Niu Liang-Liang, Zhang Ying, Shu Xiaolin, Gao Fei, Jin Shuo, Zhou Hong-Bo, Lu Guang-Hong
Department of Physics, Beihang University, Beijing 100191, China.
Department of Nuclear Engineering and Radiological Science, University of Michigan, Ann Arbor, MI 48109, USA.
Sci Rep. 2016 Mar 24;6:23602. doi: 10.1038/srep23602.
Shear-coupled grain boundary (GB) migration can be an efficacious mechanism to accommodate plastic deformation when the grain size of polycrystalline materials goes small. Nevertheless, how this kind of GB motion comes into play at the atomic level has not been fully revealed. Here, we have investigated the shear-coupled migration (SCM) of typical [100] group symmetrical tilt GBs in bcc W using atomistic simulations. Depending on GB character, the SCM is found to proceed via dislocation slipping in the 〈100〉 or 〈110〉 mode with striking shear strength difference between them. We demonstrate that there exists an unusual atomic shuffling along the tilt axis, which greatly assists SCM to operate in the easier 〈110〉 mode instead of the 〈100〉 one. The present results highlight the significant role of GB character in the atomistic SCM process and contribute to the future design and fabrication of high-performance materials in GB engineering.
当多晶材料的晶粒尺寸变小时，剪切耦合晶界迁移可能是一种有效的机制来适应塑性变形。然而，这种晶界运动在原子层面是如何发生作用的尚未完全揭示。在此，我们使用原子模拟研究了体心立方钨中典型的[100]组对称倾斜晶界的剪切耦合迁移（SCM）。根据晶界特性，发现SCM通过〈100〉或〈110〉模式的位错滑移进行，它们之间的剪切强度差异显著。我们证明，沿倾斜轴存在异常的原子重排，这极大地有助于SCM以更容易的〈110〉模式而非〈100〉模式运行。目前的结果突出了晶界特性在原子SCM过程中的重要作用，并有助于未来晶界工程中高性能材料的设计和制造。
