Wang Zhang-Jie, Li Qing-Jie, Li Yao, Huang Long-Chao, Lu Lei, Dao Ming, Li Ju, Ma Evan, Suresh Subra, Shan Zhi-Wei
Center for Advancing Materials Performance from the Nanoscale and Hysitron Applied Research Center in China, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an, 710049, China.
Department of Materials Science and Engineering, Johns Hopkins University, Baltimore, MD, 21218, USA.
Nat Commun. 2017 Oct 24;8(1):1108. doi: 10.1038/s41467-017-01234-8.
Coherent twin boundaries (CTBs) are internal interfaces that can play a key role in markedly enhancing the strength of metallic materials while preserving their ductility. They are known to accommodate plastic deformation primarily through their migration, while experimental evidence documenting large-scale sliding of CTBs to facilitate deformation has thus far not been reported. We show here that CTB sliding is possible whenever the loading orientation enables the Schmid factors of leading and trailing partial dislocations to be comparable to each other. This theoretical prediction is confirmed by real-time transmission electron microscope experimental observations during uniaxial deformation of copper pillars with different orientations and is further validated at the atomic scale by recourse to molecular dynamics simulations. Our findings provide mechanistic insights into the evolution of plasticity in heavily twinned face-centered cubic metals, with the potential for optimizing mechanical properties with nanoscale CTBs in material design.
相干孪晶界（CTBs）是内部界面，在显著提高金属材料强度的同时保持其延展性方面可发挥关键作用。已知它们主要通过迁移来适应塑性变形，然而，迄今为止尚未有记录表明CTBs会大规模滑动以促进变形的实验证据。我们在此表明，只要加载方向能使领先和落后部分位错的施密德因子相互可比，CTB滑动就是可能的。这一理论预测通过不同取向铜柱单轴变形过程中的实时透射电子显微镜实验观察得到证实，并通过分子动力学模拟在原子尺度上进一步得到验证。我们的研究结果为严重孪晶的面心立方金属中塑性演化提供了机理见解，在材料设计中利用纳米级CTBs优化力学性能具有潜力。
