In-situ TEM study of dislocation interaction with twin boundary and retraction in twinned metallic nanowires
In-situ TEM study of dislocation interaction with twin boundary and retraction in twinned metallic nanowires
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DOI：
10.1016/j.actamat.2020.06.055
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发表时间：
2020-09-01
期刊：
影响因子：
9.4
通讯作者：
Zhu, Yong
中科院分区：
文献类型：
--
作者：
Cheng, Guangming;Yin, Sheng;Zhu, Yong
具有平行于纳米线长度方向的孪晶界的金属纳米线由于位错与孪晶界的相互作用而表现出不寻常的塑性应变恢复。在这里，基于原位透射电子显微镜纳米力学测试和分子动力学模拟，我们报告观察和量化的位错成核，与TB的相互作用，并在双孪晶银纳米线与一个单一的TB沿着NW长度方向的收缩。我们的研究结果表明，领先的部分位错从自由表面形核可以阻碍TB，卸载后，所有或部分的领先的部分可以缩回由于从TB的排斥力，导致全部或部分塑性应变恢复（Bauschinger效应），分别。双孪晶银纳米线可以经历应力松弛，甚至在低于屈服强度的应力下，其中塑性应变也在卸载时恢复。的弛豫和恢复行为进行了比较的五孪晶银纳米线。结果表明，纳米线中的内部TB可以与表面形核位错相互作用，导致与时间相关的塑性应变恢复和Bauschinger效应。(C)2020 Acta Materialia Inc.由爱思唯尔有限公司出版。保留所有权利。
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. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.