@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{min_chen_chen_sun_lee_li_zhu_brendan t. o'connor_parsons_chang_2018, title={Conformal Physical Vapor Deposition Assisted by Atomic Layer Deposition and Its Application for Stretchable Conductors}, volume={5}, ISSN={["2196-7350"]}, DOI={10.1002/admi.201801379}, abstractNote={Abstract}, number={22}, journal={ADVANCED MATERIALS INTERFACES}, author={Min, Joong-Hee and Chen, Yi-An and Chen, I-Te and Sun, Tianlei and Lee, Dennis T. and Li, Chengjun and Zhu, Yong and Brendan T. O'Connor and Parsons, Gregory N. and Chang, Chih-Hao}, year={2018}, month={Nov} }
 @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} }