Origins of strengthening and failure in twinned Au nanowires: Insights from in−situ experiments and atomistic simulations
Origins of strengthening and failure in twinned Au nanowires: Insights from in−situ experiments and atomistic simulations
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DOI：
10.1016/j.actamat.2020.01.038
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发表时间：
2020-01
期刊：
影响因子：
9.4
通讯作者：
Zhuocheng Xie;Jungho Shin;Jakob Renner;A. Prakash;D. Gianola;E. Bitzek
中科院分区：
文献类型：
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作者：
Zhuocheng Xie;Jungho Shin;Jakob Renner;A. Prakash;D. Gianola;E. Bitzek
摘要利用i n− si t u实验和分子动力学模拟研究了具有多个纵向共格孪晶界的110取向孪晶Au纳米线在拉伸下的变形行为。孪晶纳米线的屈服强度高于直径相近的单晶纳米线。使用电子显微镜和MD模拟的尸检观察表明，CTBs的存在下，从孪晶介导的变形在单晶纳米线的强烈本地化变形的管理机制过渡。MD模拟表明，在CTB与自由表面的沉积的部分位错的交叉点起着重要的作用，在传输的位错，导致形成完整的位错，而不是部分位错和孪晶的情况下，单晶纳米线。此外，导致局部变形的完全位错滑移的重复激活取决于表面小平面与激活的Burgers矢量的相对取向。这项工作的结果增强了对孪生纳米物体变形机制的理解，并提出了纳米尺度机械系统的设计策略。
Abstract The deformation behavior of⟨ 110⟩-oriented twinned Au nanowires (NWs) with multiple longitudinal coherent twin boundaries (CTBs) under tension is studied using i n− s i t u experiments and molecular dynamics (MD) simulations. The twinned NWs show higher yield strength than the single-crystalline NWs with similar diameter. Postmortem observations using electron microscopy and MD simulations show that the presence of CTBs transitions the governing mechanism from twinning-mediated deformation in single-crystalline NWs to strongly localized deformation. MD simulations reveal that the intersection of deposited partial dislocations at the CTB with the free surfaces plays an important role in the transmission of the dislocation, leading to the formation of full dislocations instead of partial dislocations and twinning in the case of single-crystalline NWs. The repeated activation of full dislocation slip leading to localized deformation is furthermore dependent on the relative orientation of surface facets to the activated Burgers vectors. The results of this work enhance the understanding of deformation mechanisms of twinned nano-objects and suggest design strategies for mechanical systems at the nanoscale.