}, DOI={10.1007/s11356-012-1077-8}, abstractNote={Carbonic anhydrase II (CA II) can catalyze the reversible hydration reaction of CO(2) at a maximum of 1.4 × 10(6) molecules of CO(2) per second. The crude intracellular enzyme extract containing CA II was derived from Chlorella vulgaris. A successful CO(2) capture experiment with the presence of calcium had been conducted on the premise that the temperature was conditioned at a scope of 30-40 °C, that the biocatalyst-nurtured algal growth period lasted 3 days, and that pH ranged from7.5 to 8.5. Ions of K(+), Na(+), Ca(2+), Co(2+), Cu(2+), Fe(3+), Mg(2+), Mn(2+), and Zn(2+) at 0.01, 0.1, and 0.5 M were found to exhibit no more than 30 % inhibition on the residual activity of the biocatalyst. It is reasonable to expect that calcification catalyzed by microalgae presents an alternative to geological carbon capture and sequestration through a chain of fundamental researches carried on under the guidance of sequestration technology.}, number={9}, journal={ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH}, author={Li, Li and Fu, Ming-lai and Zhao, Yong-hao and Zhu, Yun-tian}, year={2012}, month={Nov}, pages={4227–4232} }
 @article{cheng_yuan_jian_xu_millett_zhu_2013, title={Deformation-induced omega phase in nanocrystalline Mo}, volume={68}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2012.09.033}, abstractNote={A deformation-induced hexagonal ω phase was first observed in pure nanocrystalline body-centered cubic (bcc) Mo using high-resolution transmission electron microscopy. As the grains were refined into nanometer sizes by deformation using high-pressure torsion under a pressure of ∼4 GPa at room temperature, the ω phase formed at the grain boundaries of bcc Mo with a crystallographic relationship close to the {1 1 2}〈1 1 1〉 twin orientation. Its formation was mainly attributed to the shear deformation on {1 1 2} planes in bcc Mo.}, number={2}, journal={SCRIPTA MATERIALIA}, author={Cheng, G. M. and Yuan, H. and Jian, W. W. and Xu, W. Z. and Millett, P. C. and Zhu, Y. T.}, year={2013}, month={Jan}, pages={130–133} }
 @article{wang_jiang_xu_cai_inoue_zhu_2013, title={Effect of carbon nanotube length on thermal, electrical and mechanical properties of CNT/bismaleimide composites}, volume={53}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2012.10.041}, abstractNote={Multi-wall carbon nanotubes (MWCNTs) with lengths of 0.65–1.3 mm were used to fabricate aligned and continuous MWCNT/bismaleimide composites. We found that longer CNTs resulted in higher thermal and electrical conductivities of the composites. The tensile strength and Young’s modulus, however, exhibited no CNT length dependency. Investigation of the CNT morphology by transmission electron microscopy revealed that the average nanotube diameter and wall number also increased with the CNT length, while the aspect ratio remained nearly unchanged. The structural changes significantly affected the phonon and electron transport in the composite structure, but the interplay of increased CNT length and diameter led to no appreciable change in the mechanical properties of the composites.}, journal={CARBON}, author={Wang, Xin and Jiang, Qian and Xu, Weizong and Cai, Wei and Inoue, Yoku and Zhu, Yuntian}, year={2013}, month={Mar}, pages={145–152} }
 @article{li_qian_zhao_zhu_2013, title={Enzyme kinetic characterization of microbe-produced urease for microbe-driven calcite mineralization}, volume={108}, ISSN={["1878-5204"]}, DOI={10.1007/s11144-012-0487-4}, number={1}, journal={REACTION KINETICS MECHANISMS AND CATALYSIS}, author={Li, Li and Qian, Chun-xiang and Zhao, Yong-hao and Zhu, Yun-tian}, year={2013}, month={Feb}, pages={51–57} }
 @article{cheng_jian_xu_yuan_millett_zhu_2013, title={Grain Size Effect on Deformation Mechanisms of Nanocrystalline bcc Metals}, volume={1}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2012.739580}, DOI={10.1080/21663831.2012.739580}, abstractNote={Nanocrystalline (NC) body-centered cubic (bcc) metals behave very differently from how NC metals with other crystal structures behave. Their strain rate sensitivity decreases with decreasing grain size, which is an observation that has not been well understood. Here, we report a significant effect of grain size on the deformation mechanism of NC bcc Mo. With decreasing grain size, the density of mixed and edge dislocations increases, while the density of screw dislocations decreases. When the grains become very small, the overall dislocation density decreases with decreasing grain size. These observations provide a logical explanation for the observed effect of grain size on strain rate sensitivity.}, number={1}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Cheng, G.M. and Jian, W.W. and Xu, W.Z. and Yuan, H. and Millett, P.C. and Zhu, Y.T.}, year={2013}, pages={26–31} }
 @article{tsai_yuan_cheng_xu_tsai_tsai_jian_juan_shen_chuang_et al._2013, title={Morphology, structure and composition of precipitates in Al0.3CoCrCu0.5FeNi high-entropy alloy}, volume={32}, ISSN={["1879-0216"]}, DOI={10.1016/j.intermet.2012.07.036}, abstractNote={High-entropy alloy is a new class of metallic materials with great potential for many applications. However, their microstructural characteristics, particularly those of precipitates, remain poorly understood. This has hindered the establishment of structure-property relationship in these alloys. Here, we report the morphology, crystal structure and composition of the precipitates in the Al0.3CoCrCu0.5FeNi high-entropy alloy. Two types of precipitates were identified, namely the plate-like and the spherical precipitates. Their formation sequence and mechanism during the cooling process are discussed based on thermodynamics.}, journal={INTERMETALLICS}, author={Tsai, Ming-Hung and Yuan, Hao and Cheng, Guangming and Xu, Weizong and Tsai, Kun-Yo and Tsai, Che-Wei and Jian, Weiwei W. and Juan, Chien-Chang and Shen, Wan-Jui and Chuang, Ming-Hao and et al.}, year={2013}, month={Jan}, pages={329–336} }
 @article{liu_zhao_inoue_wang_bradford_kim_qiu_zhu_2012, title={Poly(vinyl alcohol) reinforced with large-diameter carbon nanotubes via spray winding}, volume={43}, ISSN={["1878-5840"]}, DOI={10.1016/j.compositesa.2011.12.029}, abstractNote={For practical application of carbon nanotube (CNT)/polymer composites, it is critical to produce the composites at high speed and large scale. In this study, multi-walled carbon nanotubes (MWNTs) with large diameter (∼45 nm) and polyvinyl alcohol (PVA) were used to increase the processing speed of a recently developed spraying winding technique. The effect of the different winding speed and sprayed solution concentration to the performance of the composite films were investigated. The CNT/PVA composites exhibit tensile strength of up to 1 GPa, and modulus of up to 70 GPa, with a CNT weight fraction of 53%. In addition, an electrical conductivity of 747 S/cm was obtained for the CNT/PVA composites. The good mechanical and electrical properties are attributed to the uniform CNTs and PVA matrix integration and the high degree of tube alignment.}, number={4}, journal={COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING}, author={Liu, Wei and Zhao, Haibo and Inoue, Yoku and Wang, Xin and Bradford, Philip D. and Kim, Hyungsup and Qiu, Yiping and Zhu, Yuntian}, year={2012}, month={Apr}, pages={587–592} }
 @article{mathaudhu_huang_kim_langdon_lowe_valiev_wu_zehetbauer_zhu_2012, title={Preface to the special issue on ultrafine-grained materials}, volume={47}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-012-6735-1}, number={22}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Mathaudhu, Suveen N. and Huang, Xiaoxu and Kim, Hyoung Seop and Langdon, Terence G. and Lowe, Terry C. and Valiev, Ruslan Z. and Wu, Xiaolei and Zehetbauer, Michael and Zhu, Yuntian T.}, year={2012}, month={Nov}, pages={7717–7718} }
 @article{tsai_yuan_cheng_xu_jian_chuang_juan_yeh_lin_zhu_et al._2013, title={Significant hardening due to the formation of a sigma phase matrix in a high entropy alloy}, volume={33}, ISSN={["1879-0216"]}, DOI={10.1016/j.intermet.2012.09.022}, abstractNote={The hardening in Al0.3CrFe1.5MnNi0.5 high-entropy alloy not only nearly triples the hardness of the alloy, but also shows a quick hardening response and the absence of overaging. However, the crystal structure, morphology, and composition of the hardening phase have not yet been confirmed. Here, such information regarding the hardening phase is investigated. It was found that the hardening phase is a Cr–Mn–Fe ternary sigma phase. Unlike in conventional engineering alloys, the sigma phase is not precipitated from the matrix, instead, the whole BCC matrix transforms to sigma phase almost without changing its composition. Therefore, the hardening phenomenon is not a precipitation hardening reaction as suggested before.}, journal={INTERMETALLICS}, author={Tsai, Ming-Hung and Yuan, Hao and Cheng, Guangming and Xu, Weizong and Jian, Weiwei W. and Chuang, Ming-Hao and Juan, Chien-Chang and Yeh, An-Chou and Lin, Su-Jien and Zhu, Yuntian and et al.}, year={2013}, month={Feb}, pages={81–86} }
 @article{zu_li_zhu_zhu_wang_byun_chou_2013, title={Stress relaxation in carbon nanotube-based fibers for load-bearing applications}, volume={52}, ISSN={["0008-6223"]}, url={http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=ORCID&SrcApp=OrcidOrg&DestLinkType=FullRecord&DestApp=WOS_CPL&KeyUT=WOS:000314192700038&KeyUID=WOS:000314192700038}, DOI={10.1016/j.carbon.2012.09.036}, abstractNote={Carbon nanotube (CNT) based continuous fiber, a CNT assembly that could retain the superb properties of individual CNTs on a macroscopic scale, has emerged as a promising candidate for reinforcement in multifunctional composites. While existing research has extensively examined their short-term mechanical properties based upon quasi-static measurements, the long-term durability of CNT fibers has been largely neglected. Here we report time-dependent behavior of CNT fibers, with a particular focus on tensile stress relaxation. Both the pure CNT fiber and the CNT/epoxy composite fiber exhibited significant stress decay during the relaxation process, and this time-dependent behavior became more significant at a higher initial strain level, a lower strain rate and a greater gauge length. The present approach signifies a fundamental difference in the load-bearing characteristics between CNT fibers and traditional advanced fibers, which has major implications for the long-term durability of CNT fibers in load-bearing multifunctional applications.}, journal={CARBON}, author={Zu, Mei and Li, Qingwen and Zhu, Yuntian and Zhu, Yong and Wang, Guojian and Byun, Joon-Hyung and Chou, Tsu-Wei}, year={2013}, month={Feb}, pages={347–355} }
 @article{ni_wang_liao_figueiredo_li_ringer_langdon_zhu_2012, title={The effect of dislocation density on the interactions between dislocations and twin boundaries in nanocrystalline materials}, volume={60}, ISSN={["1359-6454"]}, DOI={10.1016/j.actamat.2012.02.026}, abstractNote={The interactions between dislocations and twin boundaries (TBs) are significantly affected by both intrinsic material properties and extrinsic factors, including stacking fault energy, the energy barriers for dislocation reactions at TBs, twin thickness and applied stress. In this study, dislocation–TB interactions in grains with different dislocation densities were investigated and we conclude that the dislocation density also affects the dislocation–TB interactions. In a twinned grain with a low dislocation density, a dislocation may react with a TB to fully or partially penetrate the TB or to be absorbed by the TB via different dislocation reactions. Alternatively, in a twinned grain with a high dislocation density, dislocations tangle with each other and are pinned at the TBs, thereby making it unfavourable for further dislocation reactions to mediate dislocation penetration across the TB. This leads to an accumulation of dislocations at the TBs, raising the local strain energy, which, in turn, is released by the activation of secondary twins by partial dislocation emissions from the other side of the TB.}, number={6-7}, journal={ACTA MATERIALIA}, author={Ni, S. and Wang, Y. B. and Liao, X. Z. and Figueiredo, R. B. and Li, H. Q. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2012}, month={Apr}, pages={3181–3189} }
 @article{hodge_furnish_shute_liao_huang_hong_zhu_barbee_weertman_2012, title={Twin stability in highly nanotwinned Cu under compression, torsion and tension}, volume={66}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2012.01.027}, abstractNote={Twin stability under four distinct mechanical loading states has been investigated for highly nanotwinned Cu containing parallel nanotwins ∼40 nm thick. Observed deformation-induced microstructural changes under tension, compression, tension–tension fatigue and torsion are qualitatively compared in order to assess twin stability as a function of the loading direction and stress. It is observed that the twins are very stable although small microstructural changes vary with deformation mode. Shear bands, deformation-induced grain growth and detwinning are also discussed.}, number={11}, journal={SCRIPTA MATERIALIA}, author={Hodge, A. M. and Furnish, T. A. and Shute, C. J. and Liao, Y. and Huang, X. and Hong, C. S. and Zhu, Y. T. and Barbee, T. W., Jr. and Weertman, J. R.}, year={2012}, month={Jun}, pages={872–877} }
 @article{di_hu_chen_yong_chen_feng_zhu_li_2012, title={Ultrastrong, Foldable, and Highly Conductive Carbon Nanotube Film}, volume={6}, ISSN={["1936-0851"]}, DOI={10.1021/nn301321j}, abstractNote={Preparation of strong, flexible, and multifunctional carbon-based films has attracted considerable interest not only in fundamental research areas but also for industrial applications. We report a binder-free, ultrastrong, and foldable carbon nanotube (CNT) film using aligned few-walled nanotube sheets drawn from spinnable nanotube arrays. The film exhibits tensile strengths up to ∼2 GPa and a Young's modulus up to ∼90 GPa, which is markedly superior to other types of carbon-based films reported, including commercial graphite foils, buckypapers, and graphene-related papers. The film can bear severe bending (even being folded) and shows good structure integrity and negligible change in electric conductivity. The unique structure of the CNT film (good nanotube alignment, high packing density) provides the film with direct and efficient transport paths for electricity. As a flexible charge collector, it favors a magnesium oxide coating to exhibit high charge/discharge rate stability and an excellent electrochemical capacitance close to its theoretical value.}, number={6}, journal={ACS NANO}, author={Di, Jiangtao and Hu, Dongmei and Chen, Hongyuan and Yong, Zhenzhong and Chen, Minghai and Feng, Zhihai and Zhu, Yuntian and Li, Qingwen}, year={2012}, month={Jun}, pages={5457–5464} }
 @article{wang_yong_li_bradford_liu_tucker_cai_wang_yuan_zhu_2013, title={Ultrastrong, Stiff and Multifunctional Carbon Nanotube Composites}, volume={1}, ISSN={2166-3831}, url={http://dx.doi.org/10.1080/21663831.2012.686586}, DOI={10.1080/21663831.2012.686586}, abstractNote={Carbon nanotubes (CNTs) are an order of magnitude stronger than any other current engineering fiber. However, for the past two decades, it has been a challenge to utilize their reinforcement potential in composites. Here, we report CNT composites with unprecedented multifunctionalities, including record high strength (3.8 GPa), high Young's modulus (293 GPa), electrical conductivity (1230 S·cm −1), and thermal conductivity (41 W m −1 K −1). These superior properties are derived from the long length, high volume fraction, good alignment and reduced waviness of the CNTs, which were produced by a novel-processing approach that can be easily scaled up for industrial production.}, number={1}, journal={Materials Research Letters}, publisher={Informa UK Limited}, author={Wang, X. and Yong, Z.Z. and Li, Q.W. and Bradford, P.D. and Liu, W. and Tucker, D.S. and Cai, W. and Wang, H. and Yuan, F.G. and Zhu, Y.T.}, year={2013}, pages={19–25} }
 @article{xu_wang_zhu_zhu_2012, title={Wavy Ribbons of Carbon Nanotubes for Stretchable Conductors}, volume={22}, ISSN={["1616-3028"]}, DOI={10.1002/adfm.201102032}, abstractNote={AbstractWavy ribbons of carbon nanotubes (CNTs) are embedded in elastomeric substrates to fabricate stretchable conductors that exhibit excellent performance in terms of high stretchability and small resistance change. A CNT ribbon with a thin layer of sputtered Au/Pd film is transferred onto a prestrained poly(dimethylsiloxane) (PDMS) substrate and buckled out‐of‐plane upon release of the prestrain. Embedded in PDMS, the wavy CNT ribbon is able to accommodate large stretching (up to the prestrain) with little change in resistance. For a prestrain of 100%, the resistance increases only about 4.1% when the wavy CNT ribbon is stretched to the prestrain. A simple stretchable circuit consisting of a light‐emitting diode and two wavy ribbons is demonstrated and shows constant response on significant twisting, folding, or stretching. Fabricated with a simple buckling approach, the wavy CNT‐ribbon‐based stretchable conductors (e.g., interconnects and electrodes) could play an important role in stretchable electronics, sensors, photovoltaics, and energy storage.}, number={6}, journal={ADVANCED FUNCTIONAL MATERIALS}, author={Xu, Feng and Wang, Xin and Zhu, Yuntian and Zhu, Yong}, year={2012}, month={Mar}, pages={1279–1283} }
 @article{han_su_jin_zhu_2011, title={Basal-plane stacking-fault energies of Mg: A first-principles study of Li- and Al-alloying effects}, volume={64}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2010.11.034}, abstractNote={Alloying effects due to Li and Al were examined in terms of generalized stacking-fault energies (GSFEs) associated with basal planes of hexagonal close-packed Mg. The GSFE profiles were obtained using a first-principles technique in combination with climbing-image nudged elastic band methods. Our results show that Li alloying can facilitate dislocation-mediated processes while sequential faulting across basal planes becomes favorable with Al alloying. Such a difference is attributed to the fact that the two alloying elements tend to form different types of bond critical points in Mg.}, number={8}, journal={SCRIPTA MATERIALIA}, author={Han, J. and Su, X. M. and Jin, Z. -H. and Zhu, Y. T.}, year={2011}, month={Apr}, pages={693–696} }
 @article{meng_zhang_xu_yong_chen_chen_li_zhu_2011, title={Carbon Nanotube Composite Films with Switchable Transparency}, volume={3}, ISSN={["1944-8252"]}, DOI={10.1021/am200114r}, abstractNote={A composite film with switchable transparency is fabricated by sandwiching a carbon nanotube (CNT) sheet within polyurethane (PU) films. The introduction of CNTs not only makes the composite film electrically conductive but also induces a rapid crystal melting of soft segments in the PU. As a result, the film can be switched from opaque to transparent in just several seconds after turning on voltage, and reversed back to opaque after turning off voltage. The film also possesses several other attractive properties, including excellent flexibility, low energy consumption, switching speed insensitivity to ambient temperature, and easy coloration, which make the film promising for a wide variety of practical applications.}, number={3}, journal={ACS APPLIED MATERIALS & INTERFACES}, author={Meng, Fancheng and Zhang, Xiaohua and Xu, Geng and Yong, Zhenzhong and Chen, Hongyuan and Chen, Minghai and Li, Qingwen and Zhu, Yuntian}, year={2011}, month={Mar}, pages={658–661} }
 @article{wang_krommenhoek_bradford_gong_tracy_parsons_luo_zhu_2011, title={Coating Alumina on Catalytic Iron Oxide Nanoparticles for Synthesizing Vertically Aligned Carbon Nanotube Arrays}, volume={3}, ISSN={1944-8244 1944-8252}, url={http://dx.doi.org/10.1021/am201082m}, DOI={10.1021/am201082m}, abstractNote={To synthesize long and uniform vertically aligned carbon nanotube (VACNT) arrays, it is essential to use catalytic nanoparticles (NPs) with monodisperse sizes and to avoid NP agglomeration at the growth temperature. In this work, VACNT arrays were grown on chemically synthesized Fe(3)O(4) NPs of diameter 6 nm by chemical vapor deposition. Coating the NPs with a thin layer of Al(2)O(3) prior to CNT growth preserves the monodisperse sizes, resulting in uniform, thick and dense VACNT arrays. Comparison with uncoated NPs shows that the Al(2)O(3) coating effectively prevents the catalyst NPs from sintering and coalescing, resulting in improved control over VACNT growth.}, number={11}, journal={ACS Applied Materials & Interfaces}, publisher={American Chemical Society (ACS)}, author={Wang, Xin and Krommenhoek, Peter J. and Bradford, Philip D. and Gong, Bo and Tracy, Joseph B. and Parsons, Gregory N. and Luo, Tzy-Jiun M. and Zhu, Yuntian T.}, year={2011}, month={Oct}, pages={4180–4184} }
 @misc{zhu_liao_wu_2012, title={Deformation twinning in nanocrystalline materials}, volume={57}, ISSN={["1873-2208"]}, DOI={10.1016/j.pmatsci.2011.05.001}, abstractNote={Nanocrystalline (nc) materials can be defined as solids with grain sizes in the range of 1–100 nm. Contrary to coarse-grained metals, which become more difficult to twin with decreasing grain size, nanocrystalline face-centered-cubic (fcc) metals become easier to twin with decreasing grain size, reaching a maximum twinning probability, and then become more difficult to twin when the grain size decreases further, i.e. exhibiting an inverse grain-size effect on twinning. Molecular dynamics simulations and experimental observations have revealed that the mechanisms of deformation twinning in nanocrystalline metals are different from those in their coarse-grained counterparts. Consequently, there are several types of deformation twins that are observed in nanocrystalline materials, but not in coarse-grained metals. It has also been reported that deformation twinning can be utilized to enhance the strength and ductility of nanocrystalline materials. This paper reviews all aspects of deformation twinning in nanocrystalline metals, including deformation twins observed by molecular dynamics simulations and experiments, twinning mechanisms, factors affecting the twinning, analytical models on the nucleation and growth of deformation twins, interactions between twins and dislocations, and the effects of twins on mechanical and other properties. It is the authors' intention for this review paper to serve not only as a valuable reference for researchers in the field of nanocrystalline metals and alloys, but also as a textbook for the education of graduate students.}, number={1}, journal={PROGRESS IN MATERIALS SCIENCE}, author={Zhu, Y. T. and Liao, X. Z. and Wu, X. L.}, year={2012}, month={Jan}, pages={1–62} }
 @article{ni_wang_liao_li_figueiredo_ringer_langdon_zhu_2011, title={Effect of grain size on the competition between twinning and detwinning in nanocrystalline metals}, volume={84}, DOI={10.1103/PhysRevB.84.235401}, abstractNote={Both twinning and detwinning have been reported to occur during the deformation of nanocrystalline (nc) face-centered-cubic metals. This raises the issue of how these two processes compete with each other. Here, we report that the twinning process dominates in a certain range of grain sizes, whereas, the detwinning process dominates outside of this range to annihilate all twins. These experimental observations establish a full spectrum of grain-size effects on deformation twinning and detwinning and are explained by the deformation physics. They also provide a fundamental basis for understanding and designing the mechanical behavior of nc metals and alloys}, number={23}, journal={Physical Review B}, author={Ni, S. and Wang, Y. B. and Liao, X. Z. and Li, H. Q. and Figueiredo, R. B. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2011} }
 @article{ni_sha_wang_liao_alhajeri_li_zhu_langdon_ringer_2011, title={Elemental redistribution in a nanocrystalline Ni-Fe alloy induced by high-pressure torsion}, volume={528}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2011.06.057}, abstractNote={An electrochemically deposited nanocrystalline supersaturated face-centred-cubic Ni–21 at.% Fe alloy with an initial average grain size of ∼21 nm was processed using high-pressure torsion (HPT) that resulted in grain growth via grain rotation and coalescence to an average grain size of ∼53 nm. Atom probe tomography investigations revealed that the supersaturated Ni–Fe solid solution was stable under HPT and that C and S atoms, which are the major impurities in the material and segregated to the grain boundaries (GBs) of the as-deposited material, migrated from disappearing GBs to the remaining GBs during HPT. We propose that the elemental redistribution was facilitated by GB diffusion and the motion of a large volume of HPT-induced defects at the GB regions during the grain growth process. This elemental redistribution process is different from other HPT-induced elemental redistribution processes reported in the literature.}, number={25-26}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Ni, S. and Sha, G. and Wang, Y. B. and Liao, X. Z. and Alhajeri, S. N. and Li, H. Q. and Zhu, Y. T. and Langdon, T. G. and Ringer, S. P.}, year={2011}, month={Sep}, pages={7500–7505} }
 @article{youssef_wang_liao_mathaudhu_kecskes_zhu_koch_2011, title={High hardness in a nanocrystalline Mg97Y2Zn1 alloy}, volume={528}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2011.06.017}, abstractNote={A nanocrystalline Mg97Y2Zn1 alloy was prepared with an average grain size of 21 nm by mechanical alloying of elemental powders. The structure of the alloy was characterized by X-ray diffraction and transmission electron microscopy. The hardness of the alloy as-milled for 8 h at room temperature was 2.1 GPa. After compaction and annealing at 573 K, the average grain size slightly increases to 28 nm with an increase in hardness to 2.4 GPa. These are the highest values for hardness yet reported for a crystalline Mg-based (>95% Mg) alloy. Possible factors leading to this high strength are discussed.}, number={25-26}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Youssef, K. M. and Wang, Y. B. and Liao, X. Z. and Mathaudhu, S. N. and Kecskes, L. J. and Zhu, Y. T. and Koch, C. C.}, year={2011}, month={Sep}, pages={7494–7499} }
 @article{shute_myers_liao_li_hodge_barbee_zhu_weertman_2011, title={High-pressure torsion of copper samples containing columns of highly aligned nanotwins}, volume={65}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2011.08.004}, abstractNote={Copper disks containing columns of aligned nanotwins were subjected to high-pressure torsion (HPT) involving a half turn under a 3 GPa compressive stress. The overall shear strain of 21 at 1 mm from the center of rotation is concentrated at the surfaces, where the columns of twins have been transformed into a 3-D grain structure to a depth of about 5 μm. The remaining columns of twins were sheared in the direction of the shear stress with little rotation of the twin boundaries.}, number={10}, journal={SCRIPTA MATERIALIA}, author={Shute, C. J. and Myers, B. D. and Liao, Y. and Li, S. -Y. and Hodge, A. M. and Barbee, T. W., Jr. and Zhu, Y. T. and Weertman, J. R.}, year={2011}, month={Nov}, pages={899–902} }
 @article{zou_luo_baily_zhang_haberkorn_xiong_bauer_mccleskey_burrell_civale_et al._2011, title={Highly aligned carbon nanotube forests coated by superconducting NbC}, volume={2}, ISSN={["2041-1723"]}, DOI={10.1038/ncomms1438}, abstractNote={The formation of carbon nanotube and superconductor composites makes it possible to produce new and/or improved functionalities that the individual material does not possess. Here we show that coating carbon nanotube forests with superconducting niobium carbide (NbC) does not destroy the microstructure of the nanotubes. NbC also shows much improved superconducting properties such as a higher irreversibility and upper critical field. An upper critical field value of ~5 T at 4.2 K is much greater than the 1.7 T reported in the literature for pure bulk NbC. Furthermore, the aligned carbon nanotubes induce anisotropy in the upper critical field, with a higher upper critical field occurring when the magnetic field is parallel to the carbon nanotube growth direction. These results suggest that highly oriented carbon nanotubes embedded in superconducting NbC matrix can function as defects and effectively enhance the superconducting properties of the NbC. Composites of carbon nanotubes and superconductors provide technologically important new, or improved, functionalities. Here, with a chemical solution approach, well-aligned carbon nanotube forests embedded in a superconducting NbC matrix are shown to effectively enhance the superconducting properties of NbC.}, journal={NATURE COMMUNICATIONS}, author={Zou, G. F. and Luo, H. M. and Baily, S. and Zhang, Y. Y. and Haberkorn, N. F. and Xiong, J. and Bauer, E. and McCleskey, T. M. and Burrell, A. K. and Civale, L. and et al.}, year={2011}, month={Aug} }
 @article{wang_bradford_liu_zhao_inoue_maria_li_yuan_zhu_2011, title={Mechanical and electrical property improvement in CNT/Nylon composites through drawing and stretching}, volume={71}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2011.07.023}, abstractNote={The excellent mechanical properties of carbon nanotubes (CNTs) make them the ideal reinforcements for high performance composites. The misalignment and waviness of CNTs within composites are two major issues that limit the reinforcing efficiency. We report an effective method to increase the strength and stiffness of high volume fraction, aligned CNT composites by reducing CNT waviness using a drawing and stretching approach. Stretching the composites after fabrication improved the ultimate strength by 50%, 150%, and 190% corresponding to stretch ratios of 2%, 4% and 7%, respectively. Improvement of the electrical conductivities exhibited a similar trend. These results demonstrate the importance of straightening and aligning CNTs in improving the composite strength and electrical conductivity.}, number={14}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Wang, Xin and Bradford, Philip D. and Liu, Wei and Zhao, Haibo and Inoue, Yoku and Maria, Jon-Paul and Li, Qingwen and Yuan, Fuh-Gwo and Zhu, Yuntian}, year={2011}, month={Sep}, pages={1677–1683} }
 @article{liu_zhang_xu_bradford_wang_zhao_zhang_jia_yuan_li_et al._2011, title={Producing superior composites by winding carbon nanotubes onto a mandrel under a poly(vinyl alcohol) spray}, volume={49}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2011.06.089}, abstractNote={A simple method for processing high-performance carbon nanotube (CNT)/poly(vinyl alcohol) (PVA) composites by coupling the spraying of a PVA solution with the continuous winding of CNT sheets from an array onto a rotating mandrel is reported. This method allows the CNT composites to have a high CNT volume fraction, while having a high degree of alignment, long CNTs, and good integration with the matrix, which are extremely difficult to realize simultaneously by other processes. As a result, the composites have a toughness, strength and electrical conductivity up to 100 J/g, 1.8 GPa and 780 S/cm, respectively. Such a one-step synthesis process is promising for industrial productions and also works for different types of polymers.}, number={14}, journal={CARBON}, author={Liu, Wei and Zhang, Xiaohua and Xu, Geng and Bradford, Philip D. and Wang, Xin and Zhao, Haibo and Zhang, Yingying and Jia, Quanxi and Yuan, Fuh-Gwo and Li, Qingwen and et al.}, year={2011}, month={Nov}, pages={4786–4791} }
 @article{ni_wang_liao_alhajeri_li_zhao_lavernia_ringer_langdon_zhu_et al._2011, title={Strain hardening and softening in a nanocrystalline Ni-Fe alloy induced by severe plastic deformation}, volume={528}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2011.01.017}, abstractNote={The strain response of an electrochemically deposited nanocrystalline Ni–20 wt.% Fe alloy processed by high-pressure torsion (HPT) was investigated by monitoring changes in hardness. Strain hardening was observed in the very early stage of HPT, followed by strain softening before the onset of a second strain hardening stage. Structural investigations revealed that the two hardening stages were associated with an increase in dislocation density, whereas the strain softening stage was accompanied by a reduction in the dislocation and twin densities, thereby demonstrating the main dependence of hardness on the dislocation density in this material. Grain growth occurred during HPT and its role in the hardness evolution is also discussed.}, number={9}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Ni, S and Wang, YB and Liao, XZ and Alhajeri, SN and Li, HQ and Zhao, YH and Lavernia, EJ and Ringer, SP and Langdon, TG and Zhu, YT and et al.}, year={2011}, month={Apr}, pages={3398–3403} }
 @article{ni_wang_liao_figueiredo_li_zhao_lavernia_ringer_langdon_zhu_et al._2011, title={Strain softening in nanocrystalline Ni-Fe alloy induced by large HPT revolutions}, volume={528}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2011.03.007}, abstractNote={The influence of strain on the hardness of an electrochemically deposited nanocrystalline Ni–20 wt.% Fe alloy processed by high-pressure torsion (HPT) for 20 and 30 revolutions was investigated. Strain softening followed by a stable hardness value was observed. Structural investigations revealed that, while dislocation density was important, continuous grain growth played a major role in the strain softening. The stable hardness indicates that an equilibrium structure was achieved, supporting a dynamic balance between deformation-induced grain growth and grain refinement and between deformation-induced dislocation generation and dislocation annihilation.}, number={13-14}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Ni, S and Wang, YB and Liao, XZ and Figueiredo, RB and Li, HQ and Zhao, YH and Lavernia, EJ and Ringer, SP and Langdon, TG and Zhu, YT and et al.}, year={2011}, month={May}, pages={4807–4811} }
 @article{zu_li_zhu_dey_wang_lu_deitzel_gillespie_byun_chou_2012, title={The effective interfacial shear strength of carbon nanotube fibers in an epoxy matrix characterized by a microdroplet test}, volume={50}, DOI={10.1016/j.carbon.2011.10.047}, abstractNote={The tensile properties of continuous carbon nanotube (CNT) fibers spun from a CNT carpet consisting of mainly double- and triple-walled tubes, and their interfacial properties in an epoxy matrix, are investigated by single fiber tensile tests and microdroplet tests, respectively. The average CNT fiber strength, modulus and strain to failure are 1.2 ± 0.3 GPa, 43.3 ± 7.4 GPa and 2.7 ± 0.5%, respectively. A detailed study of strength distribution of CNT fiber has been carried out. Statistical analysis shows that the CNT fiber strength is less scattered than those of MWCNTs as well as commercial carbon and glass fibers without surface treatment. The effective CNT fiber/epoxy interfacial shear strength is 14.4 MPa. Unlike traditional fiber-reinforced composites, the interfacial shear sliding occurs along the interface between regions with and without resin infiltration in the CNT fiber. Guidelines for microdroplet experiments are established through probability analysis of variables basic to specimen design.}, number={3}, journal={Carbon}, author={Zu, Mei and Li, Qingwen and Zhu, Yuntian and Dey, Moutushi and Wang, Guojian and Lu, Weibang and Deitzel, Joseph M. and Gillespie, John W., Jr. and Byun, Joon-Hyung and Chou, Tsu-Wei}, year={2012}, pages={1271–1279} }
 @article{cao_wang_figueiredo_chang_liao_kawasaki_zheng_ringer_langdon_zhu_et al._2011, title={Three-dimensional shear-strain patterns induced by high-pressure torsion and their impact on hardness evolution}, volume={59}, DOI={10.1016/j.actamat.2011.03.015}, abstractNote={The shear strain imposed on austenite/ferrite duplex stainless steel discs at different stages of high-pressure torsion (HPT) processing was imaged in plan-view and cross-section using optical microscopy and scanning electron microscopy. The effect of the shear strain was correlated to the hardness evolution of the discs. The shear-strain patterns are complex and are different on the top and bottom surfaces of the discs. A double-swirl pattern emerged on the top surface in the early stages of HPT. These two centres of the swirl moved towards the centre of the disc as the numbers of HPT revolutions was increased and ultimately the double-swirl evolved into a single-swirl. Less regular shear-strain patterns were observed on the bottom surfaces of the discs. Multiple ring-like patterns with mirror symmetry over the central axes of the discs were visible from cross-sectional observations. Nanoindentation testing on the two surfaces and a cross-section of HPT discs showed that the hardness is insensitive to specific shear-strain patterns, but is closely related to the widths of the austenite and ferrite phase domains. Late in the deformation process, the hardness in the interior of an HPT disc may be higher than at either of the disc surfaces because of the development of finer microstructural phase distributions.}, number={10}, journal={Acta Materialia}, author={Cao, Y and Wang, YB and Figueiredo, RB and Chang, L and Liao, XZ and Kawasaki, M and Zheng, WL and Ringer, SP and Langdon, TG and Zhu, YT and et al.}, year={2011}, pages={3903–3914} }
 @article{bradford_wang_zhao_zhu_2011, title={Tuning the compressive mechanical properties of carbon nanotube foam}, volume={49}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2011.03.012}, abstractNote={A post-growth chemical vapor deposition (CVD) treatment was used to tune the compressive mechanical properties of carbon nanotube (CNT) arrays. Millimeter tall CNT arrays with low compressive resilience were changed to a foam-like material with high compressive strength and almost complete recovery upon unloading. The foam was tuned to provide a range of compressive properties for various applications. The treated arrays demonstrated compressive strength up to 35× greater than the as-grown CNT array. Unlike polymeric foams, the CNT foam did not decompose after exposure to high temperatures. Investigation of the foam structure revealed that the CVD treatment increased CNT diameter through radial growth, while increasing the CNT surface roughness. The morphological changes help to explain the increase in CNT array compressive strength and the transition from permanent array deformation to foam-like recovery after compressive loading.}, number={8}, journal={CARBON}, author={Bradford, Philip D. and Wang, Xin and Zhao, Haibo and Zhu, Y. T.}, year={2011}, month={Jul}, pages={2834–2841} }
 @article{zhang_li_mara_zhu_minor_huang_2010, title={"Mechanical Behavior of Nanostructured Materials"}, volume={41A}, ISSN={["1073-5623"]}, DOI={10.1007/s11661-010-0205-7}, abstractNote={The symposium, ''Mechanical Behavior of Nanostructured Materials,'' was held during the 2009 TMS Annual Meeting from February 15 to 19 in San Francisco, California.The symposium focused on understanding the mechanical behavior of ultra-fine-grained and nanostructured materials in the form of bulk, thin films, and nanowires.There is a good mixture of advanced experimental as well as theoretical and computational presentations in the symposium.Topics presented include the following: (1) synthesis and microstructural characterization of nanomaterials; (2) nanomechanics; (3) fatigue and fracture of nanomaterials; (4) deformation, plasticity, and creep in nanomaterials; (5) mechanical and thermal stability; (6) advanced characterization techniques including in-situ techniques and advances in nanomechanical testing techniques; and (7) theoretical, computational, and analytical modeling of mechanical properties of nanomaterials.Numerous articles in this special issue report the important results and perspectives presented in this symposium.}, number={4}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={Zhang, Xinghang and Li, Xiaodong and Mara, Nathan and Zhu, Yuntian and Minor, Andrew and Huang, Rui}, year={2010}, month={Apr}, pages={777–777} }
 @article{bradford_wang_zhao_maria_jia_zhu_2010, title={A novel approach to fabricate high volume fraction nanocomposites with long aligned carbon nanotubes}, volume={70}, ISSN={["1879-1050"]}, DOI={10.1016/j.compscitech.2010.07.020}, abstractNote={Conventional micro-fiber-reinforced composites provide insight into critical structural features needed for obtaining maximum composite strength and stiffness: the reinforcements should be long, well aligned in a unidirectional orientation, and should have a high reinforcement volume fraction. It has long been a challenge for researchers to process CNT composites with such structural features. Here we report a method to quickly produce macroscopic CNT composites with a high volume fraction of millimeter long, well aligned CNTs. Specifically, we use the novel method, shear pressing, to process tall, vertically aligned CNT arrays into dense aligned CNT preforms, which are subsequently processed into composites. Alignment was confirmed through SEM analysis while a CNT volume fraction in the composites was calculated to be 27%, based on thermogravimetric analysis data. Tensile testing of the preforms and composites showed promising mechanical properties with tensile strengths reaching 400 MPa.}, number={13}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Bradford, Philip D. and Wang, Xin and Zhao, Haibo and Maria, Jon-Paul and Jia, Quanxi and Zhu, Y. T.}, year={2010}, month={Nov}, pages={1980–1985} }
 @article{zhao_bradford_wang_liu_luo_jia_zhu_yuan_2010, title={An intermetallic Fe-Zr catalyst used for growing long carbon nanotube arrays}, volume={64}, ISSN={["1873-4979"]}, DOI={10.1016/j.matlet.2010.05.045}, abstractNote={Metallic nanoparticles containing single and binary components have been known for their catalytic properties to grow carbon nanotube (CNT) arrays. In this paper, an intermetallic catalyst consisting of iron and zirconium was used to grow millimeter long, well aligned arrays. The Fe–Zr catalysts enabled the growth of 1.7 mm-long carbon nanotube arrays in 45 min. A comparison with pure iron catalyst indicated that adding Zr to iron can stabilize the Fe catalyst at the CNT growth temperature and moderate its reactivity. SEM images showed the different growth behaviors for Fe–Zr and Fe catalysts. The long, uniform CNT arrays grown here have potential applications in many advanced composites.}, number={18}, journal={MATERIALS LETTERS}, author={Zhao, Haibo and Bradford, Philip D. and Wang, Xin and Liu, Wei and Luo, Tzy Jiun Mark and Jia, Quanxi and Zhu, Yuntian and Yuan, Fuh-Gwo}, year={2010}, month={Sep}, pages={1947–1950} }
 @article{zhao_zhang_bradford_zhou_jia_yuan_zhu_2010, title={Carbon nanotube yarn strain sensors}, volume={21}, ISSN={["1361-6528"]}, DOI={10.1088/0957-4484/21/30/305502}, abstractNote={Carbon nanotube (CNT) based sensors are often fabricated by dispersing CNTs into different types of polymer. In this paper, a prototype carbon nanotube (CNT) yarn strain sensor with excellent repeatability and stability for in situ structural health monitoring was developed. The CNT yarn was spun directly from CNT arrays, and its electrical resistance increased linearly with tensile strain, making it an ideal strain sensor. It showed consistent piezoresistive behavior under repetitive straining and unloading, and good resistance stability at temperatures ranging from 77 to 373 K. The sensors can be easily embedded into composite structures with minimal invasiveness and weight penalty. We have also demonstrated their ability to monitor crack initiation and propagation.}, number={30}, journal={NANOTECHNOLOGY}, author={Zhao, Haibo and Zhang, Yingying and Bradford, Philip D. and Zhou, Qian and Jia, Quanxi and Yuan, Fuh-Gwo and Zhu, Yuntian}, year={2010}, month={Jul} }
 @article{wu_youssef_koch_mathaudhu_kecskes_zhu_2011, title={Deformation twinning in a nanocrystalline hcp Mg alloy}, volume={64}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2010.10.024}, abstractNote={Nanocrystalline (nc) hexagonal close-packed (hcp) metals are rarely observed to deform by twinning, which is contrary to face-centered cubic metals. Here we report that, after alloying Mg with 10 at.% Ti, deformation twins are observed in an nc Mg–Ti alloy processed by mechanical attrition. The formation of deformation twins is attributed to the alloying effect, which may change the energy path for twinning. These results point to a promising approach to design nc hcp alloys for superior mechanical properties.}, number={3}, journal={SCRIPTA MATERIALIA}, author={Wu, X. L. and Youssef, K. M. and Koch, C. C. and Mathaudhu, S. N. and Kecskes, L. J. and Zhu, Y. T.}, year={2011}, month={Feb}, pages={213–216} }
 @article{zhu_wu_liao_narayan_kecskes_mathaudhu_2011, title={Dislocation-twin interactions in nanocrystalline fcc metals}, volume={59}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2010.10.028}, abstractNote={Dislocation interaction with and accumulation at twin boundaries have been reported to significantly improve the strength and ductility of nanostructured face-centered cubic (fcc) metals and alloys. Here we systematically describe plausible dislocation interactions at twin boundaries. Depending on the characteristics of the dislocations and the driving stress, possible dislocation reactions at twin boundaries include cross-slip into the twinning plane to cause twin growth or de-twinning, formation of a sessile stair-rod dislocation at the twin boundary, and transmission across the twin boundary. The energy barriers for these dislocation reactions are described and compared.}, number={2}, journal={ACTA MATERIALIA}, author={Zhu, Y. T. and Wu, X. L. and Liao, X. Z. and Narayan, J. and Kecskes, L. J. and Mathaudhu, S. N.}, year={2011}, month={Jan}, pages={812–821} }
 @article{sarma_jian_wang_conrad_zhu_2010, title={Effect of rolling temperature on the evolution of defects and properties of an Al-Cu alloy}, volume={45}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-010-4484-6}, number={17}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Sarma, V. Subramanya and Jian, W. W. and Wang, J. and Conrad, H. and Zhu, Y. T.}, year={2010}, month={Sep}, pages={4846–4850} }
 @article{ni_wang_liao_alhajeri_li_ringer_langdon_zhu_wang_figueiredo_et al._2011, title={Grain Size Effect on Deformation Twinning and De-Twinning in a Nanocrystalline Ni-Fe Alloy}, volume={667-669}, DOI={10.4028/www.scientific.net/MSF.667-669.181}, abstractNote={The effect of grain size on the deformation twinning and de-twinning in a nanocrystalline Ni-Fe alloy was investigated using transmission electron microscopy. Specimens with different grain sizes were obtained by severely deforming an electrochemically deposited nanocrystalline Ni-20wt.% Fe alloy using high-pressure torsion, which resulted in continuous grain growth from an average grain size of ~ 21 nm in the as-deposited material to ~ 72 nm for the highest strain applied in this study. Results show that deformation de-twinning occurs at very small grain sizes while deformation twinning takes place when the grain size is larger than ~ 45 nm. The mechanism of the observed grain size effect on twinning and de-twinning is briefly discussed.}, journal={Nanomaterials By Severe Plastic Deformation: Nanospd5, Pts 1 and 2}, author={Ni, S. and Wang, Y. B. and Liao, X. Z. and Alhajeri, S. N. and Li, H. Q. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T. and Wang, JT and Figueiredo, RB and et al.}, year={2011}, pages={181–186} }
 @article{ni_wang_liao_alhajeri_li_zhao_lavernia_ringer_langdon_zhu_et al._2011, title={Grain growth and dislocation density evolution in a nanocrystalline Ni-Fe alloy induced by high-pressure torsion}, volume={64}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2010.10.027}, abstractNote={The structural evolution of a nanocrystalline Ni–Fe alloy induced by high-pressure torsion (HPT) was investigated. HPT-induced grain growth occurred via grain rotation and coalescence, forming three-dimensional small-angle sub-grain boundaries. Further deformation eliminates the sub-grain boundaries from which dislocations glide away on different {1 1 1} planes. A significant number of these dislocations come together to form Lomer–Cottrell locks that effectively increase the dislocation storage capacity of the nanocrystalline material. These observations may help with developing strong and ductile nanocrystalline materials.}, number={4}, journal={SCRIPTA MATERIALIA}, author={Ni, S and Wang, YB and Liao, XZ and Alhajeri, SN and Li, HQ and Zhao, YH and Lavernia, EJ and Ringer, SP and Langdon, TG and Zhu, YT and et al.}, year={2011}, month={Feb}, pages={327–330} }
 @article{wang_zhao_lian_liao_valiev_ringer_zhu_lavernia_2010, title={Grain size and reversible beta-to-omega phase transformation in a Ti alloy}, volume={63}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2010.05.045}, abstractNote={We report a significant grain size effect on the phase transformation in a Ti–36Nb–2.2Ta–3.7Zr–0.3O alloy during severe plastic deformation. For grain sizes larger than the submicrometer range, the body-centered cubic β phase transformed to hexagonal ω phase when deformed by high-pressure torsion under a relatively low pressure of 3 GPa and at room temperature. However, a reverse ω to β transformation was observed under the same deformation conditions when the grain sizes were less than 100 nm.}, number={6}, journal={SCRIPTA MATERIALIA}, author={Wang, Y. B. and Zhao, Y. H. and Lian, Q. and Liao, X. Z. and Valiev, R. Z. and Ringer, S. P. and Zhu, Y. T. and Lavernia, E. J.}, year={2010}, month={Sep}, pages={613–616} }
 @article{li_zhao_liu_xu_horita_liao_zhu_langdon_lavernia_2010, title={Influence of grain size on the density of deformation twins in Cu-30%Zn alloy}, volume={527}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2010.02.076}, abstractNote={Mechanical properties of nanostructured (NS) materials are significantly affected by both grain size and twin density, and the twin density has a close relationship with the grain size. Therefore, it is fundamentally important to understand the influence of grain size on the density of deformation twins in NS materials. In this study, we selected Cu–30%Zn alloy as a model material to study this phenomenon, because it has low stacking fault energy of 7 mJ m−2 and twinning is its dominant deformation mechanism. High-pressure torsion (HPT), equal channel pressing (ECAP) and ECAP followed by rolling were used to achieve a wide range of grain size from about 3 μm to 70 nm. It is found that, with decreasing grain size, the average distance between deformation twins decreases gradually from 177 nm to 24 nm, while the density of deformation twins (the length of twin boundary in unit area) exhibit a maximum value at ECAP + 95% rolling sample with average grain size of 110 nm. Careful statistics analysis reveals two optimum grain size ranges 60–80 nm and 40–50 nm for maximum twin density values for ECAP + 95% rolling and HPT Cu–30%Zn samples, respectively. The underlying mechanisms governing the influence of grain size on twinning is discussed.}, number={16-17}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Y. and Zhao, Y. H. and Liu, W. and Xu, C. and Horita, Z. and Liao, X. Z. and Zhu, Y. T. and Langdon, T. G. and Lavernia, E. J.}, year={2010}, month={Jun}, pages={3942–3948} }
 @article{kaddurah-daouk_baillie_zhu_zeng_wiest_nguyen_watkins_krauss_2010, title={Lipidomic analysis of variation in response to simvastatin in the Cholesterol and Pharmacogenetics Study}, volume={6}, ISSN={1573-3882 1573-3890}, url={http://dx.doi.org/10.1007/s11306-010-0207-x}, DOI={10.1007/s11306-010-0207-x}, abstractNote={Statins are commonly used for reducing cardiovascular disease risk but therapeutic benefit and reductions in levels of low-density lipoprotein cholesterol (LDL-C) vary among individuals. Other effects, including reductions in C-reactive protein (CRP), also contribute to treatment response. Metabolomics provides powerful tools to map pathways implicated in variation in response to statin treatment. This could lead to mechanistic hypotheses that provide insight into the underlying basis for individual variation in drug response. Using a targeted lipidomics platform, we defined lipid changes in blood samples from the upper and lower tails of the LDL-C response distribution in the Cholesterol and Pharmacogenetics study. Metabolic changes in responders are more comprehensive than those seen in non-responders. Baseline cholesterol ester and phospholipid metabolites correlated with LDL-C response to treatment. CRP response to therapy correlated with baseline plasmalogens, lipids involved in inflammation. There was no overlap of lipids whose changes correlated with LDL-C or CRP responses to simvastatin suggesting that distinct metabolic pathways govern statin effects on these two biomarkers. Metabolic signatures could provide insights about variability in response and mechanisms of action of statins. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-010-0207-x) contains supplementary material, which is available to authorized users.}, number={2}, journal={Metabolomics}, publisher={Springer Nature}, author={Kaddurah-Daouk, Rima and Baillie, Rebecca A. and Zhu, Hongjie and Zeng, Zhao-Bang and Wiest, Michelle M. and Nguyen, Uyen Thao and Watkins, Steven M. and Krauss, Ronald M.}, year={2010}, month={Apr}, pages={191–201} }
 @article{liddicoat_liao_zhao_zhu_murashkin_lavernia_valiev_ringer_2010, title={Nanostructural hierarchy increases the strength of aluminium alloys}, volume={1}, DOI={10.1038/ncomms1062}, abstractNote={Increasing the strength of metallic alloys while maintaining formability is an interesting challenge for enabling new generations of lightweight structures and technologies. In this paper, we engineer aluminium alloys to contain a hierarchy of nanostructures and possess mechanical properties that expand known performance boundaries—an aerospace-grade 7075 alloy exhibits a yield strength and uniform elongation approaching 1 GPa and 5%, respectively. The nanostructural architecture was observed using novel high-resolution microscopy techniques and comprises a solid solution, free of precipitation, featuring (i) a high density of dislocations, (ii) subnanometre intragranular solute clusters, (iii) two geometries of nanometre-scale intergranular solute structures and (iv) grain sizes tens of nanometres in diameter. Our results demonstrate that this novel architecture offers a design pathway towards a new generation of super-strong materials with new regimes of property-performance space. Improving the properties of metallic alloys is important to develop new lightweight materials. In this paper, we show that an aluminium (Al) alloy containing a hierarchy of nanostructures in a solid solution with a high density of dislocations is capable of beating strength records for Al alloys while maintaining good ductility.}, journal={Nature Communications}, author={Liddicoat, PV and Liao, XZ and Zhao, YH and Zhu, Y.T. and Murashkin, MY and Lavernia, EJ and Valiev, RZ and Ringer, SP}, year={2010} }
 @article{koch_scattergood_youssef_chan_zhu_2010, title={Nanostructured materials by mechanical alloying: new results on property enhancement}, volume={45}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-010-4252-7}, number={17}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Koch, Carl C. and Scattergood, Ronald O. and Youssef, Khaled M. and Chan, Ethan and Zhu, Yuntian T.}, year={2010}, month={Sep}, pages={4725–4732} }
 @article{zhang_sheehan_zhai_zou_luo_xiong_zhu_jia_2010, title={Polymer-Embedded Carbon Nanotube Ribbons for Stretchable Conductors}, volume={22}, DOI={10.1002/adma.200904426}, abstractNote={The creation of stretchable electronics is emerging as one of the most interesting research topics in materials science and technology. [ 1,2 ] Devices that are stretchable, foldable, and deformable into complex curvilinear shapes can enable many new applications that would be impossible to achieve by conventional rigid electronics. Examples of such applications range from fl exible displays, electronic eyeball cameras to stretchable electronic implants and conformable skin sensors. [ 3–6 ]}, number={28}, journal={Advanced Materials}, author={Zhang, YY and Sheehan, CJ and Zhai, JY and Zou, GF and Luo, HM and Xiong, J and Zhu, Y.T. and Jia, QX}, year={2010}, pages={3027–3031} }
 @article{zhu_mathaudhu_goken_langdon_lowe_semiatin_tsuji_zhao_2010, title={Preface to the Special Issue on Ultrafine Grained Materials}, volume={45}, ISSN={["0022-2461"]}, DOI={10.1007/s10853-010-4709-8}, number={17}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Zhu, Yuntian T. and Mathaudhu, Suveen N. and Goken, Mathias and Langdon, Terence G. and Lowe, Terry C. and Semiatin, S. Lee and Tsuji, Nobuhiro and Zhao, Yong Hao}, year={2010}, month={Sep}, pages={4543–4544} }
 @article{zhu_valiev_langdon_tsuji_lu_2010, title={Processing of nanostructured metals and alloys via plastic deformation}, volume={35}, number={12}, journal={Mrs Bulletin}, author={Zhu, YT and Valiev, RZ and Langdon, TG and Tsuji, N and Lu, K}, year={2010}, pages={977–981} }
 @article{sarma_wang_jian_kauffmann_conrad_freudenberger_zhu_2010, title={Role of stacking fault energy in strengthening due to cryo-deformation of FCC metals}, volume={527}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2010.08.015}, abstractNote={The effectiveness of the cryogenic (CT) rolling vis-à-vis room temperature (RT) rolling on strengthening is significantly affected by stacking fault energy (SFE) and there is an optimum SFE at which CT rolling is most effective. Studies on Al, Al alloy AA6061, Cu, Cu–4.6Al, Cu–9Al and Cu–15Al (in at.%) alloys revealed that in metals with very high and very low SFEs, the strength difference between CT and RT rolled samples is <10%. The Cu–4.6Al alloy with an intermediate SFE revealed maximum enhancement of strength (25–30%). These results are explained by changes in deformation mechanisms with SFE and temperature. High SFE metals deformed by dislocation slip and low SFE metals deformed by twinning during CT and RT rolling. Metals with intermediate SFEs deformed by twinning during CT rolling but by dislocation slip during RT rolling, and this makes the CT rolling most effective over RT rolling in enhancing the strength.}, number={29-30}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Sarma, V. Subramanya and Wang, J. and Jian, W. W. and Kauffmann, A. and Conrad, H. and Freudenberger, J. and Zhu, Y. T.}, year={2010}, month={Nov}, pages={7624–7630} }
 @article{zhao_zhu_lavernia_2010, title={Strategies for Improving Tensile Ductility of Bulk Nanostructured Materials}, volume={12}, ISSN={["1527-2648"]}, DOI={10.1002/adem.200900335}, abstractNote={AbstractThe low ductility that is consistently associated with bulk nanostructured (NS) materials has been identified as perhaps the single most critical issue that must be resolved before this novel class of materials can be used in a wide variety of applications. Not surprisingly, a number of published studies, published mostly after 2000, identify the issue of low ductility and describe strategies to improve ductility. Details of these strategies were discussed in review papers published by Koch and Ma in 2005 and 2006, respectively.15,16 In view of continued efforts and recent results, in this paper we describe progress in attempting to address the low ductility of NS materials, after 2006. We first analyze the fundamental reasons for the observed low ductility of bulk NS materials, and summarize early (prior to 2006) attempts to enhance the ductility of bulk NS materials, which often sacrificed the strength. Then, we review recent progress in developing strategies for improving the tensile ductility of bulk NS materials, which involve mainly microstructure modifications, after 2006. Different from early efforts, these new strategies strive to increase the tensile ductility while increasing/maintaining the strength simultaneously. In addition, the influence of tensile testing conditions, including temperature, strain rate, tensile specimen size and geometry, and strain measurement methods, on tensile ductility of NS materials will also be reviewed. Finally, we identify several issues that will require further, in depth analysis in the future.}, number={8}, journal={ADVANCED ENGINEERING MATERIALS}, author={Zhao, Yonghao and Zhu, Yuntian and Lavernia, Enrique J.}, year={2010}, month={Aug}, pages={769–778} }
 @article{hwang_singh_chaudhari_tiley_zhu_du_banerjee_2010, title={Templated Growth of Hexagonal Nickel Carbide Nanocrystals on Vertically Aligned Carbon Nanotubes}, volume={114}, ISSN={["1932-7447"]}, DOI={10.1021/jp102571g}, abstractNote={Article discussing the templated growth of hexagonal nickel carbon nanocrystals on vertically aligned carbon nanotubes.}, number={23}, journal={JOURNAL OF PHYSICAL CHEMISTRY C}, author={Hwang, Jun Y. and Singh, Antariksh R. P. and Chaudhari, Mrunalkumar and Tiley, Jaimie and Zhu, Yuntian and Du, Jincheng and Banerjee, Rajarshi}, year={2010}, month={Jun}, pages={10424–10429} }
 @article{deng_lu_zhao_zhu_kim_chou_2011, title={The properties of dry-spun carbon nanotube fibers and their interfacial shear strength in an epoxy composite}, volume={49}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2010.12.061}, abstractNote={Continuous fibers composed of carbon nanotubes have been adopted as reinforcements for polymeric composites. This paper presents several fundamental studies relevant to the mechanical behavior of CNT fibers, including fiber tensile behavior; in situ SEM observation of fiber deformation mechanisms; and fiber modulus, ultimate strength and fracture strain measurements. A modified Weibull strength distribution model that takes into account the flaw density variation with fiber diameter has been adopted for the statistical strength analysis. The interfacial shear strength between the carbon nanotube fiber and the epoxy matrix has been measured using fragmentation tests of single-fiber composites.}, number={5}, journal={CARBON}, author={Deng, Fei and Lu, Weibang and Zhao, Haibo and Zhu, Yuntian and Kim, Byung-Sun and Chou, Tsu-Wei}, year={2011}, month={Apr}, pages={1752–1757} }
 @article{wang_liao_zhao_lavernia_ringer_horita_langdon_zhu_2010, title={The role of stacking faults and twin boundaries in grain refinement of a Cu-Zn alloy processed by high-pressure torsion}, volume={527}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2010.04.036}, abstractNote={A recent model developed to predict the smallest grain sizes obtainable by severe plastic deformation has worked well for materials with medium to high stacking fault energies (SFEs) but not for those with low SFEs. To probe this issue, experiments were conducted using a Cu–30 wt.% Zn alloy with a very low SFE of 7 mJ/m2 as the model material. High-pressure torsion was used as the grain refinement technique. The results indicate that stacking faults and twin boundaries play a key role in the grain refinement process such that the smallest achievable grain size is determined by the highest stacking fault and twin density that the system is able to produce. An amorphization of grain boundaries was also observed in the final structure. These observations are very different from those reported for materials having medium to high SFEs and they confirm the operation of a different grain refinement mechanism.}, number={18-19}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Wang, Y. B. and Liao, X. Z. and Zhao, Y. H. and Lavernia, E. J. and Ringer, S. P. and Horita, Z. and Langdon, T. G. and Zhu, Y. T.}, year={2010}, month={Jul}, pages={4959–4966} }
 @article{cao_kawasaki_wang_alhajeri_liao_zheng_ringer_zhu_langdon_2010, title={Unusual macroscopic shearing patterns observed in metals processed by high-pressure torsion}, volume={45}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-010-4485-5}, number={17}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Cao, Y. and Kawasaki, M. and Wang, Y. B. and Alhajeri, S. N. and Liao, X. Z. and Zheng, W. L. and Ringer, S. P. and Zhu, Y. T. and Langdon, T. G.}, year={2010}, month={Sep}, pages={4545–4553} }
 @article{zhang_stan_xu_wang_doorn_htoon_zhu_jia_2009, title={A double-layered carbon nanotube array with super-hydrophobicity}, volume={47}, ISSN={["1873-3891"]}, DOI={10.1016/j.carbon.2009.07.056}, abstractNote={The growth of double-layered vertical-aligned carbon nanotube (CNT) arrays by a single step chemical vapor deposition is reported. The deactivation and reactivation of catalyst particles may be the cause of such a growth process. An interesting morphology difference between the top and the bottom CNT layers was observed. In contrast to the smooth surface of the top CNT layer, the surface of the bottom layer shows hierarchical structures. The surface structures of the bottom CNT layer allow this surface to exhibit super-hydrophobic properties and excellent self-cleaning abilities.}, number={14}, journal={CARBON}, author={Zhang, Yingying and Stan, Liliana and Xu, Ping and Wang, Hsing-Lin and Doorn, Stephen K. and Htoon, Han and Zhu, Yuntian and Jia, Quanxi}, year={2009}, month={Nov}, pages={3332–3336} }
 @article{cao_wang_alhajeri_liao_zheng_ringer_langdon_zhu_2010, title={A visualization of shear strain in processing by high-pressure torsion}, volume={45}, ISSN={["1573-4803"]}, DOI={10.1007/s10853-009-3998-2}, number={3}, journal={JOURNAL OF MATERIALS SCIENCE}, author={Cao, Y. and Wang, Y. B. and Alhajeri, S. N. and Liao, X. Z. and Zheng, W. L. and Ringer, S. P. and Langdon, T. G. and Zhu, Y. T.}, year={2010}, month={Feb}, pages={765–770} }
 @book{zehetbauer_zhu_2009, title={Bulk nanostructured materials}, ISBN={9783527315246}, publisher={Weinheim: Wiley-VCH}, year={2009} }
 @article{wang_ho_cao_al._2009, title={Dislocation density evolution during high pressure torsion of a nanocrystalline Ni-Fe alloy}, volume={94}, DOI={10.1063/1.3095852}, abstractNote={High-pressure torsion (HPT) induced dislocation density evolution in a nanocrystalline Ni-20 wt %Fe alloy was investigated using x-ray diffraction and transmission electron microscopy. Results suggest that the dislocation density evolution is fundamentally different from that in coarse-grained materials. The HPT process initially reduces the dislocation density within nanocrystalline grains and produces a large number of dislocations located at small-angle subgrain boundaries that are formed via grain rotation and coalescence. Continuing the deformation process eliminates the subgrain boundaries but significantly increases the dislocation density in grains. This phenomenon provides an explanation of the mechanical behavior of some nanostructured materials.}, number={9}, journal={APPLIED PHYSICS LETTERS}, author={WANG, YB and HO, JC and CAO, Y and al.}, year={2009} }
 @article{wang_ho_cao_liao_li_zhao_lavernia_ringer_zhu_2009, title={Dislocation density evolution during high pressure torsion of a nanocrystalline Ni-Fe alloy}, volume={94}, number={9}, journal={Applied Physics Letters}, author={Wang, Y. B. and Ho, J. C. and Cao, Y. and Liao, X. Z. and Li, H. Q. and Zhao, Y. H. and Lavernia, E. J. and Ringer, S. P. and Zhu, Y. T.}, year={2009} }
 @article{zhao_lia_topping_liao_zhu_valiev_lavernia_2009, title={Ductility of ultrafine-grained copper processed by equal-channel angular pressing}, volume={100}, DOI={10.3139/146.110232}, abstractNote={AbstractIn a previous study (R.Z. Valiev et al.: J. Mater. Res. 17 (2002) 5), unusual combinations of yield strength and ductility in ultrafine grained copper processed by equal-channel angular pressing of 360 MPa 23 % (by Bc route two passes) and 380 MPa 55 % (by Bc route 16 passes) were reported. However, results from recent work suggest that the tensile strain, when measured using a non-standard method and miniature dog-bone tensile specimens, is likely to contain significant errors. In this study, by implementing a standard strain measurement and tensile specimens with geometries that meet the ASTM requirements, we report yield strength and ductility combinations of 370 MPa 9 % (Bc 2 passes) and 370 MPa 16 % (Bc 16 passes) in the ultrafine grained copper. The higher ductility of the ultrafine grained copper processed by route Bc 16 passes was rationalized on the basis of several factors including the presence of equiaxed grains, lower dislocation density and higher fraction of high-angle grain boundaries (which result in larger strain rate sensitivity and strain hardening).}, number={12}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={ZHAO, YH and LIA, Y and TOPPING, TD and LIAO, XZ and ZHU, YD and VALIEV, RZ and LAVERNIA, EJ}, year={2009}, pages={1647–1652} }
 @article{sun_zhao_cooley_kassner_horita_langdon_lavernia_zhu_2009, title={Effect of stacking fault energy on strength and ductility of nanostructured alloys: An evaluation with minimum solution hardening}, volume={525}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2009.06.030}, abstractNote={The effect of stacking fault energy (SFE) on the mechanical properties was investigated in Ni–Co alloys which have minimum solution hardening effects. Cobalt reduces the SFE in nickel and this promotes grain refinement during processing and increases the dislocation and twin densities. A reduction in SFE increases strength and tensile ductility. The higher strength is due to grain refinement and higher dislocation and pre-existing twin densities whereas the higher ductility is attributed to a higher work hardening rate.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Sun, Pei-Ling and Zhao, Y. H. and Cooley, J. C. and Kassner, M. E. and Horita, Z. and Langdon, T. G. and Lavernia, E. J. and Zhu, Y. T.}, year={2009}, month={Nov}, pages={83–86} }
 @article{peng_sun_cai_chen_zhu_liao_chen_li_lu_zhu_et al._2009, title={Electrochromatic carbon nanotube/polydiacetylene nanocomposite fibres}, volume={4}, ISSN={["1748-3395"]}, DOI={10.1038/NNANO.2009.264}, abstractNote={Chromatic materials such as polydiacetylene change colour in response to a wide variety of environmental stimuli, including changes in temperature, pH and chemical or mechanical stress, and have been extensively explored as sensing devices. Here, we report the facile synthesis of carbon nanotube/polydiacetylene nanocomposite fibres that rapidly and reversibly respond to electrical current, with the resulting colour change being readily observable with the naked eye. These composite fibres also chromatically respond to a broad spectrum of other stimulations. For example, they exhibit rapid and reversible stress-induced chromatism with negligible elongation. These electrochromatic nanocomposite fibres could have various applications in sensing.}, number={11}, journal={NATURE NANOTECHNOLOGY}, author={Peng, Huisheng and Sun, Xuemei and Cai, Fangjing and Chen, Xuli and Zhu, Yinchao and Liao, Guipan and Chen, Daoyong and Li, Qingwen and Lu, Yunfeng and Zhu, Yuntian and et al.}, year={2009}, month={Nov}, pages={738–741} }
 @article{zhu_narayan_hirth_mahajan_wu_liao_2009, title={Formation of single and multiple deformation twins in nanocrystalline fcc metals}, volume={57}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2009.04.020}, abstractNote={Deformation twins are often observed to meet each other to form multi-fold twins in nanostructured face-centered cubic (fcc) metals. Here we propose two types of mechanism for the nucleation and growth of four different single and multiple twins. These mechanisms provide continuous generation of twinning partials for the growth of the twins after nucleation. A relatively high stress or high strain rate is needed to activate these mechanisms, making them more prevalent in nanocrystalline materials than in their coarse-grained counterparts. Experimental observations that support the proposed mechanisms are presented.}, number={13}, journal={ACTA MATERIALIA}, author={Zhu, Y. T. and Narayan, J. and Hirth, J. P. and Mahajan, S. and Wu, X. L. and Liao, X. Z.}, year={2009}, month={Aug}, pages={3763–3770} }
 @article{wang_liao_zhu_2009, title={Grain refinement and growth induced by severe plastic deformation}, volume={100}, DOI={10.3139/146.110230}, abstractNote={AbstractSevere plastic deformation techniques have been widely used to produce bulk ultrafine-grained and nanocrystalline materials. Severe plastic deformation of materials is a complex process that includes both grain refinement via the activities of dislocations and twinning, and grain growth. In this paper, we present a short review on the mechanisms of grain refinement and grain growth induced by severe plastic deformation.}, number={12}, journal={INTERNATIONAL JOURNAL OF MATERIALS RESEARCH}, author={WANG, YB and LIAO, XZ and ZHU, YT}, year={2009}, pages={1632–1637} }
 @inproceedings{wang_liao_zhu_2009, title={Grain refinement and growth induced by severe plastic deformation}, volume={100}, number={12}, booktitle={International Journal of Materials Research}, author={Wang, Y. B. and Liao, X. Z. and Zhu, Y. T.}, year={2009}, pages={1632–1637} }
 @article{wang_louie_cao_liao_li_ringer_zhu_2010, title={High-pressure torsion induced microstructural evolution in a hexagonal close-packed Zr alloy}, volume={62}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2009.10.034}, abstractNote={Transmission electron microscopy was used to investigate the microstructural evolution of a hexagonal close-packed Zr alloy subjected to high-pressure torsion at 3.8 GPa. Results show that an inhomogeneous grain size distribution was obtained at the early stages of deformation, which is unique to hexagonal structures. {1¯011} deformation twins, which have never been reported in Zr alloys, were observed in coarse grains but not in refined grains. The grain refinement mechanism is discussed based on the experimental observation.}, number={4}, journal={SCRIPTA MATERIALIA}, author={Wang, Y. B. and Louie, M. and Cao, Y. and Liao, X. Z. and Li, H. J. and Ringer, S. P. and Zhu, Y. T.}, year={2010}, month={Feb}, pages={214–217} }
 @article{zhao_guo_wei_topping_dangelewicz_zhu_langdon_lavernia_2009, title={Influence of specimen dimensions and strain measurement methods on tensile stress-strain curves}, volume={525}, ISSN={["1873-4936"]}, DOI={10.1016/j.msea.2009.06.031}, abstractNote={Miniature tensile specimens, having various sizes and geometries, are often used to measure the mechanical properties of bulk nanostructured materials. However, these samples are generally too small for use with conventional extensometers so that the strains are usually calculated from the crosshead displacements. This study uses experimental results and finite element modeling (FEM) to critically evaluate the influence of the specimen dimensions and strain measurement methods on the tensile curves obtained from miniature specimens. Using coarse-grained Cu as a model material, the results demonstrate that the values of strain obtained from the crosshead displacement are critically influenced by the specimen dimensions such that the uniform elongation and the post-necking elongation both increase with decreasing gauge length and increasing specimen thickness. The results provide guidance on the optimum procedures for the tensile testing of miniature specimens of both coarse-grained and nanostructured materials.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Zhao, Y. H. and Guo, Y. Z. and Wei, Q. and Topping, T. D. and Dangelewicz, A. M. and Zhu, Y. T. and Langdon, T. G. and Lavernia, E. J.}, year={2009}, month={Nov}, pages={68–77} }
 @article{wang_ho_liao_al._2009, title={Mechanism of grain growth during severe plastic deformation of a nanocrystalline Ni-Fe alloy}, volume={94}, DOI={10.1063/1.3065025}, abstractNote={Deformation induced grain growth has been widely reported in nanocrystalline materials. However, the grain growth mechanism remains an open question. This study applies high-pressure torsion to severely deform bulk nanocrystalline Ni-20 wt % Fe disks and uses transmission electron microscopy to characterize the grain growth process. Our results provide solid evidence suggesting that high pressure torsion induced grain growth is achieved primarily via grain rotation for grains much smaller than 100 nm. Dislocations are mainly seen at small-angle subgrain boundaries during the grain growth process but are seen everywhere in grains after the grains have grown large.}, number={1}, journal={APPLIED PHYSICS LETTERS}, author={WANG, YB and HO, JC and LIAO, XZ and al.}, year={2009} }
 @article{wang_ho_liao_li_ringer_zhu_2009, title={Mechanism of grain growth during severe plastic deformation of a nanocrystalline Ni-Fe alloy}, volume={94}, number={1}, journal={Applied Physics Letters}, author={Wang, Y. B. and Ho, J. C. and Liao, X. Z. and Li, H. Q. and Ringer, S. P. and Zhu, Y. T.}, year={2009} }
 @article{li_misra_zhu_horita_koch_holesinger_2009, title={Processing and characterization of nanostructured Cu-carbon nanotube composites}, volume={523}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2009.05.031}, abstractNote={Carbon nanotube (CNT) reinforced nanostructured Cu matrix composite with a grain size less than 25 nm has been successfully fabricated via a combination of ball milling and high-pressure torsion. CNTs were found to be homogeneously dispersed into the metal matrix, leading to grain refinement with a narrow grain size distribution and significant increase in hardness.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Li, Hongqi and Misra, Amit and Zhu, Yuntian and Horita, Zenji and Koch, Carl C. and Holesinger, Terry G.}, year={2009}, month={Oct}, pages={60–64} }
 @article{beyerlein_porwal_zhu_hu_xu_2009, title={Scale and twist effects on the strength of nanostructured yarns and reinforced composites}, volume={20}, DOI={10.1088/0957-4484/20/48/485702}, abstractNote={In this work we investigate the effects of yarn diameter and gauge length on the statistical strength of yarns spun from carbon nanotubes (CNTs). Tensile tests are conducted on a large sample set of nanostructured CNT yarns. The data show that strength varies substantially and both strength and statistical dispersion in strength decreases as yarn diameter increases. To explain these phenomena and forecast their effects on larger-scale structures, a hierarchical set of Monte Carlo simulation models is developed: the lower-scale model aims to predict the relationship between yarn nanostructure and tensile strength and the higher-scale model aims to relate the strength of CNT yarns to the strength of composites reinforced with unidirectionally aligned CNT yarns. Predictions indicate that, for both structures, the mean and statistical variation in strength will decrease as the surface twist angle, number of CNTs in cross section and gauge length of the yarn increases. The predicted reductions in variability due to yarn nanostructure will be important for determining ways to minimize the detrimental effects of increasing length scale on strength.}, number={48}, journal={NANOTECHNOLOGY}, author={BEYERLEIN, IJ and PORWAL, PK and Zhu, Y.T. and HU, K and XU, XF}, year={2009} }
 @article{valiev_langdon_alexandrov_zhu_estrin_kostorz_2009, title={Special Issue International Symposium on Bulk Nanostructured Materials: From Fundamentals to Innovation, BNM 2007 held at Ufa, Russia August 14-18, 2007 Preface}, volume={503}, number={1-2}, journal={Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing}, author={Valiev, R. Z. and Langdon, T. G. and Alexandrov, I. V. and Zhu, Y. T. and Estrin, Y. and Kostorz, G.}, year={2009}, pages={1–1} }
 @article{wu_zhu_wei_wei_2009, title={Strong Strain Hardening in Nanocrystalline Nickel}, volume={103}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.103.205504}, abstractNote={Low strain hardening has hitherto been considered an intrinsic behavior for most nanocrystalline (NC) metals, due to their perceived inability to accumulate dislocations. In this Letter, we show strong strain hardening in NC nickel with a grain size of approximately 20 nm under large plastic strains. Contrary to common belief, we have observed significant dislocation accumulation in the grain interior. This is enabled primarily by Lomer-Cottrell locks, which pin the lock-forming dislocations and obstruct dislocation motion. These observations may help with developing strong and ductile NC metals and alloys.}, number={20}, journal={PHYSICAL REVIEW LETTERS}, author={Wu, X. L. and Zhu, Y. T. and Wei, Y. G. and Wei, Q.}, year={2009}, month={Nov} }
 @article{li_misra_horita_koch_mara_dickerson_zhu_2009, title={Strong and ductile nanostructured Cu-carbon nanotube composite}, volume={95}, ISSN={["1077-3118"]}, DOI={10.1063/1.3211921}, abstractNote={Nanocrystalline carbon nanotube (CNT)—reinforced Cu composite (grain size <25 nm) with high strength and good ductility was developed. Pillar testing reveals that its strength and plastic strain could be as large as 1700 MPa and 29%, respectively. Compared with its counterpart made under the same condition, an addition of 1 wt % CNTs leads to a dramatic increase in strength, stiffness and toughness without a sacrifice in ductility. Microstructural analysis discloses that in the Cu matrix, CNTs could be distributed either at grain boundaries or inside grains and could inhibit dislocation nucleation and motion, resulting in an increase in the strength.}, number={7}, journal={APPLIED PHYSICS LETTERS}, author={Li, Hongqi and Misra, Amit and Horita, Zenji and Koch, Carl C. and Mara, Nathan A. and Dickerson, Patricia O. and Zhu, Yuntian}, year={2009}, month={Aug} }
 @article{zhang_zou_doorn_htoon_stan_hawley_sheehan_zhu_jia_2009, title={Tailoring the Morphology of Carbon Nanotube Arrays: From Spinnable Forests to Undulating Foams}, volume={3}, ISSN={["1936-086X"]}, DOI={10.1021/nn9003988}, abstractNote={Directly spinning carbon nanotube (CNT) fibers from vertically aligned CNT arrays is a promising way for the application of CNTs in the field of high-performance materials. However, most of the reported CNT arrays are not spinnable. In this work, by controlling catalyst pretreatment conditions, we demonstrate that the degree of spinnability of CNTs is closely related to the morphology of CNT arrays. Shortest catalyst pretreatment time led to CNT arrays with the best spinnability, while prolonged pretreatment resulted in coarsening of catalyst particles and nonspinnable CNTs. By controlling the coalescence of catalyst particles, we further demonstrate the growth of undulating CNT arrays with uniform and tunable waviness. The CNT arrays can be tuned from well-aligned, spinnable forests to uniformly wavy, foam-like films. To the best of our knowledge, this is the first systematical study on the correlation between catalyst pretreatment, CNT morphology, and CNT spinnability.}, number={8}, journal={ACS NANO}, author={Zhang, Yingying and Zou, Guifu and Doorn, Stephen K. and Htoon, Han and Stan, Liliana and Hawley, Marilyn E. and Sheehan, Chris J. and Zhu, Yuntian and Jia, Quanxi}, year={2009}, month={Aug}, pages={2157–2162} }
 @article{zhu_wu_liao_narayan_mathaudhu_kecskés_2009, title={Twinning partial multiplication at grain boundary in nanocrystalline fcc metals}, volume={95}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.3187539}, DOI={10.1063/1.3187539}, abstractNote={Most deformation twins in nanocrystalline face-centered cubic (fcc) metals have been observed to form from grain boundaries. The growth of such twins requires the emission of Shockley partials from the grain boundary on successive slip planes. However, it is statistically improbable for a partial to exist on every slip plane. Here we propose a dislocation reaction and cross-slip mechanism on the grain boundary that would supply a partial on every successive slip plane for twin growth. This mechanism can also produce a twin with macrostrain smaller than that caused by a conventional twin.}, number={3}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Zhu, Y. T. and Wu, X. L. and Liao, X. Z. and Narayan, J. and Mathaudhu, S. N. and Kecskés, L. J.}, year={2009}, month={Jul}, pages={031909} }
 @article{peng_jain_peterson_zhu_jia_2008, title={Composite Carbon Nanotube/Silica Fibers with Improved Mechanical Strengths and Electrical Conductivities}, volume={4}, ISSN={["1613-6829"]}, DOI={10.1002/smll.200800231}, abstractNote={Carbon nanotube (CNT)/silica composites have been extensively investigated due to their superior combined properties, which come from both CNTs and silica. For example, CNTs impart good mechanical, electrical, and chemical performance to the composites, while silica makes the composites stable in harsh environments (such as high temperatures and strong acids/bases) and easy to fabricate. A combined set of desired properties for CNT/silica composites cannot be found in their individual constituents, thusmaking these compositematerials very useful in many applications. To synergistically utilize their excellent properties, CNT/silica composites with various morphologies, including films synthesized by solution casting, powders by hot pressure, xerogels by sol-gel technique, and nanocomposite films or powders by covalent connection between CNTs and silica, have been widely studied. One of the main challenges for the manufacture of these materials is the random dispersion of CNTs in the resulting composites, which leads to much reducedmechanical and electrical properties. For example, CNT/silica composites with up to 30 vol% CNT processed by hot pressing show a maximum mechanical stress of only 85MPa. Here, we report the first synthesis of composite CNT/silica fibers in which the CNTs are highly aligned. These composite fibers show much improved mechanical properties and electrical conductivities compared with CNT/silica films, powders, or xerogels. The CNT/silica fibers show good tensile strengths due to the formation of robust and strong cross-}, number={11}, journal={SMALL}, author={Peng, Huisheng and Jain, Menka and Peterson, Dean E. and Zhu, Yuntian and Jia, Quanxi}, year={2008}, month={Nov}, pages={1964–1967} }
 @article{wu_narayan_zhu_2008, title={Deformation twin formed by self-thickening, cross-slip mechanism in nanocrystalline Ni}, volume={93}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2949685}, DOI={10.1063/1.2949685}, abstractNote={We report the observation of a deformation twin formed by a recently proposed self-thickening, cross-slip twinning mechanism. This observation verifies one more twinning mechanism, in addition to those reported before, in nanocrystalline face-centered-cubic metals. In this mechanism, once the first Shockley partial is emitted from a grain boundary, and cross slips onto another slip plane, a deformation twin could nucleate and grow in both the primary and cross-slip planes without requiring the nucleation of additional Shockley partials from the grain boundary.}, number={3}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Wu, X. L. and Narayan, J. and Zhu, Y. T.}, year={2008}, month={Jul}, pages={031910} }
 @article{zhu_liao_wu_2008, title={Deformation twinning in bulk nanocrystalline metals: Experimental observations}, volume={60}, ISSN={["1543-1851"]}, DOI={10.1007/s11837-008-0120-1}, abstractNote={Deformation twins have been observed in nanocrystalline (nc) fcc metals with medium-to-high stacking fault energies such as aluminum, copper, and nickel. These metals in their coarse-grained states rarely deform by twining at room temperature and low strain rates. Several twinning mechanisms have been reported that are unique to nc metals. This paper reviews experimental evidences on deformation twinning and partial dislocation emissions from grain boundaries, twinning mechanisms, and twins with zero-macro-strain. Factors that affect the twinning propensity and recent analytical models on the critical grain sizes for twinning are also discussed. The current issues on deformation twinning in nanocrystalline metals are listed.}, number={9}, journal={JOM}, author={Zhu, Y. T. and Liao, X. Z. and Wu, X. L.}, year={2008}, month={Sep}, pages={60–64} }
 @inproceedings{zhao_liao_horita_langdon_zhu_2008, title={Determining the optimal stacking fault energy for achieving high ductility in ultrafine-grained Cu-Zn alloys}, volume={493}, number={1-2}, booktitle={Materials Science & Engineering. A, Structural Materials: Properties, Microstructure and Processing}, author={Zhao, Y. H. and Liao, X. Z. and Horita, Z. and Langdon, T. G. and Zhu, Y. T.}, year={2008}, pages={123–129} }
 @article{cheng_choo_zhao_al._2008, title={High ductility of ultrafine-grained steel via phase transformation}, volume={23}, DOI={10.1557/JMR.2008.0213}, abstractNote={There is often a tradeoff between strength and ductility, and the low ductility of ultrafine-grained (UFG) materials has been a major obstacle to their practical structural applications despite their high strength. In this study, we have achieved a ∼40% tensile ductility while increasing the yield strength of FeCrNiMn steel by an order of magnitude via grain refinement and deformation-induced martensitic phase transformation. The strain-rate effect on the inhomogeneous deformation behavior and phase transformation was studied in detail.}, number={6}, journal={JOURNAL OF MATERIALS RESEARCH}, author={CHENG, S and CHOO, H and ZHAO, YH and al.}, year={2008}, pages={1578–1586} }
 @article{zhao_topping_bingert_thornton_dangelewicz_li_liu_zhu_zhou_lavernia_et al._2008, title={High tensile ductility and strength in bulk nanostructured nickel}, volume={20}, ISSN={["1521-4095"]}, DOI={10.1002/adma.200800214}, abstractNote={In this Communication, we use cryomillingand subsequently quasi-isostatic (QI) forging processes(formerly known as Ceracon forging), to prepare bulk densemultimodalandbimodalNSNiwithtensileductilityof42%and49%,andyieldstrengthsof457and312MPa,respectively.Thiscombinationofstrengthandductilityismuchsuperiortothoseofthe NS Ni prepared by electro-deposition (ED),}, number={16}, journal={ADVANCED MATERIALS}, author={Zhao, Y. H. and Topping, T. and Bingert, J. F. and Thornton, J. J. and Dangelewicz, A. M. and Li, Y. and Liu, W. and Zhu, Y. T. and Zhou, Y. Z. and Lavernia, E. L. and et al.}, year={2008}, month={Aug}, pages={3028–3033} }
 @article{zhao_topping_bingert_al._2008, title={High tensile ductility and strength in bulk nanostructured nickel}, volume={20}, number={16}, journal={ADVANCED MATERIALS}, author={ZHAO, YH and TOPPING, T and BINGERT, JF and al.}, year={2008}, pages={3028–3033} }
 @article{zhao_guo_wei_dangelewiez_zhu_langdon_zhou_lavernia_xu_2008, title={Influence of specimen dimensions on the tensile behavior of ultrafine-grained Cu}, volume={59}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2008.05.031}, abstractNote={Miniature dog-bone specimens with different sizes and geometries are frequently used to measure the tensile behaviors of nanostructured materials. Here we report a significant specimen dimensions influence on the tensile behavior of ultrafine-grained Cu: the elongation to failure, post-necking elongation and strain hardening rate all increase with increasing thickness or decreasing gauge length. The thickness effect is caused by the necking geometry and the effect of gauge length originates from the strain definition.}, number={6}, journal={SCRIPTA MATERIALIA}, author={Zhao, Y. H. and Guo, Y. Z. and Wei, Q. and Dangelewiez, A. M. and Zhu, Y. T. and Langdon, T. G. and Zhou, Y. Z. and Lavernia, E. J. and Xu, C.}, year={2008}, month={Sep}, pages={627–630} }
 @article{wang_wang_liao_zhao_lavernia_zhu_horita_langdon_2009, title={Influence of stacking fault energy on deformation mechanism and dislocation storage capacity in ultrafine-grained materials}, volume={60}, ISSN={["1359-6462"]}, DOI={10.1016/j.scriptamat.2008.08.032}, abstractNote={Partial dislocation emission from grain boundaries in metals with medium-to-high stacking fault energies is observed primarily in the grain size range of a few tens of nanometers. Here we report that a reduction in the stacking fault energy permits the emission of partial dislocations from grain boundaries in ultrafine-grained materials with grain sizes significantly larger than 100 nm and this produces twinning. Such twins are effective in increasing the dislocation storage capacity, which may be used to improve the ductility.}, number={1}, journal={SCRIPTA MATERIALIA}, author={Wang, Z. W. and Wang, Y. B. and Liao, X. Z. and Zhao, Y. H. and Lavernia, E. J. and Zhu, Y. T. and Horita, Z. and Langdon, T. G.}, year={2009}, month={Jan}, pages={52–55} }
 @article{balogh_ungar_zhao_al._2008, title={Influence of stacking-fault energy on microstructural characteristics of ultrafine-grain copper and copper-zinc alloys}, volume={56}, DOI={10.1016/j.actamat.2007.10.053}, abstractNote={Experiments were conducted on samples of pure Cu and two Cu–Zn alloys to evaluate the influence of the stacking-fault energy (SFE) on microstructural development when processing using high-pressure torsion (HPT). Transmission electron microscopy, X-ray diffraction and hardness measurements were used for microstructural evaluation and the results show consistency between these techniques. Grain sizes in the nanometer range were formed at the edges of the HPT disks, larger submicrometer grains were formed in the disk centers and the measured grain sizes decreased with decreasing SFE. There was negligible twinning in pure Cu but the densities of dislocations and twins increased with increasing Zn content and thus with decreasing SFE. The values of the Vickers microhardness were lower in the centers of the disks for the two Cu–Zn alloy and this is consistent with the low SFE and slow rates of recovery.}, number={4}, journal={ACTA MATERIALIA}, author={BALOGH, L and UNGAR, T and ZHAO, Y and al.}, year={2008}, pages={809–820} }
 @article{wu_zhu_2008, title={Inverse grain-size effect on twinning in nanocrystalline Ni}, volume={101}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.101.025503}, abstractNote={A long-standing controversy exists between molecular dynamics simulations and experiments on the twinning propensity of nanocrystalline (NC) face-centered-cubic metals. For example, three-dimensional molecular dynamics simulations rarely observed twins in NC Ni, whereas experiments readily observed them. Here this discrepancy is resolved by experimental observation of an inverse grain-size effect on twinning. Specifically, decreasing the grain size first promotes twinning in NC Ni and then hinders twinning due to the inverse grain-size effect. Interestingly, no inverse grain-size effect exists on stacking fault formation. These observations are explained by generalized planar fault energies and grain-size effect on partial emissions.}, number={2}, journal={PHYSICAL REVIEW LETTERS}, author={Wu, X. L. and Zhu, Y. T.}, year={2008}, month={Jul} }
 @inbook{raaba_valiev_gunderov_lowe_misra_zhu_2008, title={Long-length ultrafine-grained titanium rods produced by ECAP-Conform}, volume={584-586}, booktitle={Nanomaterials By Severe Plastic Deformation Iv, Pts 1 and 2}, author={Raaba, GI and Valiev, RZ and Gunderov, DV and Lowe, TC and Misra, A and Zhu, YT}, year={2008}, pages={80–85} }
 @article{zhang_kostorz_liu_rigsbee_suryanarayana_wang_zhu_zhang_2008, title={Mechanical Behavior of Nanostructured Materials, in Honor of Carl Koch held at TMS 2007, Orlando, Florida Preface}, volume={493}, ISSN={["0921-5093"]}, DOI={10.1016/j.msea.2008.01.019}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={Zhang, Xinghang and Kostorz, Gernot and Liu, Chain T. and Rigsbee, Mike and Suryanarayana, C. and Wang, Haiyan and Zhu, Yuntian and Zhang, Deliang}, year={2008}, month={Oct}, pages={1–2} }
 @article{peng_zhu_peterson_al._2008, title={Nanolayeired carbon/silica superstructures via organosilane assembly}, volume={20}, DOI={10.1002/adma.200701303}, abstractNote={Figure1ashowsthefirstsyntheticapproachusingsilicananoparticles in two steps, i.e., mixture of silica nanoparticlesand carbon precursors followed by carbonization of the intro-duced precursor at high temperatures. For this synthesis, theprocess is easy to operate and control, and the efficiency istypically high. However, the composites are not uniform; car-bonizationmainlyproducesamorphouscarbon;bothsilicaandcarbon are not highly ordered; and it is difficult to tune thecomposite morphologies (normally films or powders, depend-ing on the synthetic process). The second approach requiresmore complex operations (Fig. 1b): 1) formation of silica/surfactant nanocomposite materials by co-assembly of silicatesand surfactants; 2) removal of surfactants by extraction orcalcination; 3) incorporation of carbon precursors into thepores of the mesoporous silica materials; 4) carbonization ofthe carbonprecursors at high temperatures. Amainadvantageusingmesoporoussilicaistosynthesizecarbon/silicacompositematerials with tunable mesostructures (lamellar, hexagonal, orcubic, depending on the used surfactants) and uniform compo-sitions in the nano-scale. The limitations for the second fabri-cation include tedious procedures, production of amorphouscarbon materials after carbonization, and uncontrolledmorphologies of composite materials.To summarize, the synthesized materials from above ap-proaches show two common disadvantages. First, the carbon/silica composites are not conducting due to the formation ofamorphous carbon, and they do not demonstrate good func-tionalities for potential applications in themselves. Therefore,the main focus is to remove silica using HF to produce porouscarbon, which may be applied in water and air purification,separation, catalysis, and energy storage.}, number={6}, journal={ADVANCED MATERIALS}, author={PENG, HS and ZHU, YT and PETERSON, DE and al.}, year={2008}, pages={1199-+} }
 @article{wu_liao_srinivasan_al._2008, title={New deformation twinning mechanism generates zero macroscopic strain in nanocrystalline metals}, volume={1}, DOI={10.1103/PhysRevLett.100.095701}, abstractNote={Macroscopic strain was hitherto considered a necessary corollary of deformation twinning in coarse-grained metals. Recently, twinning has been found to be a preeminent deformation mechanism in nanocrystalline face-centered-cubic (fcc) metals with medium-to-high stacking fault energies. Here we report a surprising discovery that the vast majority of deformation twins in nanocrystalline Al, Ni, and Cu, contrary to popular belief, yield zero net macroscopic strain. We propose a new twinning mechanism, random activation of partials, to explain this unusual phenomenon. The random activation of partials mechanism appears to be the most plausible mechanism and may be unique to nanocrystalline fcc metals with implications for their deformation behavior and mechanical properties.}, number={9}, journal={PHYSICAL REVIEW LETTERS}, author={WU, XL and LIAO, XZ and SRINIVASAN, SG and al.}, year={2008} }
 @article{wu_liao_srinivasan_zhou_lavernia_valiev_zhu_2008, title={New deformation twinning mechanism generates zero macroscopic strain in nanocrystalline metals}, volume={1}, number={9}, journal={Physical Review Letters}, author={Wu, X. L. and Liao, X. Z. and Srinivasan, S. G. and Zhou, F. and Lavernia, E. J. and Valiev, R. Z. and Zhu, Y. T.}, year={2008} }
 @article{valiev_langdon_alexandrov_zhu_estrin_kostorz_2009, title={Preface}, volume={503}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2008.11.027}, DOI={10.1016/j.msea.2008.11.027}, abstractNote={Severe plastic deformation is one of the methods widely used for producing a fine-grained structure throughout the volume. Different SPD methods have been used for producing a fine-grained and ultra-fine grained structure which effectively alters the microstructure and in turn improve the properties. This paper deals with the different methods, process of SPD techniques for producing nanograin structure for different alloys and factors that impact on the change in the nature of microstructure}, number={1-2}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Valiev, Ruslan Z. and Langdon, Terence G. and Alexandrov, Igor V. and Zhu, Yuntian T. and Estrin, Yuri and Kostorz, Gernot}, year={2009}, month={Mar}, pages={1} }
 @article{zhu_estrin_langdon_liao_lowe_shan_valiev_2008, title={Preface}, volume={43}, ISSN={0022-2461 1573-4803}, url={http://dx.doi.org/10.1007/s10853-008-2991-5}, DOI={10.1007/s10853-008-2991-5}, number={23-24}, journal={Journal of Materials Science}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian and Estrin, Yuri and Langdon, Terence G. and Liao, Xiaozhou and Lowe, Terry C. and Shan, Zhiwei and Valiev, Ruslan Z.}, year={2008}, month={Dec}, pages={7255–7256} }
 @article{narayan_zhu_2008, title={Self-thickening, cross-slip deformation twinning model}, volume={92}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2911735}, DOI={10.1063/1.2911735}, abstractNote={We propose a cross-slip deformation twinning model based upon our experimental in situ deformation of Cu–Ge alloys using a transmission electron microscope. During the deformation, Shockley partials are emitted from the grain boundaries, which encounter an obstacle within the grain and split to nucleate deformation twins in the cross slip as well as primary planes. Upon further deformation a thickening process for twins is directly observed. The proposed model provides a dislocation mechanism for the observed simultaneous twin thickening in both the cross-slip and primary planes. The role of the proposed mechanism in the deformation of nanocrystalline materials is discussed.}, number={15}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Narayan, J. and Zhu, Y. T.}, year={2008}, month={Apr}, pages={151908} }
 @article{narayan_zhu_2008, title={Self-thickening, cross-slip deformation twinning model}, volume={92}, number={15}, journal={Applied Physics Letters}, author={Narayan, J. and Zhu, Y. T.}, year={2008} }
 @article{zhu_estrin_langdon_liao_lowe_shan_valiev_2008, title={Special issue: Ultrafine-grained materials preface}, volume={43}, number={23-24}, journal={Journal of Materials Science}, author={Zhu, Y. T. and Estrin, Y. and Langdon, T. G. and Liao, X. Z. and Lowe, T. C. and Shan, Z. W. and Valiev, R. Z.}, year={2008}, pages={7255–7256} }
 @article{peng_chen_huang_chikkannanavar_haenisch_jain_peterson_doorn_lu_zhu_et al._2008, title={Strong and ductile colossal carbon tubes with walls of rectangular macropores}, volume={101}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.101.145501}, abstractNote={We report a new type of carbon material-porous colossal carbon tubes. Compared with carbon nanotubes, colossal carbon tubes have a much bigger size, with a diameter of between 40 and 100 mum and a length in the range of centimeters. Significantly, the walls of the colossal tubes are composed of macroscopic rectangular columnar pores and exhibit an ultralow density comparable to that of carbon nanofoams. The porous walls of colossal tubes also show a highly ordered lamellar structure similar to that of graphite. Furthermore, colossal tubes possess excellent mechanical and electrical properties.}, number={14}, journal={PHYSICAL REVIEW LETTERS}, author={Peng, Huisheng and Chen, Daoyong and Huang, Jian-Yu and Chikkannanavar, S. B. and Haenisch, J. and Jain, Menka and Peterson, D. E. and Doorn, S. K. and Lu, Yunfeng and Zhu, Y. T. and et al.}, year={2008}, month={Oct} }
 @article{zhao_bingert_zhu_al._2008, title={Tougher ultrafine grain Cu via high-angle grain boundaries and low dislocation density}, volume={92}, DOI={10.1063/1.2870014}, abstractNote={Although there are a few isolated examples of excellent strength and ductility in single-phase metals with ultrafine grained (UFG) structures, the precise role of different microstructural features responsible for these results is not fully understood. Here, we demonstrate that a large fraction of high-angle grain boundaries and a low dislocation density may significantly improve the toughness and uniform elongation of UFG Cu by increasing its strain-hardening rate without any concomitant sacrifice in its yield strength. Our study provides a strategy for synthesizing tough UFG materials.}, number={8}, journal={APPLIED PHYSICS LETTERS}, author={ZHAO, YH and BINGERT, JF and ZHU, YT and al.}, year={2008} }
 @article{peng_jain_li_peterson_zhu_jia_2008, title={Vertically aligned pearl-like carbon nanotube arrays for fiber spinning}, volume={130}, ISSN={["1520-5126"]}, DOI={10.1021/ja077767c}, abstractNote={This work reports the first synthesis of highly aligned, pearl-like carbon nanotube arrays through a chemical vapor deposition process. The unique morphology of these carbon nanotubes makes it possible to spin them into macroscopic fibers with excellent mechanical and electrical properties. In addition, the interesting hollow structure of these nanotubes opens new applications such as nanoreactors.}, number={4}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Peng, Huisheng and Jain, Menka and Li, Qingwen and Peterson, Dean E. and Zhu, Yuntian and Jia, Quanxi}, year={2008}, month={Jan}, pages={1130-+} }
 @article{wang_huang_jiao_al._2007, title={Abnormal strain hardening in nanostructured titanium at high strain rates and large strains}, volume={42}, number={5}, journal={JOURNAL OF MATERIALS SCIENCE}, author={WANG, YM and HUANG, JY and JIAO, T and al.}, year={2007}, pages={1751–1756} }
 @article{zheng_zhang_li_al._2007, title={Carbon-nanotube cotton for large-scale fibers}, volume={19}, DOI={10.1002/adma.200602648}, abstractNote={Carbon nanotubes (CNTs) are much stronger than any existing material. To fully utilize their extremely high strength, carbon-nanotubes must be spun into continuous fibers.}, number={18}, journal={ADVANCED MATERIALS}, author={ZHENG, LX and ZHANG, XF and LI, QW and al.}, year={2007}, pages={2567-+} }
 @article{wu_ma_zhu_2007, title={Deformation defects in nanocrystalline nickel}, volume={42}, ISSN={0022-2461 1573-4803}, url={http://dx.doi.org/10.1007/S10853-006-1229-7}, DOI={10.1007/S10853-006-1229-7}, abstractNote={Defects induced by plastic deformation in electrodeposited, fully dense nanocrystalline (nc) Ni with an average grain size of 25 nm have been characterized by means of high resolution transmission electron microscopy. The nc Ni was deformed under uniaxial tension at liquid-nitrogen temperature. Trapped full dislocations were observed in the grain interior and near the grain boundaries. In particular, these dislocations preferred to exist in the form of dipoles. Deformation twinning was confirmed in nc grains and the most proficient mechanism is the heterogeneous nucleation via emission of partial dislocations from the grain boundaries.}, number={5}, journal={Journal of Materials Science}, publisher={Springer Science and Business Media LLC}, author={Wu, Xiaolei and Ma, En and Zhu, Y. T.}, year={2007}, month={Jan}, pages={1427–1432} }
 @article{zhao_liao_horita_al._2008, title={Determining the optimal stacking fault energy for achieving high ductility in ultrafine-grained Cu-Zn alloys}, volume={493}, DOI={10.1016/j.msea.2007.11.074}, abstractNote={Bulk ultrafine-grained (UFG) materials produced by severe plastic deformation (SPD) often have low ductility. A previous study demonstrated the possibility of lowering the stacking fault energy to simultaneously increase the strength and ductility. This paper demonstrates, there exists an optimal stacking fault energy for the best ductility in UFG Cu–Zn alloys processed by the same SPD processing. When the stacking fault energy is too low, the grain size lies below 15 nm after SPD processing and the stacking faults are saturated so that it is difficult to accumulate dislocations and deformation twins during the subsequent tensile testing. These results provide significant guidance for the future design of UFG and nanocrystalline alloys for achieving high ductilities.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHAO, YH and LIAO, XZ and HORITA, Z and al.}, year={2008}, pages={123–129} }
 @article{zhao_horita_langdon_al._2008, title={Evolution of defect structures during cold rolling of ultrafine-grained Cu and Cu-Zn alloys: Influence of stacking fault energy}, volume={474}, DOI={10.1016/j.msea.2007.06.014}, abstractNote={Samples of pure Cu, bronze (Cu–10 wt.% Zn) and brass (Cu–30 wt.% Zn) with stacking fault energies (SFE) of 78, 35, and 14 mJ/m2, respectively, were processed by high-pressure torsion (HPT) and by a combination of HPT followed by cold-rolling (CR). X-ray diffraction measurements indicate that a decrease in SFE leads both to a decrease in crystallite size and to increases in microstrain, dislocation and twin densities for the HPT and HPT + CR processed ultrafine-grained (UFG) samples. Compared with processing by HPT, subsequent processing by CR refines the crystallite size of all samples, increases the twin densities of UFG bronze and brass, and increases the dislocation density in UFG bronze. It also decreases the dislocation density in UFG brass and leads to an unchanged dislocation density in UFG copper. The results suggest there may be an optimum stacking fault energy for dislocation accumulation in UFG Cu–Zn alloys and this has important implications in the production of materials having reasonable strain hardening and good tensile ductility.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHAO, YH and HORITA, Z and LANGDON, TG and al.}, year={2008}, pages={342–347} }
 @article{usov_wang_li_al._2007, title={Impurity elements study of carbon nanotubes fabricated by chemical vapor deposition}, volume={261}, DOI={10.1016/j.nimb.2007.04.173}, abstractNote={It is widely known that materials properties are very sensitive to the presence of impurity elements. In this study we performed Rutherford backscattering spectroscopy (RBS) and particle induced X-ray emission (PIXE) analysis of impurity elements in carbon nanotubes (CNTs) fabricated by chemical vapor deposition. Impurities such as O, Si, P, S, Cl, Ar, Ti, Cr and Fe were found. The O was uniformly distributed and the most abundant impurity in CNTs. Sources of contamination were investigated and it was suggested that the presence of Si, S, Cl, Ti and Cr can be eliminated.}, number={1-2}, journal={NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION B-BEAM INTERACTIONS WITH MATERIALS AND ATOMS}, author={USOV, IO and WANG, YQ and LI, Q and al.}, year={2007}, pages={574–577} }
 @article{zhao_zhu_liao_al._2007, title={Influence of stacking fault energy on the minimum grain size achieved in severe plastic deformation}, volume={463}, DOI={10.1016/j.msea.2006.08.119}, abstractNote={Samples of pure Cu and a Cu–10% Zn alloy were processed by high-pressure torsion and by high-pressure torsion followed by cold-rolling to a reduction of ∼75%. The grain sizes in these two conditions were measured by transmission electron microscopy and by X-ray diffraction. The experimental results show the average grain size and the width of the grain size distribution are both smaller in the Cu–10% Zn alloy by comparison with pure Cu. This difference is due to the lower stacking fault energy of the Cu–10% Zn alloy. An analysis shows all of the experimental results are consistent with a theoretical model predicting the minimum grain size produced by milling.}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHAO, YH and ZHU, YT and LIAO, XZ and al.}, year={2007}, pages={22–26} }
 @article{wang_tang_li_zheng_zhang_zheng_zhu_jin_yang_gu_2007, title={Length-dependent thermal conductivity of an individual single-wall carbon nanotube}, volume={91}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2779850}, DOI={10.1063/1.2779850}, abstractNote={The thermal conductivity of single-wall carbon nanotubes (SWCNTs) is predicted to increase with length, but this has never been proved experimentally because of limitations in previous measurement methods. Here, the authors report the measurement of the length-dependent thermal conductivities of individual SWCNTs on a Si substrate using a four-pad 3ω method. An increase in thermal conductivity with length was observed at room temperature, which is consistent with a theoretical prediction that considers higher order three-phonon processes. When SWCNTs are longer than the phonon mean path, they showed dissipative thermal transport. The observed increase of thermal conductivity with length makes SWCNTs ideal for thermal management.}, number={12}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Wang, Zhao Liang and Tang, Da Wei and Li, Xiao Bo and Zheng, Xing Hua and Zhang, Wei Gang and Zheng, Li Xin and Zhu, Yuntian T. and Jin, Ai Zi and Yang, Hai Fang and Gu, Chang Zhi}, year={2007}, month={Sep}, pages={123119} }
 @article{wang_tang_li_al._2007, title={Length-dependent thermal conductivity of an individual single-wall carbon nanotube}, volume={91}, journal={APPLIED PHYSICS LETTERS}, author={WANG, ZL and TANG, DW and LI, XB and al.}, year={2007} }
 @article{wang_tang_zheng_al._2007, title={Length-dependent thermal conductivity of single-wall carbon nanotubes: prediction and measurements}, volume={18}, DOI={10.1088/0957-4484/18/47/475714}, abstractNote={In this paper, we propose a modified wavevector (WV) model that takes account of the N-process relaxation time and second-order three-phonon process to predict the length dependence of the thermal conductivity of single-wall carbon nanotubes (SWNTs). The model is validated by length-dependent thermal conductivities of individual SWNTs measured using the four-pad 3ω method. The fitted Grüneisen parameter is close to 2 for SWNTs. These results indicate that the effect of the second-order three-phonon process cannot be neglected at room temperature. Both the experimental and theoretical results prove that the thermal conductivity increases with length of SWNTs over the range of 0.5–7 µm.}, number={47}, journal={NANOTECHNOLOGY}, author={WANG, ZL and TANG, DW and ZHENG, XH and al.}, year={2007} }
 @article{zhang_zhu_rigsbee_suryanarayana_wang_liu_2007, title={Mechanical Behavior of nanostructured materials symposium honoring Carl Koch}, volume={59}, ISSN={["1047-4838"]}, DOI={10.1007/s11837-007-0116-2}, number={9}, journal={JOM}, author={Zhang, Xinghang and Zhu, Yuntian and Rigsbee, Mike and Suryanarayana, C. and Wang, Haiyan and Liu, C. T.}, year={2007}, month={Sep}, pages={49–49} }
 @article{valiev_gunderov_prokofiev_pushin_zhu_2008, title={Nanostructuring of TiNi alloy by SPD processing for advanced properties}, volume={49}, ISSN={["1347-5320"]}, DOI={10.2320/matertrans.ME200722}, abstractNote={Ultrafine-grained (UFG) alloy Ti49:4Ni50:6 possessing both nano- as well as submicrocrystalline structure has been successfully produced using two techniques of severe plastic deformation (SPD) processing: high pressure torsion and equal channel angular pressing. The features of microstructure, martensitic transformation and deformation behavior of the UFG alloy have been studied in details. The effects of grain size on the mechanical and functional properties of the alloy are discussed. (doi:10.2320/matertrans.ME200722) TiNi alloys are well-known thanks to their remarkable properties-enhanced strength, corrosion resistance, and especially superelasticity and shape-memory effect. Due to this, they are very promising for many structural and functional applications in engineering and medicine. 1-3) Superelasticity and shape-memory effect of TiNi alloys are associated with martensitic transformations (MT) of the austenite phase B2 into the martensite phase B19 0 . These two extraordinary properties have been the object of numerous fundamental investigations. At the same time, for various advanced applications superior properties of TiNi would be very desirable, since they are required for miniaturization of articles and enhancement of their functional characteristics. Recent investigations testify that an effective way to enhance the properties of various metals and alloys is their nano- structuring using severe plastic deformation (SPD) process- ing. 4-6) During last years in our laboratories a number of investigations have been performed, dealing with nano- structuring of TiNi alloys, 7-11) using two most popular SPD techniques-high-pressure torsion (HPT) and equal-channel angular pressing (ECAP), and with the effect of the formed nanostructure on the deformation behaviour of alloys and martensitic transformations. This paper reports the results of the investigations of mechanical and functional properties of the Ti49:4Ni50:6 alloy that has an ultrafine-grained structure in the nano- and submicrocrystalline ranges. 2. Experimental Procedure}, number={1}, journal={MATERIALS TRANSACTIONS}, author={Valiev, Ruslan and Gunderov, Dmitry and Prokofiev, Egor and Pushin, Vladimir and Zhu, Yuntian}, year={2008}, month={Jan}, pages={97–101} }
 @article{cheng_zhao_zhu_al._2007, title={Optimizing the strength and ductility of fine structured 2024 Al alloy by nano-precipitation}, volume={55}, DOI={10.1016/j.actamat.2007.06.043}, abstractNote={Alloys with grain or subgrain structures refined down to 1 μm or below usually have high strength, but often inadequate tensile ductility. Past efforts in improving their ductility have usually led to a sacrifice of strength. We have developed an effective approach in achieving both high strength and high ductility in a 2024 Al alloy. The approach involves solution-treatment to partially dissolve T-phase particles, cryo-rolling to produce a fine-structure containing a high density of dislocations and submicrometer subgrains and aging to generate highly dispersed nano-precipitates. It was found that the remnant T-phase particles made it very effective in accumulating dislocations during cryo-rolling, which in turn promoted the precipitation of nanosized S′ precipitates with an interparticle spacing of only 10–20 nm. Such a high density of S′ precipitates enabled effective dislocation pinning and accumulation, leading to simultaneous increases in strength, work-hardening ability and ductility.}, number={17}, journal={ACTA MATERIALIA}, author={CHENG, S and ZHAO, YH and ZHU, YT and al.}, year={2007}, pages={5822–5832} }
 @article{wu_qi_zhu_2007, title={Partial-mediated slips in nanocrystalline Ni at high strain rate}, volume={90}, DOI={10.1063/1.2745250}, abstractNote={Previous experiments on nanocrystalline Ni were conducted under quasistatic strain rates (∼3×10−3∕s), which are much lower than that used in typical molecular dynamics simulations (>3×107∕s), thus making direct comparison of modeling and experiments very difficult. In this study, the split Hopkinson bar tests revealed that nanocrystalline Ni prefers twinning to extended partials, especially under higher strain rates (103∕s). These observations contradict some reported molecular dynamics simulation results, where only extended partials, but no twins, were observed. The accuracy of the generalized planar fault energies is only partially responsible, but cannot fully account for such a difference.}, number={22}, journal={APPLIED PHYSICS LETTERS}, author={WU, XL and QI, Y and ZHU, YT}, year={2007} }
 @article{zhu_wang_langdon_2007, title={Preface}, volume={42}, ISSN={0022-2461 1573-4803}, url={http://dx.doi.org/10.1007/S10853-006-1292-0}, DOI={10.1007/S10853-006-1292-0}, number={5}, journal={Journal of Materials Science}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian T. and Wang, Zhong Lin and Langdon, Terence G.}, year={2007}, month={Jan}, pages={1401–1402} }
 @article{zhang_li_tu_li_coulter_zheng_zhao_jia_peterson_zhu_2007, title={Strong Carbon-Nanotube Fibers Spun from Long Carbon-Nanotube Arrays}, volume={3}, ISSN={1613-6810 1613-6829}, url={http://dx.doi.org/10.1002/smll.200600368}, DOI={10.1002/smll.200600368}, abstractNote={The superior mechanical properties of carbon nanotubes (CNTs) mean they have been regarded as a new material with the potential to revolutionize and enable many advanced technologies. CNTs have extremely high tensile strength ( 150 GPa), high modulus ( 1 TPa), large aspect ratio, low density, good chemical and environmental stability, and high thermal and electrical conductivity. These superior and unique properties make CNTs very attractive for many structural applications such as aerospace structures, body armors, and sporting goods. Early studies of CNT-reinforced nanocomposites showed that CNTs were effective fillers to enhance the mechanical properties of polymer matrices, but the reinforcement was limited by the quality of dispersion, CNT alignment, and load-transfer efficiency between the CNT and the matrix. The full reinforcement potential of CNTs has not yet been utilized in CNT composites. It has been a challenge to make macroscale CNT structures and to fully utilize the outstanding mechanical properties of CNTs. The first macroscale CNT structure was in the form of a film called buckypaper, which displayed relatively high electrical and thermal conductivity, but low mechanical properties. For the purpose of obtaining superior mechanical performance, researchers have recently focused on CNT fibers. The first CNT fiber was successfully prepared through spinning a CNT homogeneous dispersion into a polyvinyl alcohol (PVA) coagulation bath. This approach was modified by Baughman s group to make single-walled (SW) CNT composite fibers with very high strength. 8] The major issues with this approach include a relatively high fraction of remaining polymer volume and short individual CNTs, which limits the fiber s strength, electrical and thermal conductivity. Recently, new approaches have been reported in which pure CNT fibers were spun without a matrix. For example, pure CNT fibers were spun from a CNT-fuming sulfuric acid solution. A continuous multi-walled (MW) CNT yarn was pulled from a high-quality array without twisting. SWCNT fibers were spun from an aerogel in the chemical vapor deposition synthesis zone, and MWCNT fibers were spun from CNT arrays. 15] These CNT fibers usually have a strength of 1.5 GPa and a Young s modulus of 30 GPa. Here, we report the spinning of CNT fibers from relatively long CNT arrays (0.65 mm). The influence of post-spin twisting on the mechanical performance of these fibers is also discussed. Figure 1a shows a scanning electron microscopy (SEM) image of the 0.65-mm CNT array, which is synthesized by}, number={2}, journal={Small}, publisher={Wiley}, author={Zhang, Xiefei and Li, Qingwen and Tu, Yi and Li, Yuan and Coulter, James Y. and Zheng, Lianxi and Zhao, Yonghao and Jia, Qianxi and Peterson, Dean E. and Zhu, Yuntian}, year={2007}, month={Feb}, pages={244–248} }
 @article{zhang_li_tu_al._2007, title={Strong carbon-nanotube fibers spun from long carbon-nanotube arrays}, volume={3}, number={2}, journal={SMALL}, author={ZHANG, XF and LI, QW and TU, Y and al.}, year={2007}, pages={244–248} }
 @article{li_li_zhang_al._2007, title={Structure-dependent electrical properties of carbon nanotube fibers}, volume={19}, DOI={10.1002/adma.200602966}, abstractNote={Spun carbon nanotube (CNT) fibers have great potential for conducting and sensing applications owing to their unique, tunable electrical properties. Here we report the electron transport properties of neat, well-aligned CNT fibers spun from arrays of millimeter-long CNTs. The conductivity of asspun CNT fibers is around 595.2 S cm at room temperature, and its variation with temperature shows a semiconductive behavior from 300 to 75.4 K. The electron transport was found to follow a three-dimensional (3D) hopping mechanism. Importantly, it was found that chemical treatments may significantly affect the conductivities of as-spun fibers. Oxidizing the CNT fibers in air or HNO3 increased the conductivities, while covalent bonding of Au nanoparticles to the CNT fibers remarkably improved conductivity and changed conduction behavior. Conversely, annealing CNT fibers in Ar+ 6% H2 at 800 °C or under the CNT array growth conditions at 750 °C led to a dramatic decrease in conductivity. Owing to their conjugated and highly anisotropic 1D structures, carbon nanotubes (CNTs) are a fascinating new class of electronic materials from both theoretical and applied standpoints. The excellent conductivities of CNTs and their ability to carry very high current density, along with their high thermal conductivity, chemical stability, and mechanical strength, make CNTs uniquely promising for a broad range of applications, including building blocks for nanoscale electronic devices, microsensors for bio-agents and chemicals, and power cables for space shuttles. The electrical resistivity q of individual CNTs has been measured under ballistic conductions to be as low as 10 X cm for single-walled and 3× 10 X cm for multiwalled CNTs, respectively, indicating that CNTs may be better conductors than metals such as copper at room temperature. However, in most cases, due to the presence of various defects or impurities formed during the CNT growth, the conductivities of individual CNTs are often much lower than those under ballistic conduction with nanotubes free of defects. The electron transport in CNT assemblies is different from that in individual nanotubes. It has been reported that singlewalled carbon nanotube (SWNT) fibers, either synthesized directly by vertical floating chemical vapor deposition (CVD) methods or extruded from a super-acid suspension, exhibit room-temperature resistivities in the range of 1 × 10 to 7 × 10 X cm, which is nearly 100 times higher than the resistivities of single nanotubes. The resistivities of multiwalled carbon nanotube (MWNT) fibers are typically one or two orders of magnitude higher than that of SWNT fibers. Such large differences between single nanotubes and fiber assemblies may arise from a high impurity content (such as amorphous carbon and catalytic particles) in the fibers, which may profoundly affect electron transport by causing significant scattering, and contact resistances between nanotubes. Therefore, two approaches can be used to improve the electrical conductivity of CNT fibers: 1) minimize the contact resistances between nanotubes by improving the alignment of CNTs and by increasing the lengths of individual tubes; 2) improve the conductivity of individual CNTs by post-synthesis treatments. Itwas the objective of the study reported here to use these two approaches to produce CNT fibers with high conductivity and to study the fundamental conduction mechanisms of the CNT fibers. Thin and clean CNT fibers (typically 3 lm in diameter) were spun from arrays of well-aligned, millimeter-long CNTs, which were synthesized using ethylene CVD on a Fe catalyst film. By measuring the resistance of CNT fibers at temperatures from 300 K to 75.4 K, we investigated the electronic properties of as-spun fibers and their possible conducting mechanisms. It was also found that the conductivity of CNT fibers could be tuned through mild post-treatments. The spun CNT fibers were post-treated with five different procedures: 1) Annealing in air at 480 °C for half an hour in an attempt to clean off the amorphous carbon, whose oxidation temperature is often around 400 °C. 2) Oxidizing in dilute 5 M HNO3 solution at 40 °C to cause a weak chemical C O M M U N IC A TI O N}, number={20}, journal={ADVANCED MATERIALS}, author={LI, QW and LI, Y and ZHANG, XF and al.}, year={2007}, pages={3358-+} }
 @article{yao_li_zhang_al._2007, title={Temperature-mediated growth of single-walled carbon-nanotube intramolecular junctions}, volume={6}, DOI={10.1038/nmat1865}, abstractNote={Single-walled carbon nanotubes (SWNTs) possess superior electronic and physical properties that make them ideal candidates for making next-generation electronic circuits that break the size limitation of current silicon-based technology. The first critical step in making a full SWNT electronic circuit is to make SWNT intramolecular junctions in a controlled manner. Although SWNT intramolecular junctions have been grown by several methods, they only grew inadvertently in most cases. Here, we report well-controlled temperature-mediated growth of intramolecular junctions in SWNTs. Specifically, by changing the temperature during growth, we found that SWNTs systematically form intramolecular junctions. This was achieved by a consistent variation in the SWNT diameter and chirality with changing growth temperature even though the catalyst particles remained the same. These findings provide a potential approach for growing SWNT intramolecular junctions at desired locations, sizes and orientations, which are important for making SWNT electronic circuits.}, number={4}, journal={NATURE MATERIALS}, author={YAO, YG and LI, QW and ZHANG, J and al.}, year={2007}, pages={283–286} }
 @article{zhang_li_holesinger_arendt_huang_kirven_clapp_depaula_liao_zhao_et al._2007, title={Ultrastrong, stiff, and lightweight carbon-nanotube fibers}, volume={19}, ISSN={["1521-4095"]}, DOI={10.1002/adma.200700776}, abstractNote={From the stone ages to modern history, new materials have often been the enablers of revolutionary technologies. [1] For a wide variety of envisioned applications in space exploration, energy-efficient aircraft, and armor, materials must be significantly stronger, stiffer, and lighter than what is currently available. Carbon nanotubes (CNTs) have extremely high strength, [2–5] very high stiffness, [6,7] low density, good chemical stability, and high thermal and electrical conductivities. [8] These superior properties make CNTs very attractive for many structural applications and technologies. Here we report CNT fibers that are many times stronger and stiffer per weight than the best existing engineering fibers and over twenty times better than other reported CNT fibers. Additionally, our CNT fibers are nonbrittle and tough, making them far superior to existing materials for preventing catastrophic failure. These new CNT fibers will not only make tens of thousands of products stronger, lighter, safer, and more energy efficient, but they will also bring to fruition many envisioned technologies that have been to date unavailable because of material restrictions. Strong, stiff, and lightweight are critical property requirements for materials that are used in the construction of space shuttles, airplanes, and space structures. These properties are assessed by a material’s specific strength and specific stiffness, which are defined as the strength or stiffness (Young’s modulus) of a material divided by its density. [9] The combination of high strength, high stiffness, and low density affords CNTs with extremely high values for specific strength and specific stiffness. The most effective way to utilize these properties is to assemble CNTs into fibers. However, despite extensive worldwide efforts to date, the specific strength and specific stiffness of CNT fibers that have been reported by various research groups are much lower than currently available commercial fibers. [10–22] In early studies, researchers attempted to reinforce polymer fibers with short CNTs, but the reinforcement was limited by several issues, including poor dispersion, poor alignment, poor load transfer, and a low CNT volume fraction. [10–15] Recently, pure CNT fibers (also called yarns) were reported with and without twisting. [16–22] For example, Zhang et al. [20] demonstrated that spinning from aligned CNT}, number={23}, journal={ADVANCED MATERIALS}, author={Zhang, Xiefei and Li, Qingwen and Holesinger, Terry G. and Arendt, Paul N. and Huang, Jianyu and Kirven, P. Douglas and Clapp, Timothy G. and DePaula, Raymond F. and Liao, Xiazhou and Zhao, Yonghao and et al.}, year={2007}, month={Dec}, pages={4198-+} }
 @article{ungar_balogh_zhu_al._2007, title={Using X-ray microdiffraction to determine grain sizes at selected positions in disks processed by high-pressure torsion}, volume={444}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={UNGAR, T and BALOGH, L and ZHU, YTT and al.}, year={2007}, pages={153–156} }
 @article{wang_huang_jiao_zhu_hamza_2006, title={Abnormal strain hardening in nanostructured titanium at high strain rates and large strains}, volume={42}, ISSN={0022-2461 1573-4803}, url={http://dx.doi.org/10.1007/S10853-006-0822-0}, DOI={10.1007/S10853-006-0822-0}, number={5}, journal={Journal of Materials Science}, publisher={Springer Science and Business Media LLC}, author={Wang, Y. M. and Huang, J. Y. and Jiao, T. and Zhu, Y. T. and Hamza, A. V.}, year={2006}, month={Dec}, pages={1751–1756} }
 @inbook{zhu_2006, place={Dordrecht}, series={NATO Science Series (II: Mathematics, Physics and Chemistry)}, title={Deformation Twinning in Nanocrystalline fcc Copper and Aluminum}, ISBN={1402039212}, url={http://dx.doi.org/10.1007/1-4020-3923-9_1}, DOI={10.1007/1-4020-3923-9_1}, booktitle={Nanostructured Materials by High-Pressure Severe Plastic Deformation}, publisher={Springer-Verlag}, author={Zhu, Yuntian T.}, editor={Zhu, Y.T. and Varyukhin, V.Editors}, year={2006}, month={Jan}, pages={3–11}, collection={NATO Science Series (II: Mathematics, Physics and Chemistry)} }
 @article{zhu_2006, title={Deformation twins formed in nanocrystalline materials}, volume={503-504}, journal={NANOMATERIALS BY SEVERE PLASTIC DEFORMATION}, author={ZHU, YT}, year={2006}, pages={125–132} }
 @article{li_depaula_zhang_al._2006, title={Drying induced upright sliding and reorganization of carbon nanotube arrays}, volume={17}, DOI={10.1088/0957-4484/17/18/001}, abstractNote={Driven by capillary force, wet carbon nanotube (CNT) arrays have been found to reorganize into cellular structures upon drying. During the reorganization process, individual CNTs are firmly attached to the substrate and have to lie down on the substrate at cell bottoms, forming closed cells. Here we demonstrate that by modifying catalyst structures, the adhesion of CNTs to the substrate can be weakened. Upon drying such CNT arrays, CNTs may slide away from their original sites on the surface and self-assemble into cellular patterns with bottoms open. It is also found that the sliding distance of CNTs increases with array height, and drying millimetre tall arrays leads to the sliding of CNTs over a few hundred micrometres and the eventual self-assembly into discrete islands. By introducing regular vacancies in CNT arrays, CNTs may be manipulated into different patterns.}, number={18}, journal={NANOTECHNOLOGY}, author={LI, QW and DEPAULA, R and ZHANG, XF and al.}, year={2006}, pages={4533–4536} }
 @article{pushin_valiev_zhu_al._2006, title={Effect of equal channel angular pressing and repeated rolling on structure, phase transformations and properties of TiNi shape memory alloys}, volume={503-504}, journal={NANOMATERIALS BY SEVERE PLASTIC DEFORMATION}, author={PUSHIN, VG and VALIEV, RZ and ZHU, YT and al.}, year={2006}, pages={539–544} }
 @article{pushin_valiev_zhu_al._2006, title={Effect of severe plastic deformation on the behavior of Ti-Ni shape memory alloys}, volume={47}, number={3}, journal={MATERIALS TRANSACTIONS}, author={PUSHIN, VG and VALIEV, RZ and ZHU, YT and al.}, year={2006}, pages={694–697} }
 @article{stolyarov_valiev_zhu_2006, title={Enhanced low-temperature impact toughness of nanostructured Ti}, volume={88}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2167800}, DOI={10.1063/1.2167800}, abstractNote={Impact toughness is one of the major mechanical properties for structural materials. It is generally observed that in coarse-grained materials the impact toughness decreases with decreasing testing temperature. Here, we report that the impact toughness of nanostructured Ti processed by severe plastic deformation is enhanced at low temperatures of −70°C and −196°C, a unique phenomenon that contradicts the observations in coarse-grained materials. The enhanced impact toughness is attributed to the increased strength and ductility of nanostructured Ti as well as smaller fracture dimples at lower temperatures. This result demonstrates the advantage of using nanostructured Ti in low-temperature applications.}, number={4}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Stolyarov, V. V. and Valiev, R. Z. and Zhu, Y. T.}, year={2006}, month={Jan}, pages={041905} }
 @article{liao_kilmametov_valiev_gao_li_mukherjee_bingert_zhu_2006, title={High-pressure torsion-induced grain growth in electrodeposited nanocrystalline Ni}, volume={88}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.2159088}, DOI={10.1063/1.2159088}, abstractNote={Deformation-induced grain growth has been reported in nanocrystalline (nc) materials under indentation and severe cyclic loading, but not under any other deformation mode. This raises an issue on critical conditions for grain growth in nc materials. This study investigates deformation-induced grain growth in electrodeposited nc Ni during high-pressure torsion (HPT). Our results indicate that high stress and severe plastic deformation are required for inducing grain growth, and the upper limit of grain size is determined by the deformation mode and parameters. Also, texture evolution suggests that grain-boundary-mediated mechanisms played a significant role in accommodating HPT strain.}, number={2}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Liao, X. Z. and Kilmametov, A. R. and Valiev, R. Z. and Gao, Hongsheng and Li, Xiaodong and Mukherjee, A. K. and Bingert, J. F. and Zhu, Y. T.}, year={2006}, month={Jan}, pages={021909} }
 @article{liao_kilmametov_valiev_al._2006, title={High-pressure torsion-induced grain growth in electrodeposited nanocrystalline Ni}, volume={88}, number={2}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and KILMAMETOV, AR and VALIEV, RZ and al.}, year={2006} }
 @inbook{saitova_semenova_raab_valiev_lowe_zhu_2006, place={Dordrecht}, series={NATO Science Series (II: Mathematics, Physics and Chemistry)}, title={Improving the Mechanical Properties of Ti-6Al-4V Alloy by Equal Channel Angular Pressing}, ISBN={1402039212, 9781402039218, 9781402039232}, url={http://dx.doi.org/10.1007/1-4020-3923-9_33}, DOI={10.1007/1-4020-3923-9_33}, booktitle={Nanostructured Materials by High-Pressure Severe Plastic Deformation}, publisher={Springer-Verlag}, author={Saitova, L.R. and Semenova, I.P. and Raab, G.I. and Valiev, R.Z. and Lowe, T.C. and Zhu, Y.T.}, editor={Zhu, Y.T. and Varyukhin, V.Editors}, year={2006}, month={Jan}, pages={241–246}, collection={NATO Science Series (II: Mathematics, Physics and Chemistry)} }
 @article{semenova_saitova_raab_al._2006, title={Microstructural features and mechanical properties of the Ti-6Al-4V ELI alloy processed by severe plastic deformation}, volume={503-504}, journal={NANOMATERIALS BY SEVERE PLASTIC DEFORMATION}, author={SEMENOVA, IP and SAITOVA, LR and RAAB, GI and al.}, year={2006}, pages={757–762} }
 @inbook{semenova_latysh_zhu_lowe_valiev_sadikova_2006, place={Dordrecht}, series={NATO Science Series (II: Mathematics, Physics and Chemistry}, title={Microstructure and Mechanical Properties of Long, Ultrafine-Grained Ti Rods}, ISBN={1402039212}, url={http://dx.doi.org/10.1007/1-4020-3923-9_32}, DOI={10.1007/1-4020-3923-9_32}, booktitle={Nanostructured Materials by High-Pressure Severe Plastic Deformation}, publisher={Springer-Verlag}, author={Semenova, I.P. and Latysh, V.V. and Zhu, Y.T. and Lowe, T.C. and Valiev, R.Z. and Sadikova, G.H.}, editor={Zhu, Y.T. and Varyukhin, V.Editors}, year={2006}, month={Jan}, pages={235–240}, collection={NATO Science Series (II: Mathematics, Physics and Chemistry} }
 @article{latysh_semenova_salimgareeva_al._2006, title={Microstructure and properties of Ti rods produced by multi-step SPD}, volume={503-504}, journal={NANOMATERIALS BY SEVERE PLASTIC DEFORMATION}, author={LATYSH, VV and SEMENOVA, IP and SALIMGAREEVA, GH and al.}, year={2006}, pages={763–768} }
 @article{zhu_2006, title={Nanostructured materials: From laboratory to commercialization}, volume={58}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-006-0211-9}, DOI={10.1007/S11837-006-0211-9}, number={4}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian T.}, year={2006}, month={Apr}, pages={27–27} }
 @article{han_huang_zhu_al._2006, title={Negative strain-rate sensitivity in a nanostructured aluminum alloy}, volume={8}, DOI={10.1002/adem.200600164}, abstractNote={The influence of strain rate in the range of 10–1 to 10–5 s–1 on the compression behavior of a cryomilled 5083 Al alloy is studied. The compression flow stress remains constant after an initial short strain hardening and a small stress dip, which indicates a dynamic saturation of dislocations. It is found that the compression flow stress increases with decreasing strain rate, which is believed to be attributed to dynamic strain aging.}, number={10}, journal={ADVANCED ENGINEERING MATERIALS}, author={HAN, BQ and HUANG, JY and ZHU, YT and al.}, year={2006}, pages={945–947} }
 @article{zheng_liao_zhu_2006, title={Parametnic study of carbon nanotube growth via cobalt-catalyzed ethanol decomposition}, volume={60}, DOI={10.1016/j.matlet.2005.12.060}, abstractNote={Ethanol has been found to be a superior carbon source that can produce clean carbon nanotubes with minimal amorphous carbon impurity. In this study we have investigated the influence of several synthesis parameters on the growth of carbon nanotubes via cobalt-catalyzed decomposition of ethanol on porous alumina substrates. The synthesis parameters investigated here include the synthesis temperature and time, the flow rate of carrier gas for ethanol, and the concentration of cobalt catalyst solution. Our results suggest that there exist a critical flow rate for ethanol carrier gas and a critical concentration of cobalt solution, below which no carbon nanotube can grow. There also exist optimum parametric windows for synthesis temperature and cobalt solution, within which clean carbon nanotubes grow readily.}, number={16}, journal={MATERIALS LETTERS}, author={ZHENG, LX and LIAO, XZ and ZHU, YT}, year={2006}, pages={1968–1972} }
 @article{wu_zhu_2006, title={Partial-dislocation-mediated processes in nanocrystalline Ni with nonequilibrium grain boundaries}, volume={89}, DOI={10.1063/1.2227639}, abstractNote={The partial-dislocation-mediated processes have so far eluded high-resolution transmission electron microscopy studies in nanocrystalline (nc) Ni with nonequilibrium grain boundaries. It is revealed that the nc Ni deformed largely by twinning instead of extended partials. The underlying mechanisms including dissociated dislocations, high residual stresses, and stress concentrations near stacking faults are demonstrated and discussed.}, number={3}, journal={APPLIED PHYSICS LETTERS}, author={WU, XL and ZHU, YT}, year={2006} }
 @article{wu_zhu_ma_2006, title={Predictions for partial-dislocation-mediated processes in nanocrystalline Ni by generalized planar fault energy curves: An experimental evaluation}, volume={88}, DOI={10.1063/1.2186968}, abstractNote={Generalized planar fault energy (GPFE) curves have been used to predict partial-dislocation-mediated processes in nanocrystalline materials, but their validity has not been evaluated experimentally. We report experimental observations of a large quantity of both stacking faults and twins in nc Ni deformed at relatively low stresses in a tensile test. The experimental findings indicate that the GPFE curves can reasonably explain the formation of stacking faults, but they alone were not able to adequately predict the propensity of deformation twinning.}, number={12}, journal={APPLIED PHYSICS LETTERS}, author={WU, XL and ZHU, YT and MA, E}, year={2006} }
 @article{valiev_estrin_horita_langdon_zechetbauer_zhu_2006, title={Producing bulk ultrafine-grained materials by severe plastic deformation}, volume={58}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-006-0213-7}, DOI={10.1007/S11837-006-0213-7}, abstractNote={This overview highlights very recent achievements and new trends in one of the most active and developing fields in modern materials science: the production of bulk ultrafine-grained (UFG) materials using severe plastic deformation (SPD). The article also summarizes the chronology of early work in SPD processing and presents clear and definitive descriptions of the terminology currently in use in this research area. Special attention is given to the principles of the various SPD processing techniques as well as the major structural features and unique properties of bulk UFG materials that underlie their prospects for widespread practical utilization.}, number={4}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Valiev, Ruslan Z. and Estrin, Yuri and Horita, Zenji and Langdon, Terence G. and Zechetbauer, Michael J. and Zhu, Yuntian T.}, year={2006}, month={Apr}, pages={33–39} }
 @article{valiev_estrin_horita_al._2006, title={Producing bulk ultrafine-grained materials by severe plastic deformation}, volume={58}, number={4}, journal={JOM}, author={VALIEV, RZ and ESTRIN, Y and HORITA, Z and al.}, year={2006}, pages={33–39} }
 @article{li_zhu_kinloch_al._2006, title={Self-organization of carbon nanotubes in evaporating droplets}, volume={110}, DOI={10.1021/jp061554c}, abstractNote={Here, we report a simple and efficient way for organizing carbon nanotubes, in particular, single-wall carbon nanotubes (SWNTs) into ordered structures from their dilute solutions. It was found that drying a droplet of carbon nanotube solution at room temperature on a wettable surface such as glass or silica wafer led to redistribution, accumulation, and organization of carbon nanotubes along the perimeter of the droplet. Unlike the aggregation behaviors of colloid nanoparticles, anistropic carbon nanotubes tended to show two orientations in a ring deposit: one parallel to the outer perimeter of the ring and the other normal to it in the interior. Drying droplets of SWNT solutions at high temperatures exhibited a long-range ordered structure. In addition, droplet drying may cause size separation of carbon nanotubes and pattern formation through interactions between droplets. This result helps us not only to further understand fluid dynamics during the drying process but also to provide a promising and simple strategy for either assembling carbon nanotubes on a surface or organizing them into well-aligned films and fibers.}, number={28}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={LI, QW and ZHU, YT and KINLOCH, IA and al.}, year={2006}, pages={13926–13930} }
 @article{pushin_valiev_zhu_al._2006, title={Severe plastic deformation of melt-spun shape memory Ti2NiCu and Ni2MnGa alloys}, volume={47}, number={3}, journal={MATERIALS TRANSACTIONS}, author={PUSHIN, VG and VALIEV, RZ and ZHU, YT and al.}, year={2006}, pages={546–549} }
 @article{zhao_liao_cheng_al._2006, title={Simultaneously increasing the ductility and strength of nanostructured alloys}, volume={18}, DOI={10.1002/adma.200600310}, abstractNote={In this paper we report a strategy to simultaneously increase the ductility and strength of bulk nanostructured materials. By engineering very small second-phase particles into a nanostructured Al alloy matrix, we were able to more than double its uniform elongation, while further gaining rather than sacrificing its yield strength. The simultaneous enhancement of ductility and strength is due to the increased dislocation accumulation and resistance to dislocation-slip by second-phase particles, respectively. Our strategy is applicable to many nanostructured alloys and composites, and paves a way for their large-scale industrial applications. The material used in this model study is 7075 Al alloy. The alloy was solution-treated to obtain a coarse-grained (CG) solid solution. The CG sample was immediately cryogenically rolled to produce nanostructures with an average grain size of ca. 100 nm (designated as NS sample). The NS sample was then aged at low temperature to introduce very small secondphase particles (designated as NS+P sample). The engineering stress–strain curves of these samples are compared in Figure 1a. The 0.2 % yield strengths (marked by circles) of the CG, NS, and NS+P samples are 145 MPa, 550 MPa, and 615 MPa, respectively. Therefore, the low-temperature aging enhanced the yield strength of the NS sample by 12 %. The uniform elongation (marked by the symbol on the curves in Fig. 1a) was determined by the Considere criterion (Eq. 1) governing the onset of localized deformation [8]}, number={17}, journal={ADVANCED MATERIALS}, author={ZHAO, YH and LIAO, XZ and CHENG, S and al.}, year={2006}, pages={2280-+} }
 @article{zhao_bingert_liao_al._2006, title={Simultaneously increasing the ductility and strength of ultra-fine-grained pure copper}, volume={18}, DOI={10.1002/adma.200601472}, abstractNote={Bulk ultra-fine-grained (UFG) materials produced by severe plastic deformation (SPD) usually have high strength but relatively low ductility at ambient temperatures. This low ductility is attributed to insufficient strain hardening due to an inability to accumulate dislocations. For a singlephased UFG material where dislocation slip is the primary deformation mechanism, a long-standing fundamental question concerns the feasibility of developing microstructures that offer high ductility without sacrificing strength. The answer appears to be positive because there are some isolated examples where excellent mechanical behavior has been observed. Nevertheless, the structural features contributing to high strength and good ductility remain undefined, and this lack of understanding has hindered the search for effective procedures to simultaneously improve the strength and ductility of UFG materials. Here, we report a new process in which high ductility is achieved without sacrificing strength by plastically deforming UFG Cu in liquid nitrogen. The enhanced ductility is attributed primarily to the presence of a high density of preexisting deformation twins (PDTs) and also possibly to a large fraction of high-angle grain boundaries (HAGBs) formed during cryogenic processing. We conclude that this procedure provides a new strategy for increasing the ductility of UFG materials without any concurrent loss in strength. Strength and ductility are often mutually exclusive, i.e., materials may be strong or ductile but are rarely both. This also applies to bulk UFG materials. The low ductility of UFG materials has invariably limited their practical application and, accordingly, much attention has been paid to the development of strategies for improving this poor ductility. For singlephase UFG and nanostructured materials, several of the reports documenting high ductility and strength describe experiments on Cu where the stacking-fault energy is relatively low. In some investigations the high ductility was attributed to the development of a bimodal grain size distribution or pre-existing growth twins (PGTs), but in other investigations the reasons for the high ductility were not clearly defined. In practice, however, a bimodal grain size distribution must sacrifice some of the strength gained from nanostructuring. Another challenge is the need to fabricate UFG materials in large bulk form suitable for structural applications. This requirement has been hindered because the evidence suggests that PGTs occur only in electrodeposited thin films of nanostructured Cu, and in nanocrystalline Cu by inert-gas condensation (IGC) followed by compaction. However, the ductility of IGC-prepared nanocrystalline Cu is very low. The objectives of this study were twofold: First, to develop a procedure for increasing the ductility of large bulk UFG Cu without incurring any significant loss in strength. Second, to evaluate the mechanism contributing to high ductility in UFG Cu. A pure Cu (99.99%) bar was initially processed by equalchannel angular pressing (ECAP) to produce a UFG structure (hereafter designated the UFGECAP sample), then cryodrawn (D) to a reduction in area of ca. 95%, followed by cryorolling (R) with a reduction in thickness of ca. 96% (hereafter designated the UFGECAP+D+R sample). Figure 1a shows that the UFGECAP+D+R sample has superior mechanical properties compared to the UFGECAP sample. The UFGECAP Cu sample has a 0.2% yield strength of ca. 410 MPa ( ), which is significantly higher than the value of ca. 40 MPa in coarse-grained (CG) Cu. In addition, necking occurs rapidly after the stress reaches a maximum value, yielding a uniform elongation of only ca. 1.3% and an elongation to failure of only ca. 5.9% in the UFGECAP sample. By contrast, the yield strength is increased to ca. 500 MPa in the UFGECAP+D+R sample, and, more importantly, this sample undergoes strain hardening, giving a uniform elongation of C O M M U N IC A IO N S}, number={22}, journal={ADVANCED MATERIALS}, author={ZHAO, YH and BINGERT, JE and LIAO, XZ and al.}, year={2006}, pages={2949-+} }
 @article{han_huang_zhu_al._2006, title={Strain rate dependence of properties of cryomilled bimodal 5083 Al alloys}, volume={54}, DOI={10.1016/j.actamat.2006.02.045}, abstractNote={The strain-rate-dependent deformation behavior of bimodal 5083 Al alloys processed by cryomilling is studied in the present investigation. The alloys were processed by hot extrusion of a mixture of cryomilled and unmilled Al powders. Their tensile stress–strain curves displayed a short work-hardening region, followed by a small stress drop after the ultimate stress while their tensile ductility increased with decreasing strain rates. Compressive stress–strain curves displayed a nearly perfect plastic behavior and negative strain rate sensitivity. Inspection of the deformation characteristics and fractography revealed that the higher ductility at lower strain rate was caused by effective diffusion-mediated stress relaxation, which delayed microcrack nucleation and propagation. Furthermore, crack blunting/bridging by ductile coarse grains played a significant role at lower strain rates. The phenomenon of the negative strain rate sensitivity of compression flow stress is proposed to be as a consequence of dynamic strain aging.}, number={11}, journal={ACTA MATERIALIA}, author={HAN, BQ and HUANG, JY and ZHU, YT and al.}, year={2006}, pages={3015–3024} }
 @inbook{stolyarov_prokofiev_valiev_lowe_zhu_2006, place={Dordrecht}, series={NATO Science Series (II: Mathematics, Physics and Chemistry)}, title={Structure and Properties of Ti Alloys Processed by ECAP}, ISBN={1402039212, 9781402039218}, url={http://dx.doi.org/10.1007/1-4020-3923-9_23, 9781402039232}, DOI={10.1007/1-4020-3923-9_23}, booktitle={Nanostructured Materials by High-Pressure Severe Plastic Deformation}, publisher={Springer-Verlag}, author={Stolyarov, V. V. and Prokofiev, E. A. and Valiev, R. Z. and Lowe, T. C. and Zhu, Y. T.}, editor={Zhu, Y.T. and Varyukhin, V.Editors}, year={2006}, month={Jan}, pages={169–174}, collection={NATO Science Series (II: Mathematics, Physics and Chemistry)} }
 @article{li_zhang_depaula_al._2006, title={Sustained growth of ultralong carbon nanotube arrays for fiber spinning}, volume={18}, DOI={10.1002/adma.200601344}, abstractNote={Carbon nanotubes (CNTs) are the strongest materials ever discovered by mankind. With measured tensile strengths as high as 150 GPa and a high modulus of 1 TPa, CNTs are very promising for many high-strength, lightweight applications. Several approaches have been reported to process micrometer-long CNTs into fibers, including dispersing CNTs into polymer or acid solutions and then spinning them into composite or pure CNT fibers. Unfortunately, difficulties in CNT dispersion and alignment have hindered the full utilization of CNT strength. Recently, CNT yarns have been directly spun from CNT arrays. This new approach has the advantage of good CNT alignment and high CNT volume fraction, and therefore is very promising for producing higher strength CNTyarns and fibers. So far, CNT fibers can only be spun from CNTarrays that are less than 300 lm long, and this has limited their tensile strengths to only a few hundred MPa. Therefore, it is critical to synthesize spinnable long CNT arrays so that higher strength can be obtained in the spun CNT fibers. Long active growth is the key to growing long CNT arrays. However, during CVD processes using thin Fe catalyst films, the catalysts usually become inactive within several minutes due to either interdiffusion with the substrate or the accumulation of amorphous carbon. In order to achieve sustained growth for long CNT arrays, catalysts like ferrocene have been added continuously or intermittently into the system to nucleate new catalyst particles during the growth. This makes individual CNTs much shorter than the array height. In addition, CNTs synthesized in this way are often thick and dirty with undesirable excessive catalytic particles and amorphous carbon. Alternatively, sustained growth was realized by introducing a thin buffer layer, either Al2O3 [18,19]}, number={23}, journal={ADVANCED MATERIALS}, author={LI, QW and ZHANG, XF and DEPAULA, RF and al.}, year={2006}, pages={3160-+} }
 @article{zhao_zhu_liao_al._2006, title={Tailoring stacking fault energy for high ductility and high strength in ultrafine grained Cu and its alloy}, volume={89}, DOI={10.1063/1.2356310}, abstractNote={Bulk ultrafine grained (UFG) materials produced by severe plastic deformation often have low ductility. Here the authors report that simultaneous increases in ductility and strength can be achieved by tailoring the stacking fault energy (SFE) via alloying. Specifically, UFG bronze (Cu 10wt.% Zn) with a SFE of 35mJ∕m2 was found to have much higher strength and ductility than UFG copper with a SFE of 78mJ∕m2. Accumulations of both twins and dislocations during tensile testing play a significant role in enhancing the ductility of the UFG bronze. This work demonstrates a strategy for designing UFG alloys with superior mechanical properties.}, number={12}, journal={APPLIED PHYSICS LETTERS}, author={ZHAO, YH and ZHU, YT and LIAO, XZ and al.}, year={2006} }
 @article{wu_zhu_chen_ma_2006, title={Twinning and stacking fault formation during tensile deformation of nanocrystalline Ni}, volume={54}, ISSN={1359-6462}, url={http://dx.doi.org/10.1016/j.scriptamat.2005.12.045}, DOI={10.1016/j.scriptamat.2005.12.045}, abstractNote={Deformation twins and stacking faults have been observed in nanocrystalline Ni, for the first time under uniaxial tensile test conditions. These partial dislocation mediated deformation mechanisms are enhanced at cryogenic test temperatures. Our observations highlight the effects of deformation conditions, temperature in particular, on deformation mechanisms in nanograins.}, number={9}, journal={Scripta Materialia}, publisher={Elsevier BV}, author={Wu, X. and Zhu, Y.T. and Chen, M.W. and Ma, E.}, year={2006}, month={May}, pages={1685–1690} }
 @article{wu_zhu_chen_al._2006, title={Twinning and stacking fault formation during tensile deformation of nanocrystalline Ni}, volume={54}, number={9}, journal={SCRIPTA MATERIALIA}, author={WU, X and ZHU, YT and CHEN, MW and al.}, year={2006}, pages={1685–1690} }
 @article{ungár_balogh_zhu_horita_xu_langdon_2007, title={Using X-ray microdiffraction to determine grain sizes at selected positions in disks processed by high-pressure torsion}, volume={444}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2006.08.059}, DOI={10.1016/j.msea.2006.08.059}, abstractNote={Disks of pure Cu, Cu–10% Zn and Cu–30% Zn were processed by high-pressure torsion (HPT) and then examined at selected positions using microhardness testing and X-ray microdiffraction line broadening. The results show excellent agreement between the microhardness measurements and X-ray microdiffraction. The grain sizes and the microhardness values are essentially constant across the diameters of the disks of pure Cu and the Cu–30% Zn alloy but for the Cu–10% Zn alloy the measured grain size is largest and the hardness is lowest in the center of the disk. The results demonstrate the potential for achieving a reasonably homogeneous microstructure in samples processed by HPT.}, number={1-2}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Ungár, Tamás and Balogh, Levente and Zhu, Yuntian T. and Horita, Zenji and Xu, Cheng and Langdon, Terence G.}, year={2007}, month={Jan}, pages={153–156} }
 @misc{zhu_2005, title={Book Review: Plastic Deformation in Nanocrystalline Materials. By M. Yu. Gutkin and I. A. Ovid'ko.}, volume={17}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/adma.200590101}, DOI={10.1002/adma.200590101}, abstractNote={Advanced MaterialsVolume 17, Issue 20 p. 2513-2514 Book Review Book Review: Plastic Deformation in Nanocrystalline Materials. By M. Yu. Gutkin and I. A. Ovid'ko. Yuntian T. Zhu, Search for more papers by this author Yuntian T. Zhu, Search for more papers by this author First published: 07 October 2005 https://doi.org/10.1002/adma.200590101Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onEmailFacebookTwitterLinked InRedditWechat No abstract is available for this article.Citing Literature Volume17, Issue20October, 2005Pages 2513-2514 RelatedInformation}, number={20}, journal={Advanced Materials}, publisher={Wiley}, author={Zhu, Yuntian T.}, year={2005}, month={Oct}, pages={2513–2514} }
 @article{srinivasan_liao_baskes_al._2005, title={Compact and dissociated dislocations in aluminum: Implications for deformation}, volume={94}, number={12}, journal={PHYSICAL REVIEW LETTERS}, author={SRINIVASAN, SG and LIAO, XZ and BASKES, MI and al.}, year={2005} }
 @article{valiev_zhu_2005, title={Contribution of early works by Terence G. Langdon to modern materials science}, volume={410-411}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2005.08.105}, DOI={10.1016/j.msea.2005.08.105}, abstractNote={Professor Terence G. Langdon has been ranked as the second most cited author in materials science of the last 10 years by the international Institute for Scientific Information (Philadelphia, PA, USA). An analysis of his works shows that his most highly cited publications are those dealing with recent studies of microstructural evolution and mechanical properties of ultrafine-grained (UFG) materials processed by severe plastic deformation, as well as earlier papers on creep and superplasticity carried out in the 1970–1980s. This paper overviews the landmarks in the research activity of Prof. Langdon, and traces how his early works have affected the current investigations of the mechanical behavior of UFG materials produced by severe plastic deformation.}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Valiev, Ruslan Z. and Zhu, Yuntian T.}, year={2005}, month={Nov}, pages={5–7} }
 @article{zhu_2005, title={Deformation twinning in nanocrystalline metals}, volume={14}, number={4}, journal={JOURNAL OF MATERIALS ENGINEERING AND PERFORMANCE}, author={ZHU, YT}, year={2005}, pages={467–472} }
 @article{liao_macmanus-driscoll_zhu_peterson_xu_2005, title={Disordered Phases in Magnetoresistance Sr2FeMoO6 Induced by Cation Deficiency}, volume={11}, ISSN={1431-9276 1435-8115}, url={http://dx.doi.org/10.1017/S1431927605503593}, DOI={10.1017/S1431927605503593}, abstractNote={Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005}, number={S02}, journal={Microscopy and Microanalysis}, publisher={Cambridge University Press (CUP)}, author={Liao, X Z and MacManus-Driscoll, J L and Zhu, Y T and Peterson, D E and Xu, H F}, year={2005}, month={Aug} }
 @article{la_ma_zhu_yang_liu_xue_valiev_2005, title={Dry-sliding tribological properties of ultrafine-grained Ti prepared by severe plastic deformation}, volume={53}, ISSN={1359-6454}, url={http://dx.doi.org/10.1016/j.actamat.2005.07.031}, DOI={10.1016/j.actamat.2005.07.031}, abstractNote={This paper reports the tribological properties of ultrafine-grained (UFG) Ti prepared by severe plastic deformation under dry sliding against AISI52100 steel in ambient environment and at varying load and sliding speed. Worn surfaces of the UFG Ti were examined with a scanning electron microscope and X-ray photoelectron spectroscope. It was found that the wear rate of the UFG Ti under dry sliding was of the magnitude of 10−3 mm3 m−1, which is lower than that of the annealed coarse-grained (CG) Ti. The wear rate of the UFG Ti increased with the load, while it decreased with the sliding speed. The friction coefficient of the UFG Ti was in the range of 0.45–0.60, slightly lower than that of the CG Ti, and did not change with the load and sliding time after the initial transient period. The friction coefficient increased with increasing sliding speed to a maximum point and then decreased. The wear mechanism of the UFG Ti was micro-ploughing and delamination. The worn surfaces were covered by a TiO2 layer. These results demonstrated that UFG structures improved the wear resistance but did not significantly affect the friction coefficient of Ti.}, number={19}, journal={Acta Materialia}, publisher={Elsevier BV}, author={La, PeiQing and Ma, JiQiang and Zhu, Yuntian T. and Yang, Jun and Liu, WeiMin and Xue, QunJi and Valiev, Ruslan Z.}, year={2005}, month={Nov}, pages={5167–5173} }
 @article{la_ma_zhu_al._2005, title={Dry-sliding tribological properties of ultrafine-grained Ti prepared by severe plastic deformation}, volume={53}, number={19}, journal={ACTA MATERIALIA}, author={LA, PQ and MA, JQ and ZHU, YT and al.}, year={2005}, pages={5167–5173} }
 @article{han_huang_zhu_al._2006, title={Effect of strain rate on the ductility of a nanostructured aluminum alloy}, volume={54}, DOI={10.1016/j.scriptamat.2005.11.035}, abstractNote={Nanostructured materials normally exhibit enhanced ductility at higher strain rate. In this paper we report the observation that a cryomilled nanostructured 5083 Al alloy exhibits the opposite behavior, i.e., higher ductility at lower strain rates. This phenomenon was rationalized by a diffusion-mediated stress relaxation mechanism that effectively delayed crack initiation events.}, number={6}, journal={SCRIPTA MATERIALIA}, author={HAN, BQ and HUANG, JY and ZHU, YT and al.}, year={2006}, pages={1175–1180} }
 @article{wang_liao_xu_al._2005, title={Effects of Eu interfacial mobility on the growth of epitaxial EuBa2Cu3O7-delta films}, volume={86}, DOI={10.1063/1.1881779}, abstractNote={By inserting a thin YBa2Cu3O7−δ (Y123) seed layer, high quality EuBa2Cu3O7−δ (Eu123) films can grow with epitaxial c-axis orientation on SrTiO3 (STO) substrate without increasing the growth temperature. The interfacial structures of Eu123∕STO and Eu123∕Y123∕STO were investigated using scanning transmission electron microscopy. Results show that the Eu mobility on the STO substrate is very low at the regular deposition temperature. This leads to nonuniform composition distribution at the Eu123∕STO interface and a mixture of c-axis and a-axis growth. A thin Y123 seed layer greatly improves the Eu mobility and therefore facilitates high quality c-axis growth.}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={WANG, H and LIAO, XZ and XU, HF and al.}, year={2005} }
 @article{zhao_liao_zhu_al._2005, title={Enhanced mechanical properties in ultrafine grained 7075 Al alloy}, volume={20}, number={2}, journal={JOURNAL OF MATERIALS RESEARCH}, author={ZHAO, YH and LIAO, XZ and ZHU, YT and al.}, year={2005}, pages={288–291} }
 @article{zhu_liao_valiev_2005, title={Formation mechanism of fivefold deformation twins in nanocrystalline face-centered-cubic metals}, volume={86}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1879111}, DOI={10.1063/1.1879111}, abstractNote={Fivefold deformation twins have been recently observed in nanocrystalline face-centered-cubic (fcc) metals and alloys synthesized by severe plastic deformation techniques. However, numerous molecular dynamics simulations in the literature have not observed fivefold deformation twins in nanocrystalline fcc metals. The discrepancy between experimental observations and molecular dynamics simulations has raised an issue on their formation mechanism and conditions. Here we propose a sequential twinning mechanism that provides a clear path for the formation of fivefold deformation twins. The mechanism requires an orientation change of applied stresses, which explains why molecular dynamics simulations under a constant load orientation do not produce fivefold deformation twins.}, number={10}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Zhu, Y. T. and Liao, X. Z. and Valiev, R. Z.}, year={2005}, month={Mar}, pages={103112} }
 @article{zhu_liao_2005, title={Formation mechanism of fivefold deformation twins in nanocrystalline face-centered-cubic metals}, volume={86}, number={10}, journal={APPLIED PHYSICS LETTERS}, author={ZHU, YT and LIAO, XZ}, year={2005} }
 @article{xue_liao_zhu_gray_2005, title={Formation mechanisms of nanostructures in stainless steel during high-strain-rate severe plastic deformation}, volume={410-411}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2005.08.022}, DOI={10.1016/j.msea.2005.08.022}, abstractNote={We have investigated the formation mechanisms of nanostructures within adiabatic shear bands formed in stainless steel samples deformed by high-strain-rate forced shear. Twinning is shown to play a critical role in the initiation of nanostructures. Secondary twins directly led to the formation of elongated subgrains. Microtwins inside shear bands promoted division and break-down of the subgrains, which further refined the microstructures.}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Xue, Q. and Liao, X.Z. and Zhu, Y.T. and Gray, G.T., III}, year={2005}, month={Nov}, pages={252–256} }
 @article{xue_liao_zhu_al._2005, title={Formation mechanisms of nanostructures in stainless steel during high-strain-rate severe plastic deformation}, volume={410}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={XUE, Q and LIAO, XZ and ZHU, YT and al.}, year={2005}, pages={252–256} }
 @article{zhu_langdon_2005, title={Influence of grain size on deformation mechanisms: An extension to nanocrystalline materials}, volume={409}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2005.05.111}, DOI={10.1016/j.msea.2005.05.111}, abstractNote={The deformation mechanisms occurring in coarse-grained polycrystalline materials are now understood reasonably well. The primary deformation processes are associated with the intragranular movement of dislocations either through crystallographic slip at low temperatures or through a combination of dislocation climb and glide at high temperatures. Intergranular processes become important in polycrystalline materials with small grain sizes including stress-directed vacancy diffusion and grain boundary sliding. It has been shown using molecular dynamic simulations, and confirmed in experiments, that different processes may become important when the grain size is reduced to the nanometer level. Partial dislocation emission from grain boundaries becomes a dominant process at grain sizes of 10–50 nm and this leads to the formation of deformation twins even in materials with high stacking-fault energies such as aluminum. Grain boundary sliding also becomes dominant at grain sizes below ∼10 nm at low temperatures. This paper examines the influence of grain size on the deformation mechanisms in polycrystalline materials with special emphasis on the new mechanisms that become important at the nanocrystalline level.}, number={1-2}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Zhu, Yuntian T. and Langdon, Terence G.}, year={2005}, month={Nov}, pages={234–242} }
 @article{zhao_liao_zhu_al._2005, title={Influence of stacking fault energy on nanostructure formation under high pressure torsion}, volume={410}, DOI={10.1016/j.msea.2005.08.074}, abstractNote={Copper, bronze (Cu–10 wt.% Zn) and brass (Cu–30 wt.% Zn) were deformed by high pressure torsion (HPT) under a pressure of 6 GPa for five rotations. The stacking fault energies (SFEs) of copper, bronze and brass are 78, 35 and 14 mJ/m2, respectively, and their average grain sizes after the HPT processing were about 84, 54 and 17 nm, respectively. Deformation twins were found in all samples and their densities increased with decreasing SFE. This work demonstrates that under the same conditions of HPT a low SFE promotes the formation of nanostructures and deformation twins.}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHAO, YH and LIAO, XZ and ZHU, YT and al.}, year={2005}, pages={188–193} }
 @article{pushin_stolyarov_valiev_lowe_zhu_2005, title={Nanostructured TiNi-based shape memory alloys processed by severe plastic deformation}, volume={410-411}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2005.08.071}, DOI={10.1016/j.msea.2005.08.071}, abstractNote={We present the processing, microstructure and properties of nanostructured TiNi-based shape-memory alloys synthesized by severe plastic deformation (SPD), including high-pressure torsion, equal-channel angular pressing, and multi-step SPD deformation (SPD plus cold rolling or drawing). It was found that the SPD processing did not alter the phase transformation sequence of the alloys but changed the morphology of the martensite. Also, we found that the mechanical and shape memory properties were improved by forming nanostructures in these alloys; SPD processing rendered a higher recovery stress (up to 1.5 GPa) and a higher maximum reverse strain (up to 10%) of shape memory, which are desirable in various practical applications.}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Pushin, V.G. and Stolyarov, V.V. and Valiev, R.Z. and Lowe, T.C. and Zhu, Y.T.}, year={2005}, month={Nov}, pages={386–389} }
 @article{pushin_stolyarov_valiev_al._2005, title={Nanostructured TiNi-based shape memory alloys processed by severe plastic deformation}, volume={410}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={PUSHIN, VG and STOLYAROV, VV and VALIEV, RZ and al.}, year={2005}, pages={386–389} }
 @article{zhu_liao_srinivasan_lavernia_2005, title={Nucleation of deformation twins in nanocrystalline face-centered-cubic metals processed by severe plastic deformation}, volume={98}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.2006974}, DOI={10.1063/1.2006974}, abstractNote={Nanocrystalline (nc) materials are known to deform via mechanisms not accessible to their coarse-grained counterparts. For example, deformation twins and partial dislocations emitted from grain boundaries have been observed in nc Al and Cu synthesized by severe plastic deformation (SPD). This paper further develops an earlier dislocation-based model on the nucleation of deformation twins in nc face-centered-cubic (fcc) metals. It is found that there exists an optimum grain-size range in which deformation twins nucleate most readily. The critical twinning stress is found determined primarily by the stacking fault energy while the optimum grain size is largely determined by ratio of shear modulus to stacking fault energy. This model formulated herein is applicable to fcc nanomaterials synthesized by SPD techniques and provide a lower bound to the critical twining stress.}, number={3}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Zhu, Y. T. and Liao, X. Z. and Srinivasan, S. G. and Lavernia, E. J.}, year={2005}, month={Aug}, pages={034319} }
 @article{zhu_liao_srinivasan_al._2005, title={Nucleation of deformation twins in nanocrystalline face-centered-cubic metals processed by severe plastic deformation}, volume={98}, number={3}, journal={JOURNAL OF APPLIED PHYSICS}, author={ZHU, YT and LIAO, XZ and SRINIVASAN, SG and al.}, year={2005} }
 @article{doorn_o’connell_zheng_al._2005, title={Raman spectral imaging of a carbon nanotube intramolecular junction}, volume={94}, number={1}, journal={PHYSICAL REVIEW LETTERS}, author={DOORN, SK and O’CONNELL, MJ and ZHENG, LX and al.}, year={2005} }
 @article{doorn_zheng_o’connell_al._2005, title={Raman spectroscopy and imaging of ultralong carbon nanotubes}, volume={109}, DOI={10.1021/jp0463159}, abstractNote={Raman spectroscopy and confocal Raman imaging with 514 nm excitation was performed on recently developed ultralong carbon nanotubes grown by the "fast-heating" chemical vapor deposition (CVD) method. The ultralong nanotubes are found to consist of both semiconducting and metallic types, with spectra that are consistent with the nanotubes being single walled. Characterization of nanotube diameters shows that short nanotubes appearing near the sample catalyst region have a broader distribution than is observed for the ultralong nanotubes. The narrow diameter distribution is determined by uniformity of catalyst particle size and gives additional evidence for the proposed "kite" mechanism for long nanotube growth. Raman imaging was performed over large length scales (up to 140 microm). Imaging reveals the ultralong nanotubes to be of high quality, with a very low defect density. Variations in G-band frequencies and intensity demonstrate the occurrence of minor structural changes and variations in nanotube-substrate interaction along the length of the nanotubes. Evidence also demonstrates that larger structural changes resulting in a full chirality change can occur in these nanotube types to produce a metal-to-semiconductor intramolecular junction.}, number={9}, journal={JOURNAL OF PHYSICAL CHEMISTRY B}, author={DOORN, SK and ZHENG, LX and O’CONNELL, MJ and al.}, year={2005}, pages={3751–3758} }
 @article{zhu_horita_xia_berbon_raj_chokshi_kostorz_2005, title={The Langdon Symposium: Flow and Forming of Crystalline Materials}, volume={410-411}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2005.08.106}, DOI={10.1016/j.msea.2005.08.106}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Zhu, Yuntian T. and Horita, Zenji and Xia, Kenong and Berbon, Patrick B. and Raj, Sai V. and Chokshi, Atul H. and Kostorz, Gernot}, year={2005}, month={Nov}, pages={1–2} }
 @article{wang_zhao_tait_al._2004, title={A quenchable superhard carbon phase synthesized by cold compression of carbon nanotubes}, volume={101}, number={38}, journal={PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA}, author={WANG, ZW and ZHAO, YS and TAIT, K and al.}, year={2004}, pages={13699–13702} }
 @article{huang_zhu_liao_valiev_2004, title={Amorphization of TiNi induced by high-pressure torsion}, volume={84}, ISSN={0950-0839 1362-3036}, url={http://dx.doi.org/10.1080/09500830310001657353}, DOI={10.1080/09500830310001657353}, abstractNote={Using high-resolution electron microscopy, we investigated the initial stages of high-pressure-torsion-induced crystalline-to-amorphous transformation of TiNi. It is found that the deformation-induced amorphization initiated from dislocation core regions in the interior of grains and from grain boundaries. It is believed that both the energy stored in the dislocations and the energy stored in the grain boundaries contribute significantly to driving the crystalline-to-amorphous transformation.}, number={3}, journal={Philosophical Magazine Letters}, publisher={Informa UK Limited}, author={Huang, J. Y. and Zhu, Y. T. and Liao, X. Z. and Valiev, R. Z.}, year={2004}, month={Mar}, pages={183–190} }
 @article{huang_zhu_liao_al._2004, title={Amorphization of TiNi induced by high-pressure torsion}, volume={84}, number={3}, journal={PHILOSOPHICAL MAGAZINE LETTERS}, author={HUANG, JY and ZHU, YT and LIAO, XZ and al.}, year={2004}, pages={183–190} }
 @article{raab_valiev_lowe_al._2004, title={Continuous processing of ultrafine grained Al by ECAP-Conform}, volume={382}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={RAAB, GJ and VALIEV, RZ and LOWE, TC and al.}, year={2004}, pages={30–34} }
 @article{raab_valiev_lowe_zhu_2004, title={Continuous processing of ultrafine grained Al by ECAP–Conform}, volume={382}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2004.04.021}, DOI={10.1016/j.msea.2004.04.021}, abstractNote={In this paper, we report a new severe plastic deformation (SPD) technique, which combines equal channel angular pressing (ECAP) with Conform, to process ultrafine grained (UFG) materials in a continuous manner. ECAP in its original form can only process short metal bars and is labor intensive. Conform is a technique that has been used to continuously form metals into various shapes. By combining these two techniques, we were able to produce UFG structures in an Al wire and to significantly increase its strength.}, number={1-2}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Raab, Georgy J. and Valiev, Ruslan Z. and Lowe, Terry C. and Zhu, Yuntian T.}, year={2004}, month={Sep}, pages={30–34} }
 @article{balyanov_kutnyakova_amirkhanova_al._2004, title={Corrosion resistance of ultra fine-grained Ti}, volume={51}, number={3}, journal={SCRIPTA MATERIALIA}, author={BALYANOV, A and KUTNYAKOVA, J and AMIRKHANOVA, NA and al.}, year={2004}, pages={225–229} }
 @article{liao_zhao_srinivasan_zhu_valiev_gunderov_2004, title={Deformation twinning in nanocrystalline copper at room temperature and low strain rate}, volume={84}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1644051}, DOI={10.1063/1.1644051}, abstractNote={The grain-size effect on deformation twinning in nanocrystalline copper is studied. It has been reported that deformation twinning in coarse-grained copper occurs only under high strain rate and/or low-temperature conditions. Furthermore, reducing grain sizes has been shown to suppress deformation twinning. Here, we show that twinning becomes a major deformation mechanism in nanocrystalline copper during high-pressure torsion under a very slow strain rate and at room temperature. High-resolution transmission electron microscopy investigation of the twinning morphology suggests that many twins and stacking faults in nanocrystalline copper were formed through partial dislocation emissions from grain boundaries. This mechanism differs from the pole mechanism operating in coarse-grained copper.}, number={4}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Liao, X. Z. and Zhao, Y. H. and Srinivasan, S. G. and Zhu, Y. T. and Valiev, R. Z. and Gunderov, D. V.}, year={2004}, month={Jan}, pages={592–594} }
 @article{liao_zhao_srinivasan_al._2004, title={Deformation twinning in nanocrystalline copper at room temperature and low strain rate}, volume={84}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and ZHAO, YH and SRINIVASAN, SG and al.}, year={2004}, pages={592–594} }
 @article{huang_zhu_alexander_liao_lowe_asaro_2004, title={Development of repetitive corrugation and straightening}, volume={371}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/S0921-5093(03)00114-X}, DOI={10.1016/S0921-5093(03)00114-X}, abstractNote={In this paper, we present recent developments in repetitive corrugation and straightening (RCS), a new severe plastic deformation (SPD) technique. Two refinements of the original RCS method are presented and results are shown for commercial purity copper that illustrate the associated improvements in the effectiveness of nanostructuring. Second-generation tooling was implemented using a bench scale rolling mill for continuous processing of sheet and bar. We have found that this design does not produce enough plastic strain per RCS cycle for effective grain refinement prior to the formation and growth of fatigue cracks. Third-generation tooling was designed to process sheet and increase the amount of shear deformation per iteration. The third-generation tooling design introduced significant shear strain and was found to be effective in grain refinement.}, number={1-2}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Huang, Jianyu and Zhu, Yuntian T. and Alexander, David J. and Liao, Xiaozhou and Lowe, Terry C. and Asaro, Robert J.}, year={2004}, month={Apr}, pages={35–39} }
 @article{huang_zhu_alexander_al._2004, title={Development of repetitive corrugation and straightening}, volume={371}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={HUANG, JY and ZHU, YT and ALEXANDER, DJ and al.}, year={2004}, pages={35–39} }
 @article{stolyarov_zhu_raab_zharikov_valiev_2004, title={Effect of initial microstructure on the microstructural evolution and mechanical properties of Ti during cold rolling}, volume={385}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/S0921-5093(04)00881-0}, DOI={10.1016/j.msea.2004.06.054}, abstractNote={Ultrafine-grained (UFG) Ti rods were produced via cold rolling UFG and coarse-grained (CG) Ti stocks. The initial UFG stock was produced via equal channel angular pressing. It was found that the initial UFG structure had beneficial influence on the mechanical properties of the cold-rolled Ti rods. Compared with Ti rods with initial CG microstructure, the Ti rods with the initial UFG microstructure have both higher strength and higher ductility after being cold rolled to varying strains. Transmission electron microscopy revealed that the Ti rods with the initial UFG microstructure had finer, more homogeneous microstructures after cold rolling. This study demonstrates the merit of UFG Ti processed by ECAP for further shaping and forming into structural components with superior mechanical properties.}, number={1-2}, journal={Materials Science and Engineering A}, publisher={Elsevier BV}, author={Stolyarov, V and Zhu, Y and Raab, G and Zharikov, A and Valiev, R}, year={2004}, month={Nov}, pages={309–313} }
 @article{stolyarov_zhu_raab_zharikov_valiev_2004, title={Effect of initial microstructure on the microstructural evolution and mechanical properties of Ti during cold rolling}, volume={385}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/S0921-5093(04)00881-0}, DOI={10.1016/S0921-5093(04)00881-0}, abstractNote={Ultrafine-grained (UFG) Ti rods were produced via cold rolling UFG and coarse-grained (CG) Ti stocks. The initial UFG stock was produced via equal channel angular pressing. It was found that the initial UFG structure had beneficial influence on the mechanical properties of the cold-rolled Ti rods. Compared with Ti rods with initial CG microstructure, the Ti rods with the initial UFG microstructure have both higher strength and higher ductility after being cold rolled to varying strains. Transmission electron microscopy revealed that the Ti rods with the initial UFG microstructure had finer, more homogeneous microstructures after cold rolling. This study demonstrates the merit of UFG Ti processed by ECAP for further shaping and forming into structural components with superior mechanical properties.}, number={1-2}, journal={Materials Science and Engineering A}, publisher={Elsevier BV}, author={Stolyarov, V and Zhu, Y and Raab, G and Zharikov, A and Valiev, R}, year={2004}, month={Nov}, pages={309–313} }
 @article{stolyarov_zhu_raab_al._2004, title={Effect of initial microstructure on the microstructural evolution and mechanical properties of Ti during cold rolling}, volume={385}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={STOLYAROV, VV and ZHU, YT and RAAB, GI and al.}, year={2004}, pages={309–313} }
 @article{berenov_serquis_liao_zhu_peterson_bugoslavsky_yates_blamire_cohen_macmanus-driscoll_2004, title={Enhancement of critical current density in low level Al-doped MgB2}, volume={17}, ISSN={0953-2048 1361-6668}, url={http://dx.doi.org/10.1088/0953-2048/17/10/001}, DOI={10.1088/0953-2048/17/10/001}, abstractNote={Two sets of MgB2 samples doped with up to 5 at.% of Al were prepared in different laboratories using different procedures. Decreases in the ‘a’ and ‘c’ lattice parameters were observed with Al doping, confirming Al substitution onto the Mg site. The critical temperature (Tc) remained largely unchanged with Al doping. For 1–2.5 at.% doping, at 20 K the in-field critical current densities (Jc s) were enhanced, particularly at lower fields. At 5 K, the in-field Jc was markedly improved; for example at 5 T Jc was enhanced by a factor of 20 for a doping level of 1 at.% Al. The improved Jcs correlate with increased sample resistivity, which is indicative of an increase in the upper critical field, Hc 2, through alloying.}, number={10}, journal={Superconductor Science and Technology}, publisher={IOP Publishing}, author={Berenov, A and Serquis, A and Liao, X Z and Zhu, Y T and Peterson, D E and Bugoslavsky, Y and Yates, K A and Blamire, M G and Cohen, L F and MacManus-Driscoll, J L}, year={2004}, month={Jul}, pages={1093–1096} }
 @article{berenov_serquis_liao_al._2004, title={Enhancement of critical current density in low level Al-doped MgB2}, volume={17}, number={10}, journal={SUPERCONDUCTOR SCIENCE & TECHNOLOGY}, author={BERENOV, A and SERQUIS, A and LIAO, XZ and al.}, year={2004}, pages={1093–1096} }
 @article{liao_srinivasan_zhao_al._2004, title={Formation mechanism of wide stacking faults in nanocrystalline Al}, volume={84}, DOI={10.1063/1.1734689}, abstractNote={A full dislocation often dissociates into two partial dislocations enclosing a stacking fault (SF) ribbon. The SF width significantly affects the mechanical behavior of metals. Al has very high stacking fault energy and, consequently, very narrow SF width in its coarse-grained state. We have found that some SFs in nanocrystalline Al are surprisingly 1.4–6.8 nm wide, which is 1.5–11 times higher than the reported experimental value in single crystal Al. Our analytical model shows that such wide SFs are formed due to the small grain size and possibly also to the interaction of SF ribbons with high density of dislocations.}, number={18}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and SRINIVASAN, SG and ZHAO, YH and al.}, year={2004}, pages={3564–3566} }
 @article{zhu_egeland_li_al._2004, title={Formation of pile networks by long carbon nanotubes from decomposition of CO on Co-Mo film}, volume={4}, number={1-2}, journal={JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY}, author={ZHU, YT and EGELAND, GW and LI, Y and al.}, year={2004}, pages={189–191} }
 @article{liao_zhao_zhu_valiev_gunderov_2004, title={Grain-size effect on the deformation mechanisms of nanostructured copper processed by high-pressure torsion}, volume={96}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.1757035}, DOI={10.1063/1.1757035}, abstractNote={The unique nonuniform deformation characteristic of high-pressure torsion was used to produce nanostructures with systematically varying grain sizes in a copper disk, which allows us to study the grain-size effect on the deformation mechanisms in nanostructured copper using a single sample. The as-processed copper disk has 100–200 nm grains near its center and 10–20 nm grains at its periphery. High densities of full dislocations (2×1016/m2) were distributed nonuniformly in large grains, implying that dislocation slip is the dominant deformation mechanism. With increasing dislocation density, the dislocations accumulated and rearranged, forming elongated nanodomains. The originally formed nanodomains remain almost the same crystalline orientation as their parent large grains. Further deformation occurred mainly through partial dislocation emissions from nanodomain boundaries, resulting in high density of nanotwins and stacking faults in the nanodomains. The elongated nanodomains finally transformed into equiaxed nanocrystalline grains with large-angle grain boundaries. The results suggest that grain boundary rotation and grain boundary sliding might play a significant role in the formation of large-angle grain boundaries in nanocrystalline grains. These experimental results show that different deformation mechanisms operate at different length scales and confirm unambiguously the deformation mechanisms of nanocrystalline grains predicted by molecular dynamic simulations.}, number={1}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Liao, X. Z. and Zhao, Y. H. and Zhu, Y. T. and Valiev, R. Z. and Gunderov, D. V.}, year={2004}, month={Jul}, pages={636–640} }
 @article{liao_zhao_zhu_al._2004, title={Grain-size effect on the deformation mechanisms of nanostructured copper processed by high-pressure torsion}, volume={96}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={LIAO, XZ and ZHAO, YH and ZHU, YT and al.}, year={2004}, pages={636–640} }
 @article{liao_sharma_wei_macmanus-driscoll_branford_cohen_bugoslavsky_zhu_peterson_jiang_et al._2004, title={Highly disordered intergrowths in Sr2 Fe Mo O6}, volume={96}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.1812585}, DOI={10.1063/1.1812585}, abstractNote={Two Sr2FeMoO6 samples, synthesized under different conditions and showing very different magnetotransport properties, were analyzed using transmission electron microscopy. The different magnetoresistive behaviors observed in the two samples coincide with the formation of different amounts of striped areas intergrown in the samples. The striped areas are comprised of a disordered and cation deficient phase, SrFe1−x−yMox−zO3−δ. The sample magnetization and magnetoresistance values decrease significantly with an increased presence of the striped phase. The striped phase was promoted by typical reducing formation conditions for Sr2FeMoO6 in Ar-1% H2 gas.}, number={12}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Liao, X. Z. and Sharma, A. and Wei, M. and MacManus-Driscoll, J. L. and Branford, W. and Cohen, L. F. and Bugoslavsky, Y. and Zhu, Y. T. and Peterson, D. E. and Jiang, Y. B. and et al.}, year={2004}, month={Dec}, pages={7747–7749} }
 @article{liao_sharma_wei_al._2004, title={Highly disordered intergrowths in Sr2FeMoO6}, volume={96}, number={12}, journal={JOURNAL OF APPLIED PHYSICS}, author={LIAO, XZ and SHARMA, A and WEI, M and al.}, year={2004}, pages={7747–7749} }
 @article{stan_zhu_jiang_butt_2004, title={Kinetics of oxygen removal from ceria}, volume={95}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.1650890}, DOI={10.1063/1.1650890}, abstractNote={The kinetics of oxygen removal from CeO2 were investigated using thermogravimetric analysis, at high temperatures, under a reducing atmosphere of Ar–6%H2. A chemical diffusivity model was developed that takes into account the composition dependence of both the pre-exponential factor and the activation energy. In this model, the pre-exponential factor is given by D0=22.32 exp(−0.22x) (cm2/s), and the activation energy is ΔE=195.4−173.9x (kJ/mol), where x is the nonstoichiometry coefficient in CeO2−x. The model describes well the oxygen removal kinetics for the entire time range (100 min), demonstrating its superiority over two popular mathematical models that can only fit part of the experimental data.}, number={7}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Stan, M. and Zhu, Y. T. and Jiang, H. and Butt, D. P.}, year={2004}, month={Apr}, pages={3358–3361} }
 @article{stan_zhu_jiang_al._2004, title={Kinetics of oxygen removal from ceria}, volume={95}, number={7}, journal={JOURNAL OF APPLIED PHYSICS}, author={STAN, M and ZHU, YT and JIANG, H and al.}, year={2004}, pages={3358–3361} }
 @article{serquis_civale_coulter_al._2004, title={Large field generation with a hot isostatically pressed powder-in-tube MgB2 coil at 25 K}, volume={17}, DOI={PII S0953-2048(04)78622-4}, number={10}, journal={SUPERCONDUCTOR SCIENCE & TECHNOLOGY}, author={SERQUIS, A and CIVALE, L and COULTER, JY and al.}, year={2004}, pages={L35–L37} }
 @article{serquis_civale_coulter_hammon_liao_zhu_peterson_mueller_nesterenko_indrakanti_2004, title={Large field generation with a hot isostatically pressed powder-in-tube MgB2 coil at 25 K}, volume={17}, ISSN={0953-2048 1361-6668}, url={http://dx.doi.org/10.1088/0953-2048/17/10/L01}, DOI={10.1088/0953-2048/17/10/L01}, abstractNote={We present the fabrication and test results of hot-isostatic-pressed (HIPed) powder-in-tube (PIT) MgB2 coils. The coils’ properties were measured by transport and magnetization at different applied fields (H) and temperatures (T). The engineering critical current (Je) value is the largest reported in PIT MgB2 wires or tapes. At 25 K our champion six-layer coil was able to generate a field of 1 T at zero external field (Ic>220 A, ). At 4 K this coil generated 1.6 T under an applied field of 1.25 T ( A, ). These magnetic fields are high enough for a superconducting transformer or magnet applications such as MRI. An SiC doped MgB2 single layer coil shows a promising improvement at high fields and exhibits Jc> 104 A cm−2 at 7 T.}, number={10}, journal={Superconductor Science and Technology}, publisher={IOP Publishing}, author={Serquis, A and Civale, L and Coulter, J Y and Hammon, D L and Liao, X Z and Zhu, Y T and Peterson, D E and Mueller, F M and Nesterenko, V F and Indrakanti, S S}, year={2004}, month={Jul}, pages={L35–L37} }
 @article{zhao_zhu_liu_2004, title={Mechanism of solid-state amorphization of Se induced by mechanical milling}, volume={95}, ISSN={0021-8979 1089-7550}, url={http://dx.doi.org/10.1063/1.1737478}, DOI={10.1063/1.1737478}, abstractNote={In this work, the solid-state amorphization process of elemental trigonal Se via mechanical milling was studied. Trigonal Se has a unique crystal structure consisting of helical [–Se–]n chains with strong intrachain covalent bonds and with weak interchain van der Waals bonds. It was found that the interchain coordination distance increased while the intrachain coordination distance decreased with increasing milling time. The crystalline Se transformed to the amorphous state once the interchain coordination distance reached a critical value. The intrachain coordination distance of amorphous Se continued to decrease with milling time, suggesting that molecular chain length decreased with milling time. Combined with the x-ray absorption near-edge structure calculations, it was concluded that the mechanical milling destroyed the interchain bonds of crystalline Se, resulting in the amorphization, while the intrachain bonds were strengthened during amorphization. The present results support a previous crystallite-destabilization model for solid-state amorphization.}, number={12}, journal={Journal of Applied Physics}, publisher={AIP Publishing}, author={Zhao, Y. H. and Zhu, Y. T. and Liu, T.}, year={2004}, month={Jun}, pages={7674–7680} }
 @article{zhao_liao_jin_valiev_zhu_2004, title={Microstructures and mechanical properties of ultrafine grained 7075 Al alloy processed by ECAP and their evolutions during annealing}, volume={52}, ISSN={1359-6454}, url={http://dx.doi.org/10.1016/j.actamat.2004.06.017}, DOI={10.1016/j.actamat.2004.06.017}, abstractNote={Microstructures and mechanical properties of equal-channel angular pressing (ECAP) processed and naturally aged ultrafine grained (UFG) and coarse grained (CG) 7075 Al alloys as well as their evolutions during annealing were investigated. After the same natural aging, the tensile yield strength, ultimate strength, and microhardness of the UFG samples were 103%, 35%, and 48% higher, respectively, than those of the CG samples, because of higher densities of Guinier–Preston (G–P) zones and dislocations in the UFG sample. Upon annealing, the microhardness of the UFG sample decreased gradually, while a hardening peak appeared for the CG sample. The peak was caused by the precipitation hardening of the metastable η′ phase. For the UFG sample, the precipitation hardening was overcompensated by the significant decrease of microstrain (dislocation density) upon annealing, resulting in a lack of precipitation hardening peak. Differential scanning calorimetry indicates that the ECAP process only accelerated the phase precipitations, but did not change the sequence of phase precipitation. This study shows that severe plastic deformation has the potential to significantly improve the mechanical properties of age-hardening Al alloys.}, number={15}, journal={Acta Materialia}, publisher={Elsevier BV}, author={Zhao, Y.H. and Liao, X.Z. and Jin, Z. and Valiev, R.Z. and Zhu, Y.T.}, year={2004}, month={Sep}, pages={4589–4599} }
 @article{zhao_liao_jin_al._2004, title={Microstructures and mechanical properties of ultrafine grained 7075 Al alloy processed by ECAP and their evolutions during annealing}, volume={52}, number={15}, journal={ACTA MATERIALIA}, author={ZHAO, YH and LIAO, XZ and JIN, Z and al.}, year={2004}, pages={4589–4599} }
 @article{zhu_liao_2004, title={Nanostructured metals - Retaining ductility}, volume={3}, number={6}, journal={NATURE MATERIALS}, author={ZHU, YT and LIAO, XZ}, year={2004}, pages={351–352} }
 @article{zhu_liao_srinivasan_zhao_baskes_zhou_lavernia_2004, title={Nucleation and growth of deformation twins in nanocrystalline aluminum}, volume={85}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1823042}, DOI={10.1063/1.1823042}, abstractNote={Deformation twins (DTs) in nanocrystalline (nc) Al were both predicted by atomic simulations, and observed experimentally. However, despite encouraging preliminary results, their formation mechanism remains poorly understood. Here we present an analytical model, based on classical dislocation theory, to explain the nucleation and growth of DTs in nc Al. A 60° dislocation system consisting of a 90° leading partial and a 30° trailing partial is found to most readily nucleate and grow a DT. The model suggests that the stress for twin growth is much smaller than that for its nucleation. It also predicts an optimal grain size for twin nucleation. The model successfully explains DTs observed experimentally in nc Al and is also applicable to other nc metals.}, number={21}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Zhu, Y. T. and Liao, X. Z. and Srinivasan, S. G. and Zhao, Y. H. and Baskes, M. I. and Zhou, F. and Lavernia, E. J.}, year={2004}, month={Nov}, pages={5049–5051} }
 @article{zhu_liao_srinivasan_al._2004, title={Nucleation and growth of deformation twins in nanocrystalline aluminum}, volume={85}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={ZHU, YT and LIAO, XZ and SRINIVASAN, SG and al.}, year={2004}, pages={5049–5051} }
 @article{zhu_lowe_langdon_2004, title={Performance and applications of nanostructured materials produced by severe plastic deformation}, volume={51}, ISSN={1359-6462}, url={http://dx.doi.org/10.1016/j.scriptamat.2004.05.006}, DOI={10.1016/j.scriptamat.2004.05.006}, abstractNote={Nanostructured materials produced by severe plastic deformation can be tailored to have both superior performance and superior properties. These materials are attractive for use in a range of applications from biomedical to aerospace industries.}, number={8}, journal={Scripta Materialia}, publisher={Elsevier BV}, author={Zhu, Yuntian T and Lowe, Terry C and Langdon, Terence G}, year={2004}, month={Oct}, pages={825–830} }
 @article{liao_zhu_qiu_uhl_xu_2004, title={Quantum dot/substrate interaction in InAs/In0.53 Ga0.47 As/InP(001)}, volume={84}, ISSN={0003-6951 1077-3118}, url={http://dx.doi.org/10.1063/1.1642754}, DOI={10.1063/1.1642754}, abstractNote={InAs quantum dots grown on In0.53Ga0.47As/InP(001) substrate by low-pressure metalorganic chemical vapor deposition were investigated using high-angle annular dark-field imaging. Results suggest significant mass transport of mainly the large-sized component (InAs) from the In0.53Ga0.47As substrate to InAs quantum dots, an unexpected process that increases the system strain energy. The amount of the transported mass increases with quantum dot size. Two monolayers of GaAs inserted between InAs islands and the InGaAs substrate appears to block or at least effectively slow down this mass transport process.}, number={4}, journal={Applied Physics Letters}, publisher={AIP Publishing}, author={Liao, X. Z. and Zhu, Y. T. and Qiu, Y. M. and Uhl, D. and Xu, H. F.}, year={2004}, month={Jan}, pages={511–513} }
 @article{liao_zhu_qiu_al._2004, title={Quantum dot/substrate interaction in InAs/In0.53Ga0.47As/InP(001)}, volume={84}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and ZHU, YT and QIU, YM and al.}, year={2004}, pages={511–513} }
 @article{stolyarov_shuster_migranov_valiev_zhu_2004, title={Reduction of friction coefficient of ultrafine-grained CP titanium}, volume={371}, ISSN={0921-5093}, url={http://dx.doi.org/10.1016/j.msea.2003.12.026}, DOI={10.1016/j.msea.2003.12.026}, abstractNote={Friction coefficient is an important material property that affects the performance and service life of structural components that slide against each other. The frictional force consists of an adhesion force and a deformation force, producing an adhesion component and a deformation component of the friction coefficient. In this study, we compare the adhesion components of ultrafine-grained (UFG) Ti and coarse-grained (CG) Ti at temperatures from 25 to 800 °C and under a range of pressures. The UFG Ti samples were in two processing states: equal channel angular pressing (ECAP) for eight passes and ECAP+further cold rolling for 75% rolling strain. The experimental data indicate that ultrafine-grained structure results in lower adhesion component and consequently lower friction coefficient, which should in turn improve the wear property.}, number={1-2}, journal={Materials Science and Engineering: A}, publisher={Elsevier BV}, author={Stolyarov, V.V. and Shuster, L.Sh. and Migranov, M.Sh. and Valiev, R.Z. and Zhu, Y.T.}, year={2004}, month={Apr}, pages={313–317} }
 @article{stolyarov_shuster_migranov_al._2004, title={Reduction of friction coefficient of ultrafine-grained CP titanium}, volume={371}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={STOLYAROV, VV and SHUSTER, LS and MIGRANOV, MS and al.}, year={2004}, pages={313–317} }
 @article{zhu_liao_2004, title={Retaining ductility}, volume={3}, ISSN={1476-1122 1476-4660}, url={http://dx.doi.org/10.1038/nmat1141}, DOI={10.1038/nmat1141}, number={6}, journal={Nature Materials}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian T. and Liao, Xiaozhou}, year={2004}, month={Jun}, pages={351–352} }
 @article{liao_serquis_zhu_peterson_mueller_xu_2004, title={Strain effect on the critical superconducting temperature of MgB2}, volume={17}, ISSN={0953-2048 1361-6668}, url={http://dx.doi.org/10.1088/0953-2048/17/8/014}, DOI={10.1088/0953-2048/17/8/014}, abstractNote={MgB2 samples synthesized by solid-state reaction were found to contain several types of crystalline defects, including Mg deficiency, coherent precipitates, screw dislocations, and oxygen impurity, depending on the synthesis conditions. The Mg deficiency introduced significant strain in the crystalline lattice of MgB2. A high density of screw dislocations lying on (0001) planes with a Burgers vector of partially relieved the lattice strain. The remnant strain in the MgB2 lattice directly determines the critical superconducting temperature, which decreases with strain. A small amount of oxygen dissolved in the MgB2 matrix is not responsible for lowering Tc observed in our samples.}, number={8}, journal={Superconductor Science and Technology}, publisher={IOP Publishing}, author={Liao, X Z and Serquis, A and Zhu, Y T and Peterson, D E and Mueller, F M and Xu, H F}, year={2004}, month={Jun}, pages={1026–1030} }
 @article{liao_serquis_zhu_al._2004, title={Strain effect on the critical superconducting temperature of MgB2}, volume={17}, number={8}, journal={SUPERCONDUCTOR SCIENCE & TECHNOLOGY}, author={LIAO, XZ and SERQUIS, A and ZHU, YT and al.}, year={2004}, pages={1026–1030} }
 @article{zhu_langdon_2004, title={The fundamentals of nanostructured materials processed by severe plastic deformation}, volume={56}, ISSN={1047-4838 1543-1851}, url={http://dx.doi.org/10.1007/S11837-004-0294-0}, DOI={10.1007/S11837-004-0294-0}, number={10}, journal={JOM}, publisher={Springer Science and Business Media LLC}, author={Zhu, Yuntian T. and Langdon, Terence G.}, year={2004}, month={Oct}, pages={58–63} }
 @article{wang_ma_valiev_zhu_2004, title={Tough Nanostructured Metals at Cryogenic Temperatures}, volume={16}, ISSN={0935-9648 1521-4095}, url={http://dx.doi.org/10.1002/adma.200305679}, DOI={10.1002/adma.200305679}, abstractNote={Copper, titanium, and iron with grain sizes of the order of 100 nm were prepared by severe plastic deformation. At 77 K these materials offer very high yield strength coupled with high ductility, uniform tensile strains, and long‐term stability. These properties demonstrate a nanomaterials advantage for science and engineering endeavors that employ or encounter cryogenic temperatures. The Figure shows ductile deformation in the nanostructured Fe.}, number={4}, journal={Advanced Materials}, publisher={Wiley}, author={Wang, Y. M. and Ma, E. and Valiev, R. Z. and Zhu, Y. T.}, year={2004}, month={Feb}, pages={328–331} }
 @article{wang_ma_valiev_al._2004, title={Tough nanostructured metals at cryogenic temperatures}, volume={16}, number={4}, journal={ADVANCED MATERIALS}, author={WANG, YM and MA, E and VALIEV, RZ and al.}, year={2004}, pages={328-+} }
 @article{zheng_o'connell_doorn_liao_zhao_akhadov_hoffbauer_roop_jia_dye_et al._2004, title={Ultralong single-wall carbon nanotubes}, volume={3}, ISSN={1476-1122 1476-4660}, url={http://dx.doi.org/10.1038/nmat1216}, DOI={10.1038/nmat1216}, abstractNote={Since the discovery of carbon nanotubes in 1991 by Iijima1, there has been great interest in creating long, continuous nanotubes for applications where their properties coupled with extended lengths will enable new technology developments2. For example, ultralong nanotubes can be spun into fibres that are more than an order of magnitude stronger than any current structural material, allowing revolutionary advances in lightweight, high-strength applications3. Long metallic nanotubes will enable new types of micro-electromechanical systems such as micro-electric motors, and can also act as a nanoconducting cable for wiring micro-electronic devices4. Here we report the synthesis of 4-cm-long individual single-wall carbon nanotubes (SWNTs) at a high growth rate of 11 μm s−1 by catalytic chemical vapour deposition. Our results suggest the possibility of growing SWNTs continuously without any apparent length limitation.}, number={10}, journal={Nature Materials}, publisher={Springer Science and Business Media LLC}, author={Zheng, L. X. and O'Connell, M. J. and Doorn, S. K. and Liao, X. Z. and Zhao, Y. H. and Akhadov, E. A. and Hoffbauer, M. A. and Roop, B. J. and Jia, Q. X. and Dye, R. C. and et al.}, year={2004}, month={Sep}, pages={673–676} }
 @article{zheng_o’connell_doorn_al._2004, title={Ultralong single-wall carbon nanotubes}, volume={3}, number={10}, journal={NATURE MATERIALS}, author={ZHENG, LX and O’CONNELL, MJ and DOORN, SK and al.}, year={2004}, pages={673–676} }
 @article{gubicza_dragomir_ribarik_al._2003, title={Characterization of the microstructure of severely deformed titanium by X-ray diffraction profile analysis}, volume={414-4}, journal={MATERIALS SCIENCE, TESTING AND INFORMATICS}, author={GUBICZA, J and DRAGOMIR, LC and RIBARIK, G and al.}, year={2003}, pages={229–234} }
 @article{serquis_liao_huang_al._2003, title={Co-Mo catalyzed growth of multi-wall carbon nanotubes from CO decomposition}, volume={41}, number={13}, journal={CARBON}, author={SERQUIS, A and LIAO, XZ and HUANG, JY and al.}, year={2003}, pages={2635–2641} }
 @article{lowe_zhu_2003, title={Commercialization of nanostructured metals produced by severe plastic deformation processing}, volume={5}, number={5}, journal={ADVANCED ENGINEERING MATERIALS}, author={LOWE, TC and ZHU, YT}, year={2003}, pages={373–378} }
 @article{liao_serquis_zhu_al._2003, title={Defect structures in MgB2 wires introduced by hot isostatic pressing}, volume={16}, number={7}, journal={SUPERCONDUCTOR SCIENCE & TECHNOLOGY}, author={LIAO, XZ and SERQUIS, A and ZHU, YT and al.}, year={2003}, pages={799–803} }
 @article{liao_zhou_lavernia_al._2003, title={Deformation mechanism in nanocrystalline Al: Partial dislocation slip}, volume={83}, number={4}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and ZHOU, F and LAVERNIA, EJ and al.}, year={2003}, pages={632–634} }
 @article{liao_zhou_lavernia_al._2003, title={Deformation twins in nanocrystalline Al}, volume={83}, number={24}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and ZHOU, F and LAVERNIA, EJ and al.}, year={2003}, pages={5062–5064} }
 @article{kim_kim_shin_al._2003, title={Deformation twins in pure titanium processed by equal channel angular pressing}, volume={48}, number={6}, journal={SCRIPTA MATERIALIA}, author={KIM, I and KIM, J and SHIN, DH and al.}, year={2003}, pages={813–817} }
 @article{gubicza_dragomir_ribarik_al._2003, title={Dislocation structure and crystallite size distribution in plastically deformed Ti determined by X-ray peak profile analysis}, volume={94}, number={11}, journal={ZEITSCHRIFT FUR METALLKUNDE}, author={GUBICZA, J and DRAGOMIR, IC and RIBARIK, G and al.}, year={2003}, pages={1185–1188} }
 @article{liao_serquis_jia_al._2003, title={Effect of catalyst composition on carbon nanotube growth}, volume={82}, number={16}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and SERQUIS, A and JIA, QX and al.}, year={2003}, pages={2694–2696} }
 @article{huang_liao_zhu_zhou_lavernia_2003, title={Grain boundary structure of nanocrystalline Cu processed by cryomilling}, volume={83}, ISSN={1478-6435 1478-6443}, url={http://dx.doi.org/10.1080/1478643031000083633}, DOI={10.1080/1478643031000083633}, abstractNote={The microstructures of cryogenically ball-milled Cu were investigated by high-resolution electron microscopy. It was found that the grain-size reduction is a dislocation-controlled continuous process which consists of the formation of small-angle grain boundaries (GBs), a gradual increase in misorientations as a result of accumulation of more dislocations and, finally, the formation of large-angle GBs. The GBs were generally curved, wavy or faceted, and heavily strained, which are typical characteristics of nanostructured materials. In addition, extrinsic dislocations were found in many GBs, indicating that most are in a high-energy non-equilibrium configuration, which is consistent with observations in equal-channel angular pressing processed Cu, Ni, and Al-Mg, repetitive corrugation and straightening processed Cu and room-temperature ball-milled Cu. These results support a still-disputed concept that GBs in nanostructured metals processed by severe plastic deformation are mostly in non-equilibrium states.}, number={12}, journal={Philosophical Magazine}, publisher={Informa UK Limited}, author={Huang, J. Y. and Liao, X. Z. and Zhu, Y. T. and Zhou, F. and Lavernia, E. J.}, year={2003}, month={Jan}, pages={1407–1419} }
 @article{huang_liao_zhu_al._2003, title={Grain boundary structure of nanocrystalline Cu processed by cryomilling}, volume={83}, number={12}, journal={PHILOSOPHICAL MAGAZINE}, author={HUANG, JY and LIAO, XZ and ZHU, YT and al.}, year={2003}, pages={1407–1419} }
 @article{stolyarov_zhu_alexandrov_al._2003, title={Grain refinement and properties of pure Ti processed by warm ECAP and cold rolling}, volume={343}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={STOLYAROV, VV and ZHU, YT and ALEXANDROV, IV and al.}, year={2003}, pages={43–50} }
 @article{civale_serquis_hammon_al._2003, title={High critical currents in powder in tube MgB2 wires: Influence of microstructure and heat treatments}, volume={13}, number={2}, journal={IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY}, author={CIVALE, L and SERQUIS, A and HAMMON, DL and al.}, year={2003}, pages={3347–3350} }
 @article{serquis_civale_hammon_al._2003, title={Hot isostatic pressing of powder in tube MgB2 wires}, volume={82}, number={17}, journal={APPLIED PHYSICS LETTERS}, author={SERQUIS, A and CIVALE, L and HAMMON, DL and al.}, year={2003}, pages={2847–2849} }
 @article{zhu_beyerlein_2003, title={Issues on the design of bone-shaped short fiber composites}, volume={35}, number={2}, journal={JOURNAL OF ADVANCED MATERIALS}, author={ZHU, YT and BEYERLEIN, IJ}, year={2003}, pages={51–60} }
 @article{he_chung_liao_al._2003, title={Mechanical milling-induced deformation twinning in Fcc materials with high stacking fault energy}, volume={34}, number={3}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={HE, JH and CHUNG, KH and LIAO, XZ and al.}, year={2003}, pages={707–712} }
 @article{liao_serquis_zhu_al._2003, title={Mg(B,O)(2) precipitation in MgB2}, volume={93}, number={10}, journal={JOURNAL OF APPLIED PHYSICS}, author={LIAO, XZ and SERQUIS, A and ZHU, YT and al.}, year={2003}, pages={6208–6215} }
 @article{zhou_liao_zhu_al._2003, title={Microstructural evolution during recovery and recrystallization of a nanocrystalline Al-Mg alloy prepared by cryogenic ball milling}, volume={51}, number={10}, journal={ACTA MATERIALIA}, author={ZHOU, F and LIAO, XZ and ZHU, YT and al.}, year={2003}, pages={2777–2791} }
 @article{serquis_civale_hammon_al._2003, title={Microstructure and high critical current of powder-in-tube MgB2}, volume={82}, number={11}, journal={APPLIED PHYSICS LETTERS}, author={SERQUIS, A and CIVALE, L and HAMMON, DL and al.}, year={2003}, pages={1754–1756} }
 @article{huang_zhu_liao_al._2003, title={Microstructure of cryogenic treated M2 tool steel}, volume={339}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={HUANG, JY and ZHU, YT and LIAO, XZ and al.}, year={2003}, pages={241–244} }
 @article{zhu_kolobov_grabovetskaya_al._2003, title={Microstructures and mechanical properties of ultrafine-grained Ti foil processed by equal-channel angular pressing and cold rolling}, volume={18}, number={4}, journal={JOURNAL OF MATERIALS RESEARCH}, author={ZHU, YT and KOLOBOV, YR and GRABOVETSKAYA, GP and al.}, year={2003}, pages={1011–1016} }
 @article{findikoglu_serquis_civale_al._2003, title={Microwave performance of high-density bulk MgB2}, volume={83}, number={1}, journal={APPLIED PHYSICS LETTERS}, author={FINDIKOGLU, AT and SERQUIS, A and CIVALE, L and al.}, year={2003}, pages={108–110} }
 @article{liao_huang_zhu_zhou_lavernia_2003, title={Nanostructures and deformation mechanisms in a cryogenically ball-milled Al-Mg alloy}, volume={83}, ISSN={1478-6435 1478-6443}, url={http://dx.doi.org/10.1080/1478643031000152799}, DOI={10.1080/1478643031000152799}, abstractNote={An Al-7.6 at.% Mg alloy was ball milled in liquid N2 for 8 h and its microstructures were investigated using transmission electron microscopy. Electron diffraction confirmed that the resulting powder is a supersaturated Al-Mg solid solution with an fcc structure. Three typical nanostructures with different grain-size ranges and shapes were observed and the deformation mechanisms in these structures were found to be different. High densities of dislocations were found in large crystallites, implying that dislocation slip is the dominant deformation mechanism. The dislocations rearranged to form small-angle subboundaries upon further deformation, resulting in the formation of medium-sized crystallites with diameters of 10-30 nm. In very small crystallites with dimensions less than 10 nm, twinning becomes an important deformation mechanism. The reasons for the different deformation mechanisms were discussed. Some defects, such as twin boundaries, and small- and large-angle grain boundaries were investigated in detail.}, number={26}, journal={Philosophical Magazine}, publisher={Informa UK Limited}, author={Liao, X. Z. and Huang, J. Y. and Zhu, Y. T. and Zhou, F. and Lavernia, E. J.}, year={2003}, month={Sep}, pages={3065–3075} }
 @article{liao_huang_zhu_al._2003, title={Nanostructures and deformation mechanisms in a cryogenically ball-milled Al-Mg alloy}, volume={83}, number={26}, journal={PHILOSOPHICAL MAGAZINE}, author={LIAO, XZ and HUANG, JY and ZHU, YT and al.}, year={2003}, pages={3065–3075} }
 @article{zhu_huang_gubicza_al._2003, title={Nanostructures in Ti processed by severe plastic deformation}, volume={18}, number={8}, journal={JOURNAL OF MATERIALS RESEARCH}, author={ZHU, YT and HUANG, JY and GUBICZA, J and al.}, year={2003}, pages={1908–1917} }
 @article{serquis_civale_hammon_al._2003, title={Role of excess Mg and heat treatments on microstructure and critical current of MgB2 wires}, volume={94}, number={6}, journal={JOURNAL OF APPLIED PHYSICS}, author={SERQUIS, A and CIVALE, L and HAMMON, DL and al.}, year={2003}, pages={4024–4031} }
 @article{serquis_liao_civale_al._2003, title={The influence of structural defects on intra-granular critical currents of bulk MgB2}, volume={13}, number={2}, journal={IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY}, author={SERQUIS, A and LIAO, XZ and CIVALE, L and al.}, year={2003}, pages={3068–3071} }
 @article{huang_zhu_2002, title={Atomic-scale structural investigations on the nucleation of cubic boron nitride from amorphous boron nitride under high pressures and temperatures}, volume={14}, number={4}, journal={CHEMISTRY OF MATERIALS}, author={HUANG, JY and ZHU, YT}, year={2002}, pages={1873–1878} }
 @article{zhu_beyerlein_2002, title={Bone-shaped short fiber composites - an overview}, volume={326}, number={2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHU, YT and BEYERLEIN, IJ}, year={2002}, pages={208–227} }
 @article{liao_serquis_zhu_al._2002, title={Controlling flux pinning precipitates during MgB2 synthesis}, volume={80}, number={23}, journal={APPLIED PHYSICS LETTERS}, author={LIAO, XZ and SERQUIS, AC and ZHU, YT and al.}, year={2002}, pages={4398–4400} }
 @article{serquis_zhu_peterson_al._2002, title={Degradation of MgB2 under ambient environment}, volume={80}, number={23}, journal={APPLIED PHYSICS LETTERS}, author={SERQUIS, A and ZHU, YT and PETERSON, DE and al.}, year={2002}, pages={4401–4403} }
 @article{huang_park_jan_al._2002, title={High-resolution transmission electron microscopy study of defects and interfaces in epitaxial TiO2 films on sapphire and LaAlO3}, volume={82}, number={4}, journal={PHILOSOPHICAL MAGAZINE A-PHYSICS OF CONDENSED MATTER STRUCTURE DEFECTS AND MECHANICAL PROPERTIES}, author={HUANG, JY and PARK, BH and JAN, D and al.}, year={2002}, pages={735–749} }
 @article{serquis_liao_zhu_al._2002, title={Influence of microstructures and crystalline defects on the superconductivity of MgB2}, volume={92}, number={1}, journal={JOURNAL OF APPLIED PHYSICS}, author={SERQUIS, A and LIAO, XZ and ZHU, YT and al.}, year={2002}, pages={351–356} }
 @article{zhu_shu_butt_2002, title={Kinetics and products of molybdenum disilicide powder oxidation}, volume={85}, number={2}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={ZHU, YT and SHU, L and BUTT, DP}, year={2002}, pages={507–509} }
 @article{klie_idrobo_browning_al._2002, title={Observation of coherent oxide precipitates in polycrystalline MgB2}, volume={80}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={KLIE, RF and IDROBO, JC and BROWNING, ND and al.}, year={2002}, pages={3970–3972} }
 @article{valiev_alexandrov_zhu_al._2002, title={Paradox of strength and ductility in metals processed by severe plastic deformation}, volume={17}, number={1}, journal={JOURNAL OF MATERIALS RESEARCH}, author={VALIEV, RZ and ALEXANDROV, IV and ZHU, YT and al.}, year={2002}, pages={5–8} }
 @article{zhu_shu_peterson_al._2002, title={Rietveld refinement of crystal chemistry of RBa4Cu3O8.5+delta (R = rare earth)}, volume={63}, number={1}, journal={JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS}, author={ZHU, YT and SHU, L and PETERSON, EJ and al.}, year={2002}, pages={23–29} }
 @article{shin_kim_kim_al._2002, title={Shear strain accommodation during severe plastic deformation of titanium using equal channel angular pressing}, volume={334}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={SHIN, DH and KIM, I and KIM, J and al.}, year={2002}, pages={239–245} }
 @article{zhao_he_daemen_al._2002, title={Superhard B-C-N materials synthesized in nanostructured bulks}, volume={17}, number={12}, journal={JOURNAL OF MATERIALS RESEARCH}, author={ZHAO, Y and HE, DW and DAEMEN, LL and al.}, year={2002}, pages={3139–3145} }
 @article{zhu_jiang_huang_al._2001, title={A new route to bulk nanostructured metals}, volume={32}, number={6}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={ZHU, YT and JIANG, HG and HUANG, JY and al.}, year={2001}, pages={1559–1562} }
 @article{jia_wang_ramesh_al._2001, title={Deformation behavior and plastic instabilities of ultrafine-grained titanium}, volume={79}, number={5}, journal={APPLIED PHYSICS LETTERS}, author={JIA, D and WANG, YM and RAMESH, KT and al.}, year={2001}, pages={611–613} }
 @article{serquis_zhu_peterson_al._2001, title={Effect of lattice strain and defects on the superconductivity of MgB2}, volume={79}, number={26}, journal={APPLIED PHYSICS LETTERS}, author={SERQUIS, A and ZHU, YT and PETERSON, EJ and al.}, year={2001}, pages={4399–4401} }
 @article{zhu_beyerlein_valdez_al._2001, title={Fracture toughness of a composite reinforced with bone-shaped short fibers}, volume={317}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHU, YT and BEYERLEIN, IJ and VALDEZ, JA and al.}, year={2001}, pages={93–100} }
 @article{stolyarov_zhu_alexandrov_al._2001, title={Influence of ECAP routes on the microstructure and properties of pure Ti}, volume={299}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={STOLYAROV, VV and ZHU, YT and ALEXANDROV, IV and al.}, year={2001}, pages={59–67} }
 @article{stolyarov_zhu_lowe_al._2001, title={Microstructure and properties of pure Ti processed by ECAP and cold extrusion}, volume={303}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={STOLYAROV, VV and ZHU, YT and LOWE, TC and al.}, year={2001}, pages={82–89} }
 @article{huang_zhu_jiang_al._2001, title={Microstructures and dislocation configurations in nanostructured Cu processed by repetitive corrugation and straightening}, volume={49}, number={9}, journal={ACTA MATERIALIA}, author={HUANG, JY and ZHU, YT and JIANG, H and al.}, year={2001}, pages={1497–1505} }
 @article{stolyarov_zhu_lowe_al._2001, title={Microstructures and properties of ultrafine-grained pure titanium processed by equal-channel angular pressing and cold deformation}, volume={1}, number={2}, journal={JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY}, author={STOLYAROV, VV and ZHU, YT and LOWE, TC and al.}, year={2001}, pages={237–242} }
 @article{beyerlein_zhu_mahesh_2001, title={On the influence of fiber shape in bone-shaped short-fiber composites}, volume={61}, number={10}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={BEYERLEIN, IJ and ZHU, YT and MAHESH, S}, year={2001}, pages={1341–1357} }
 @article{huang_zhu_mori_2001, title={Structure and phase characteristics of amorphous boron-carbon-nitrogen under high pressure and high temperature}, volume={16}, number={4}, journal={JOURNAL OF MATERIALS RESEARCH}, author={HUANG, JY and ZHU, YT and MORI, H}, year={2001}, pages={1178–1184} }
 @article{huang_zhu_2000, title={Advances in the synthesis and characterization of boron nitride}, volume={186-1}, journal={DEFECTS AND DIFFUSION IN CERAMICS}, author={HUANG, JY and ZHU, YT}, year={2000}, pages={1–32} }
 @article{zhu_lowe_2000, title={Application of, and precautions for the use of, the rule of additivity in phase transformation}, volume={31}, number={4}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE}, author={ZHU, YT and LOWE, TC}, year={2000}, pages={675–682} }
 @article{wang_romero_mattes_al._2000, title={Effect of processing conditions on the properties of high molecular weight conductive polyaniline fiber}, volume={38}, number={1}, journal={JOURNAL OF POLYMER SCIENCE PART B-POLYMER PHYSICS}, author={WANG, HL and ROMERO, RJ and MATTES, BR and al.}, year={2000}, pages={194–204} }
 @article{jiang_zhu_butt_al._2000, title={Microstructural evolution, microhardness and thermal stability of HPT-processed Cu}, volume={290}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={JIANG, HG and ZHU, YT and BUTT, DP and al.}, year={2000}, pages={128–138} }
 @article{zhu_lowe_2000, title={Observations and issues on mechanisms of grain refinement during ECAP process}, volume={291}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={ZHU, YT and LOWE, TC}, year={2000}, pages={46–53} }
 @inbook{overview and outlook for materials processed by severe plastic deformation_2000, volume={80}, booktitle={Investigations and Applications of Severe Plastic Deformation}, year={2000}, pages={347–356} }
 @article{stolyarov_zhu_lowe_al._2000, title={Processing nanocrystalline Ti and its nanocomposites from micrometer-sized Ti powder using high pressure torsion}, volume={282}, number={1-2}, journal={MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING}, author={STOLYAROV, VV and ZHU, YT and LOWE, TC and al.}, year={2000}, pages={78–85} }
 @article{jiang_valdez_zhu_al._2000, title={The strength and toughness of cement reinforced with bone-shaped steel wires}, volume={60}, number={9}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={JIANG, HG and VALDEZ, JA and ZHU, YT and al.}, year={2000}, pages={1753–1761} }
 @article{stolyarov_zhu_lowe_al._1999, title={A two step SPD processing of ultrafine-grained titanium}, volume={11}, number={7}, journal={NANOSTRUCTURED MATERIALS}, author={STOLYAROV, VV and ZHU, YT and LOWE, TC and al.}, year={1999}, pages={947–954} }
 @article{zhu_baldonado_bingert_al._1999, title={Compressive anneal processing (CAP) of Bi2223 superconducting tapes}, volume={12}, number={9}, journal={SUPERCONDUCTOR SCIENCE & TECHNOLOGY}, author={ZHU, YT and BALDONADO, PS and BINGERT, JF and al.}, year={1999}, pages={640–644} }
 @article{stolyarov_shestakova_zhu_al._1999, title={Formation of metastable states in nanostructured Al- and Ti -based alloys by the SPTS technique}, volume={12}, number={5-8}, journal={NANOSTRUCTURED MATERIALS}, author={STOLYAROV, VV and SHESTAKOVA, LO and ZHU, YT and al.}, year={1999}, pages={923–926} }
 @article{zhu_valdez_beyerlein_al._1999, title={Mechanical properties of bone-shaped-short-fiber reinforced composites}, volume={47}, number={6}, journal={ACTA MATERIALIA}, author={ZHU, YT and VALDEZ, JA and BEYERLEIN, IJ and al.}, year={1999}, pages={1767–1781} }
 @article{jiang_zhu_butt_1999, title={Oxidation kinetics of hexagonal-shaped single-crystal silicon whiskers}, volume={82}, number={10}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={JIANG, HG and ZHU, YT and BUTT, DP}, year={1999}, pages={2791–2795} }
 @article{zhu_peterson_baldonado_al._1999, title={Synthesis and crystal chemistry of the new compounds GdBa4Cu3O8.5+delta and DyBa4Cu3O8.5+delta}, volume={14}, number={2}, journal={JOURNAL OF MATERIALS RESEARCH}, author={ZHU, YT and PETERSON, EJ and BALDONADO, PS and al.}, year={1999}, pages={334–339} }
 @article{zhu_stan_conzone_al._1999, title={Thermal oxidation kinetics of MoSi2-based powders}, volume={82}, number={10}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={ZHU, YT and STAN, M and CONZONE, SD and al.}, year={1999}, pages={2785–2790} }
 @article{zhu_valdez_shi_al._1998, title={A composite reinforced with bone-shaped short fibers}, volume={38}, number={9}, journal={SCRIPTA MATERIALIA}, author={ZHU, YT and VALDEZ, JA and SHI, N and al.}, year={1998}, pages={1321–1325} }
 @article{taylor_zhu_blumenthal_al._1998, title={Characterization of Nicalon fibres with varying diameters - Part I - Strength and fracture studies}, volume={33}, number={6}, journal={JOURNAL OF MATERIALS SCIENCE}, author={TAYLOR, ST and ZHU, YT and BLUMENTHAL, WR and al.}, year={1998}, pages={1465–1473} }
 @article{zhu_taylor_stout_al._1998, title={Characterization of Nicalon fibres with varying diameters - Part II - Modified Weibull distribution}, volume={33}, number={6}, journal={JOURNAL OF MATERIALS SCIENCE}, author={ZHU, YT and TAYLOR, ST and STOUT, MG and al.}, year={1998}, pages={1475–1480} }
 @article{alexandrov_zhu_lowe_al._1998, title={Consolidation of nanometer sized powders using severe plastic torsional straining}, volume={10}, number={1}, journal={NANOSTRUCTURED MATERIALS}, author={ALEXANDROV, IV and ZHU, YT and LOWE, TC and al.}, year={1998}, pages={45–54} }
 @article{zhu_peterson_baldonado_al._1998, title={Crystal structure and chemistry of four new RBa4Cu3O8.5+delta (R = Ho, Er, Tm and Yb) compounds}, volume={281}, number={2}, journal={JOURNAL OF ALLOYS AND COMPOUNDS}, author={ZHU, YT and PETERSON, EJ and BALDONADO, PS and al.}, year={1998}, pages={137–145} }
 @article{zhu_butt_taylor_al._1998, title={Evaluation of a modified Weibull distribution for describing the strength of ceramic fibers and whiskers with varying diameters}, volume={26}, number={2}, journal={JOURNAL OF TESTING AND EVALUATION}, author={ZHU, YT and BUTT, DP and TAYLOR, ST and al.}, year={1998}, pages={144–150} }
 @book{zhu_valdez_shi_lovato_stout_zhou_blumenthal_lowe_1998, title={Influence of reinforcement morphology on the mechanical properties of short-fiber composites}, journal={Processing of Metals and Advanced Materials: Modeling, Design and Properties}, author={Zhu, YT and Valdez, JA and Shi, N and Lovato, ML and Stout, MG and Zhou, SJ and Blumenthal, WR and Lowe, TC}, year={1998}, pages={251–259} }
 @article{zhu_taylor_stout_al._1998, title={Kinetics of thermal, passive oxidation of Nicalon fibers}, volume={81}, number={3}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={ZHU, YT and TAYLOR, ST and STOUT, MG and al.}, year={1998}, pages={655–660} }
 @article{alexandrov_zhu_lowe_al._1998, title={Microstructures and properties of nanocomposites obtained through SPTS consolidation of powders}, volume={29}, number={9}, journal={METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={ALEXANDROV, IV and ZHU, YT and LOWE, TC and al.}, year={1998}, pages={2253–2260} }
 @article{alexandrov_zhu_lowe_al._1998, title={Severe plastic deformation: new technique for powder consolidation and grain size refinement}, volume={41}, number={1}, journal={POWDER METALLURGY}, author={ALEXANDROV, IV and ZHU, YT and LOWE, TC and al.}, year={1998}, pages={11–13} }
 @article{zhu_peterson_baldonado_al._1998, title={Synthesis and characterization of the new compound EuBa4Cu3O8.5+delta}, volume={59}, number={8}, journal={JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS}, author={ZHU, YT and PETERSON, EJ and BALDONADO, PS and al.}, year={1998}, pages={1331–1336} }
 @article{zhu_baldonado_peterson_al._1998, title={Variation of oxygen content and crystal chemistry of YBa4Cu3O8.5+delta}, volume={298}, number={1-2}, journal={PHYSICA C}, author={ZHU, YT and BALDONADO, PS and PETERSON, EJ and al.}, year={1998}, pages={29–36} }
 @article{zhu_blumenthal_taylor_al._1997, title={Analysis of size dependence of ceramic fiber and whisker strength}, volume={80}, number={6}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={ZHU, YT and BLUMENTHAL, WR and TAYLOR, ST and al.}, year={1997}, pages={1447–1452} }
 @article{zhu_lowe_asaro_1997, title={Assessment of the theoretical basis of the Rule of Additivity for the nucleation incubation time during continuous cooling}, volume={82}, number={3}, journal={JOURNAL OF APPLIED PHYSICS}, author={ZHU, YT and LOWE, TC and ASARO, RJ}, year={1997}, pages={1129–1137} }
 @article{zhu_blumenthal_lowe_1997, title={Determination of non-symmetric 3-D fiber-orientation distribution and average fiber length in short-fiber composites}, volume={31}, number={13}, journal={JOURNAL OF COMPOSITE MATERIALS}, author={ZHU, YT and BLUMENTHAL, WR and LOWE, TC}, year={1997}, pages={1287–1301} }
 @article{mattes_wang_yang_al._1997, title={Formation of conductive polyaniline fibers derived from highly concentrated emeraldine base solutions}, volume={84}, number={1-3}, journal={SYNTHETIC METALS}, author={MATTES, BR and WANG, HL and YANG, D and al.}, year={1997}, pages={45–49} }
 @article{zhu_baldonado_peterson_al._1997, title={Powder diffraction data of SmBa4Cu3O8.5+delta}, volume={12}, number={4}, journal={POWDER DIFFRACTION}, author={ZHU, YT and BALDONADO, PS and PETERSON, EJ and al.}, year={1997}, pages={242–244} }
 @article{zhu_blumenthal_lowe_1997, title={The tensile strength of short fibre-reinforced composites}, volume={32}, number={8}, journal={JOURNAL OF MATERIALS SCIENCE}, author={ZHU, YT and BLUMENTHAL, WR and LOWE, TC}, year={1997}, pages={2037–2043} }
 @article{blumenthal_zhu_lowe_al._1996, title={Deformation state effects on the J(c) of BSCCO tapes}, volume={260}, number={1-2}, journal={PHYSICA C}, author={BLUMENTHAL, WR and ZHU, YT and LOWE, TC and al.}, year={1996}, pages={33–40} }
 @article{zhu_manthiram_1996, title={Influence of processing parameters on the formation of WC-Co nanocomposite powder using a polymer as carbon source}, volume={27}, number={5}, journal={COMPOSITES PART B-ENGINEERING}, author={ZHU, YT and MANTHIRAM, A}, year={1996}, pages={407–413} }
 @article{zhu_manthiram_1995, title={A THERMOGRAVIMETRIC STUDY OF THE INFLUENCE OF INTERNAL-STRESSES ON OXYGEN VARIATIONS IN LN(2-X)CE(X)CUO(4)}, volume={114}, number={2}, journal={JOURNAL OF SOLID STATE CHEMISTRY}, author={ZHU, YT and MANTHIRAM, A}, year={1995}, pages={491–498} }
 @article{zhu_gao_devletian_al._1995, title={DIFFERENTIAL THERMAL-ANALYSIS OF SOLID ZIRCONIUM}, volume={23}, number={6}, journal={JOURNAL OF TESTING AND EVALUATION}, author={ZHU, YT and GAO, YP and DEVLETIAN, JH and al.}, year={1995}, pages={431–435} }
 @article{zhou_savoy_lo_al._1995, title={IMPROVED CORROSION-RESISTANCE OF CATION SUBSTITUTED YBA2CU3O7-DELTA}, volume={66}, number={21}, journal={APPLIED PHYSICS LETTERS}, author={ZHOU, JP and SAVOY, SM and LO, RK and al.}, year={1995}, pages={2900–2902} }
 @article{zhu_devletian_chen_al._1995, title={ON THE NONUNIFORM DISTRIBUTIONS OF TEMPERATURE AND THERMAL-STRESS IN DTA TESTING}, volume={23}, number={1}, journal={JOURNAL OF TESTING AND EVALUATION}, author={ZHU, YT and DEVLETIAN, JH and CHEN, SJ and al.}, year={1995}, pages={63–66} }
 @article{zhu_manthiram_1994, title={A NEW ROUTE FOR THE SYNTHESIS OF TUNGSTEN CARBIDE COBALT NANOCOMPOSITES}, volume={77}, number={10}, journal={JOURNAL OF THE AMERICAN CERAMIC SOCIETY}, author={ZHU, YT and MANTHIRAM, A}, year={1994}, pages={2777–2778} }
 @article{zhu_manthiram_1994, title={A NEW ROUTE FOR THE SYNTHESIS OF TUNGSTEN-OXIDE BRONZES}, volume={110}, number={1}, journal={JOURNAL OF SOLID STATE CHEMISTRY}, author={ZHU, YT and MANTHIRAM, A}, year={1994}, pages={187–189} }
 @article{zhou_savoy_zhao_al._1994, title={CHEMICALLY TAILORED, CORROSION-RESISTANT, HIGH-T-C PHASES}, volume={116}, number={20}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={ZHOU, JP and SAVOY, SM and ZHAO, JN and al.}, year={1994}, pages={9389–9390} }
 @article{manthiram_dananjay_zhu_1994, title={NEW ROUTE TO REDUCED TRANSITION-METAL OXIDES}, volume={6}, number={10}, journal={CHEMISTRY OF MATERIALS}, author={MANTHIRAM, A and DANANJAY, A and ZHU, YT}, year={1994}, pages={1601–1602} }
 @article{manthiram_zhu_1994, title={ON THE ABSENCE OF SUPERCONDUCTIVITY IN GD2-XCEXCUO4}, volume={226}, number={1-2}, journal={PHYSICA C}, author={MANTHIRAM, A and ZHU, YT}, year={1994}, pages={165–169} }
 @article{zhu_manthiram_1994, title={ROLE OF BOND-LENGTH MISMATCH IN L2-XCEXCUO4 (L=LANTHANIDE)}, volume={49}, number={9}, journal={PHYSICAL REVIEW B}, author={ZHU, YT and MANTHIRAM, A}, year={1994}, pages={6293–6298} }
 @article{zhu_manthiram_1994, title={ROLE OF OXYGEN IN LN(2-X)CE(X)CUO4 SUPERCONDUCTORS}, volume={224}, number={3-4}, journal={PHYSICA C}, author={ZHU, YT and MANTHIRAM, A}, year={1994}, pages={256–262} }
 @article{zhu_zong_manthiram_al._1994, title={STRENGTH ANALYSIS OF RANDOM SHORT-FIBER-REINFORCED METAL-MATRIX COMPOSITE-MATERIALS}, volume={29}, number={23}, journal={JOURNAL OF MATERIALS SCIENCE}, author={ZHU, YT and ZONG, G and MANTHIRAM, A and al.}, year={1994}, pages={6281–6286} }
 @article{manthiram_zhu_1993, title={CHEMISTRY OF ELECTRON-DOPED LN2-XCEXCUO4 SUPERCONDUCTORS}, volume={22}, number={10}, journal={JOURNAL OF ELECTRONIC MATERIALS}, author={MANTHIRAM, A and ZHU, YT}, year={1993}, pages={1195–1198} }
 @article{zhu_zong_1993, title={ON THE APPLICATION OF THE STATISTICAL STRENGTH MODEL OF FIBER-REINFORCED COMPOSITES}, volume={27}, number={9}, journal={JOURNAL OF COMPOSITE MATERIALS}, author={ZHU, YT and ZONG, GS}, year={1993}, pages={944–959} }
 @article{zhu_devletian_1992, title={THERMAL-STRESS AND STRAIN EFFECTS ON PHASE-TRANSITION TEMPERATURES IN DIFFERENTIAL THERMAL-ANALYSIS TESTING}, volume={23}, number={2}, journal={METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={ZHU, YT and DEVLETIAN, JH}, year={1992}, pages={451–455} }
 @article{zhu_devletian_1991, title={DETERMINATION OF EQUILIBRIUM SOLID-PHASE TRANSITION-TEMPERATURE USING DTA}, volume={22}, number={9}, journal={METALLURGICAL TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE}, author={ZHU, YT and DEVLETIAN, JH}, year={1991}, pages={1993–1998} }
 @article{zhu_devletian_1991, title={PRECISE DETERMINATION OF ISOMORPHOUS AND EUTECTOID TRANSFORMATION TEMPERATURES IN BINARY AND TERNARY ZR ALLOYS}, volume={26}, number={22}, journal={JOURNAL OF MATERIALS SCIENCE}, author={ZHU, YT and DEVLETIAN, JH}, year={1991}, pages={6218–6222} }
 @article{zhu_devletian_1991, title={PRECISE DTA TESTING OF HIGHLY REACTIVE ALLOYS}, volume={140}, number={4}, journal={ADVANCED MATERIALS & PROCESSES}, author={ZHU, YT and DEVLETIAN, JH}, year={1991}, pages={51–53} }
 @article{zhu_zhou_he_al._1989, title={A STATISTICAL-THEORY OF COMPOSITE-MATERIALS STRENGTH}, volume={23}, number={3}, journal={JOURNAL OF COMPOSITE MATERIALS}, author={ZHU, YT and ZHOU, BL and HE, GH and al.}, year={1989}, pages={280–287} }