@article{he_cheng_zhu_park_2023, title={Surface Adatom Diffusion-Assisted Dislocation Nucleation in Metal Nanowires}, volume={23}, ISSN={["1530-6992"]}, DOI={10.1021/acs.nanolett.3c01660}, abstractNote={We employ a hybrid diffusion- and nucleation-based kinetic Monte Carlo model to elucidate the significant impact of adatom diffusion on incipient surface dislocation nucleation in metal nanowires. We reveal a stress-regulated diffusion mechanism that promotes preferential accumulation of diffusing adatoms near nucleation sites, which explains the experimental observations of strong temperature but weak strain-rate dependence as well as temperature-dependent scatter of the nucleation strength. Furthermore, the model demonstrates that a decreasing rate of adatom diffusion with an increasing strain rate will lead to stress-controlled nucleation being the dominant nucleation mechanism at higher strain rates. Overall, our model offers new mechanistic insights into how surface adatom diffusion directly impacts the incipient defect nucleation process and resulting mechanical properties of metal nanowires.}, number={12}, journal={NANO LETTERS}, author={He, Lijie and Cheng, Guangming and Zhu, Yong and Park, Harold S.}, year={2023}, month={Jun}, pages={5779–5784} }
 @article{yin_cheng_zhu_gao_2020, title={Competition between shear localization and tensile detwinning in twinned nanowires}, volume={4}, ISSN={["2475-9953"]}, DOI={10.1103/PhysRevMaterials.4.023603}, abstractNote={Recently, a transition of deformation mechanism from localized dislocation slip to delocalized plasticity via an anomalous tensile detwinning mechanism has been discovered in bitwinned metallic nanowires (NWs) with a single twin boundary (TB) running parallel to the NW length. However, experiments showed that the anomalous tensile detwinning in most of bitwinned NWs does not propagate through the whole NW, which limits the NWs failure strain when compared to the twinning-induced superplasticity in single-crystalline NWs. An elusive but fundamentally important question is that what factors might affect the propagation of tensile detwinning in such bitwinned NWs. In addition, can this tensile detwinning mechanism be applied to other types of twinned NWs? Here, based on in situ transmission electron microscopy testing and molecular dynamics simulations, a competition between shear localization and tensile detwinning is identified. By dividing the tensile detwinning mechanism into two steps and investigating each step separately, it is found that the quality of a single-crystalline embryo formed during step one determines the succeeding detwinning propagation (step two) and the final plastic strain. Furthermore, this anomalous tensile detwinning mechanism is extended to other metallic NWs with multiple TBs running parallel to the length direction, such as asymmetric pentatwinned NWs and NWs with multiple parallel TBs. This work highlights the important role of detwinning in large plasticity in metallic NWs with different twin structures.}, number={2}, journal={PHYSICAL REVIEW MATERIALS}, author={Yin, Sheng and Cheng, Guangming and Zhu, Yong and Gao, Huajian}, year={2020}, month={Feb} }
 @article{cheng_yin_li_chang_richter_gao_zhu_2020, title={In-situ TEM study of dislocation interaction with twin boundary and retraction in twinned metallic nanowires}, volume={196}, ISSN={["1873-2453"]}, DOI={10.1016/j.actamat.2020.06.055}, abstractNote={Metallic nanowires (NWs) with twin boundaries (TBs) running parallel to the NW length direction exhibit unusual plastic strain recovery owing to the interaction of dislocations with TBs. Here, based on in-situ transmission electron microscopy nanomechanical testing and molecular dynamics simulations, we report observation and quantification of dislocation nucleation, interaction with TBs, and retraction in bi-twinned Ag NWs with a single TB along the NW length direction. Our results show that leading partial dislocations nucleated from the free surface can be hindered by the TB, and upon unloading all or part of the leading partials can retract due to the repulsive force from the TB, leading to full or partial plastic strain recovery (Bauschinger effect), respectively. The bi-twinned Ag NWs can undergo stress relaxation, even at a stress below the yield strength, where the plastic strain also recovers upon unloading. The relaxation and recovery behaviors are compared to those of penta-twinned Ag NWs. Our results illustrate that the internal TBs in NWs can interact with surface-nucleated dislocations, leading to time-dependent plastic strain recovery and Bauschinger effect.}, journal={ACTA MATERIALIA}, author={Cheng, Guangming and Yin, Sheng and Li, Chengjun and Chang, Tzu-Hsuan and Richter, Gunther and Gao, Huajian and Zhu, Yong}, year={2020}, month={Sep}, pages={304–312} }
 @article{sha_xiao_chen_cheng_yu_yin_zhou_2019, title={Atomic structure of gamma '' phase in Mg-Gd-Y-Ag alloy induced by Ag addition}, volume={99}, ISSN={["1478-6443"]}, DOI={10.1080/14786435.2019.1606466}, abstractNote={ABSTRACT Mg–Gd based alloys are typical high strength magnesium alloys owing to their outstanding age hardening behavior. The mechanical strength of aged Mg–Gd alloys is enhanced by high density prismatic-shaped precipitates in Mg matrix. Moreover, the addition of Ag has been found to enhance the strength of Mg–Gd based alloys further by forming a plate-shaped precipitate, named as γ″, on basal planes of Mg. However, the structure of this precipitate is not well understood due to the complex alloying system. In this work, the atomic structure of γ″ phase is investigated using atomic-resolution high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Based on the accurate atomic structure from three independent directions, e.g. in [0001]Mg, [110]Mg and [010]Mg zone axes, the unit cell of γ″ is well established. The γ″ phase has a hexagonal structure, and its lattice parameters are a = 0.55 nm and c = 0.42 nm. The orientation relationship between γ″ phase and Mg matrix is (0001)γ″//(0001)Mg and <110>γ″//<010>Mg.}, number={16}, journal={PHILOSOPHICAL MAGAZINE}, author={Sha, Xuechao and Xiao, Lirong and Chen, Xuefei and Cheng, Guangming and Yu, Yandong and Yin, Dongdi and Zhou, Hao}, year={2019}, month={Aug}, pages={1957–1969} }
 @article{yin_cheng_chang_richter_zhu_gao_2019, title={Hydrogen embrittlement in metallic nanowires}, volume={10}, ISSN={["2041-1723"]}, DOI={10.1038/s41467-019-10035-0}, abstractNote={Abstract}, journal={NATURE COMMUNICATIONS}, author={Yin, Sheng and Cheng, Guangming and Chang, Tzu-Hsuan and Richter, Gunther and Zhu, Yong and Gao, Huajian}, year={2019}, month={May} }
 @article{cheng_zhang_chang_liu_chen_lu_zhu_zhu_2019, title={In Situ Nano-thermomechanical Experiment Reveals Brittle to Ductile Transition in Silicon Nanowires}, volume={19}, ISSN={["1530-6992"]}, DOI={10.1021/acs.nanolett.9b01789}, abstractNote={Silicon (Si) nanostructures are widely used in microelectronics and nanotechnology. Brittle to ductile transition in nanoscale Si is of great scientific and technological interest, but this phenomenon and its underlying mechanism remain elusive. By conducting in situ temperature-controlled nanomechanical testing inside a transmission electron microscope (TEM), here we show that the crystalline Si nanowires under tension are brittle at room temperature, but exhibit ductile behavior with dislocation-mediated plasticity at elevated temperatures. We find that reducing the nanowire diameter promotes the dislocation-mediated responses, as shown by 78 Si nanowires tested between room temperature and 600 K. In situ high resolution TEM imaging and atomistic reaction pathway modeling reveal that the unconventional ½〈110〉{001} dislocations become highly active with increasing temperature and thus play a critical role in the formation of deformation bands, leading to transition from brittle fracture to dislocation-mediated failure in Si nanowires at elevated temperatures. This study provides quantitative characterization and mechanistic insight for the brittle to ductile transition in Si nanostructures.}, number={8}, journal={NANO LETTERS}, author={Cheng, Guangming and Zhang, Yin and Chang, Tzu-Hsuan and Liu, Qunfeng and Chen, Lin and Lu, Wei D. and Zhu, Ting and Zhu, Yong}, year={2019}, month={Aug}, pages={5327–5334} }
 @article{yin_cheng_richter_gao_zhu_2019, title={Transition of Deformation Mechanisms in Single-Crystalline Metallic Nanowires}, volume={13}, ISSN={["1936-086X"]}, DOI={10.1021/acsnano.9b03311}, abstractNote={Twinning and dislocation slip are two competitive deformation mechanisms in face-centered cubic (FCC) metals. For FCC metallic nanowires (NWs), the competition between these mechanisms was found to depend on loading direction and material properties. Here, using in situ transmission electron microscopy tensile tests and molecular dynamics simulations, we report an additional factor, cross-sectional shape, that can affect the competition between the deformation mechanisms in single crystalline FCC metallic NWs. For a truncated rhombic cross-section, the extent of truncation determines the competition. Specifically, a transition from twinning to localized dislocation slip occurs with increasing extent of truncation. Theoretical and simulation results indicate that the energy barriers for twinning and dislocation slip depend on the cross-sectional shape of the NW. The energy barrier for twinning is proportional to the change of surface energy associated with the twinning. Thus, the transition of deformation modes can be attributed to the change of surface energy as a function of the cross-sectional shape.}, number={8}, journal={ACS NANO}, author={Yin, Sheng and Cheng, Guangming and Richter, Gunther and Gao, Huajian and Zhu, Yong}, year={2019}, month={Aug}, pages={9082–9090} }
 @article{cheng_yin_chang_richter_gao_zhu_2017, title={Anomalous Tensile Detwinning in Twinned Nanowires}, volume={19}, ISSN={["1079-7114"]}, DOI={10.1103/physrevlett.119.256101}, abstractNote={In spite of numerous studies on mechanical behaviors of nanowires (NWs) focusing on the surface effect, there is still a general lack of understanding on how the internal microstructure of NWs influences their deformation mechanisms. Here, using quantitative in situ transmission electron microscopy based nanomechanical testing and molecular dynamics simulations, we report a transition of the deformation mechanism from localized dislocation slip to delocalized plasticity via an anomalous tensile detwinning mechanism in bitwinned metallic NWs with a single twin boundary (TB) running parallel to the NW length. The anomalous tensile detwinning starts with the detwinning of a segment of the preexisting TB under no resolved shear stress, followed by the propagation of a pair of newly formed TB and grain boundary leading to a large plastic deformation. An energy-based criterion is proposed to describe this transition of the deformation mechanism, which depends on the volume ratio between the two twin variants and the cross-sectional aspect ratio.}, number={25}, journal={PHYSICAL REVIEW LETTERS}, author={Cheng, Guangming and Yin, Sheng and Chang, Tzu-Hsuan and Richter, Gunther and Gao, Huajian and Zhu, Yong}, year={2017}, month={Dec} }
 @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{cheng_yao_sang_hao_zhang_yap_zhu_2016, title={Evolution of Irradiation-Induced Vacancy Defects in Boron Nitride Nanotubes}, volume={12}, ISSN={["1613-6829"]}, DOI={10.1002/smll.201502440}, abstractNote={Irradiation‐induced vacancy defects in multiwalled (MW) boron nitride nanotubes (BNNTs) are investigated via in situ high‐resolution transmission electron microscope operated at 80 kV, with a homogeneous distribution of electron beam intensity. During the irradiation triangle‐shaped vacancy defects are gradually generated in MW BNNTs under a mediate electron current density (30 A cm−2), by knocking the B atoms out. The vacancy defects grow along a well‐defined direction within a wall at the early stage as a result of the curvature induced lattice strain, and then develop wall by wall. The orientation or the growth direction of the vacancy defects can be used to identify the chirality of an individual wall. With increasing electron current density, the shape of the irradiation‐induced vacancy defects changes from regular triangle to irregular polygon.}, number={6}, journal={SMALL}, author={Cheng, Guangming and Yao, Shanshan and Sang, Xiahan and Hao, Boyi and Zhang, Dongyan and Yap, Yoke Khin and Zhu, Yong}, year={2016}, month={Feb}, pages={818–824} }
 @article{chang_cheng_li_zhu_2016, title={On the size-dependent elasticity of penta-twinned silver nanowires}, volume={8}, ISSN={["2352-4316"]}, DOI={10.1016/j.eml.2016.03.007}, abstractNote={Penta-twinned metallic NWs have recently received much attention due to their excellent mechanical properties. However, their elasticity size effect remains not well understood due to the large discrepancy in the reported experimental and simulation results. This paper reports an experimental effort to address the discrepancy about the size-dependent Young’s modulus of penta-twinned Ag NWs. Two independent experiments on the same NW, in-situ resonance test and tensile test in a scanning electron microscope, were used to measure the Young’s moduli. The cross-sectional shape of the Ag NWs was found to transit from pentagon to circle with decreasing NW diameter, which can modify the Young’s modulus as much as 8% (for resonance test) and 19% (for tensile test) for the tested diameter range. This work confirmed that the Young’s modulus of penta-twinned Ag NWs increases with decreasing NW diameter.}, journal={EXTREME MECHANICS LETTERS}, author={Chang, Tzu-Hsuan and Cheng, Guangming and Li, Chengjun and Zhu, Yong}, year={2016}, month={Sep}, pages={177–183} }
 @article{cui_poblete_cheng_yao_jiang_zhu_2015, title={Design and operation of silver nanowire based flexible and stretchable touch sensors}, volume={30}, ISSN={["2044-5326"]}, DOI={10.1557/jmr.2014.347}, abstractNote={Abstract}, number={1}, journal={JOURNAL OF MATERIALS RESEARCH}, author={Cui, Zheng and Poblete, Felipe R. and Cheng, Guangming and Yao, Shanshan and Jiang, Xiaoning and Zhu, Yong}, year={2015}, month={Jan}, pages={79–85} }
 @article{cheng_miao_qin_li_xu_haftbaradaran_dickey_gao_zhu_2015, title={Large anelasticity and associated energy dissipation in single-crystalline nanowires}, volume={10}, ISSN={1748-3387 1748-3395}, url={http://dx.doi.org/10.1038/NNANO.2015.135}, DOI={10.1038/nnano.2015.135}, abstractNote={Anelastic materials exhibit gradual full recovery of deformation once a load is removed, leading to dissipation of internal mechanical energy. As a consequence, anelastic materials are being investigated for mechanical damping applications. At the macroscopic scale, however, anelasticity is usually very small or negligible, especially in single-crystalline materials. Here, we show that single-crystalline ZnO and p-doped Si nanowires can exhibit anelastic behaviour that is up to four orders of magnitude larger than the largest anelasticity observed in bulk materials, with a timescale on the order of minutes. In situ scanning electron microscope tests of individual nanowires showed that, on removal of the bending load and instantaneous recovery of the elastic strain, a substantial portion of the total strain gradually recovers with time. We attribute this large anelasticity to stress-gradient-induced migration of point defects, as supported by electron energy loss spectroscopy measurements and also by the fact that no anelastic behaviour could be observed under tension. We model this behaviour through a theoretical framework by point defect diffusion under a high strain gradient and short diffusion distance, expanding the classic Gorsky theory. Finally, we show that ZnO single-crystalline nanowires exhibit a high damping merit index, suggesting that crystalline nanowires with point defects are promising materials for energy damping applications.}, number={8}, journal={Nature Nanotechnology}, publisher={Springer Science and Business Media LLC}, author={Cheng, Guangming and Miao, Chunyang and Qin, Qingquan and Li, Jing and Xu, Feng and Haftbaradaran, Hamed and Dickey, Elizabeth C. and Gao, Huajian and Zhu, Yong}, year={2015}, month={Jul}, pages={687–691} }
 @article{qin_yin_cheng_li_chang_richter_zhu_gao_2015, title={Recoverable plasticity in penta-twinned metallic nanowires governed by dislocation nucleation and retraction}, volume={6}, ISSN={["2041-1723"]}, DOI={10.1038/ncomms6983}, abstractNote={Abstract}, journal={NATURE COMMUNICATIONS}, author={Qin, Qingquan and Yin, Sheng and Cheng, Guangming and Li, Xiaoyan and Chang, Tzu-Hsuan and Richter, Gunther and Zhu, Yong and Gao, Huajian}, year={2015}, month={Jan} }
 @article{narayanan_cheng_zeng_zhu_zhu_2015, title={Strain Hardening and Size Effect in Five-fold Twinned Ag Nanowires}, volume={15}, ISSN={["1530-6992"]}, DOI={10.1021/acs.nanolett.5b01015}, abstractNote={Metallic nanowires usually exhibit ultrahigh strength but low tensile ductility owing to their limited strain hardening capability. Here we study the unique strain hardening behavior of the five-fold twinned Ag nanowires by nanomechanical testing and atomistic modeling. In situ tensile tests within a scanning electron microscope revealed strong strain hardening behavior of the five-fold twinned Ag nanowires. Molecular dynamics simulations showed that such strain hardening was critically controlled by twin boundaries and pre-existing defects. Strain hardening was size dependent; thinner nanowires achieved more hardening and higher ductility. The size-dependent strain hardening was found to be caused by the obstruction of surface-nucleated dislocations by twin boundaries. Our work provides mechanistic insights into enhancing the tensile ductility of metallic nanostructures by engineering the internal interfaces and defects.}, number={6}, journal={NANO LETTERS}, author={Narayanan, Sankar and Cheng, Guangming and Zeng, Zhi and Zhu, Yong and Zhu, Ting}, year={2015}, month={Jun}, pages={4037–4044} }
 @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{cheng_chang_qin_huang_zhu_2014, title={Mechanical Properties of Silicon Carbide Nanowires: Effect of Size-Dependent Defect Density}, volume={14}, ISSN={["1530-6992"]}, DOI={10.1021/nl404058r}, abstractNote={This paper reports quantitative mechanical characterization of silicon carbide (SiC) nanowires (NWs) via in situ tensile tests inside scanning electron microscopy using a microelectromechanical system. The NWs are synthesized using the vapor-liquid-solid process with growth direction of ⟨111⟩. They consist of three types of structures, pure face-centered cubic (3C) structure, 3C structure with an inclined stacking fault (SF), and highly defective structure, in a periodic fashion along the NW length. The SiC NWs are found to deform linear elastically until brittle fracture. Their fracture origin is identified in the 3C structures with inclined SFs, rather than the highly defective structures. The fracture strength increases as the NW diameter decreases from 45 to 17 nm, approaching the theoretical strength of 3C SiC. The size effect on fracture strength of SiC NWs is attributed to the size-dependent defect density rather than the surface effect that is dominant for single crystalline NWs.}, number={2}, journal={NANO LETTERS}, author={Cheng, Guangming and Chang, Tzu-Hsuan and Qin, Qingquan and Huang, Hanchen and Zhu, Yong}, year={2014}, month={Feb}, pages={754–758} }
 @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{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{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{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{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} }