School of Materials Science and Engineering, Beihang University, Beijing 100191, China.
Phys Chem Chem Phys. 2018 Jul 4;20(26):17727-17738. doi: 10.1039/c8cp03241f.
Molecular dynamics simulations are performed to investigate the orientation and temperature dependence of tensile response in single crystal W. It is found that W single crystal exhibits distinct temperature-dependent deformation behaviors along different orientations. With increasing temperature, the yield strain in the [001] orientation increases, while those in [110] and [111] orientations first increase and then decrease. The tensile deformations along orientations close to [001] are found to be dominated by twinning; the nucleation and growth of twins are accomplished through the nucleation and glide of ⅙111 partial dislocations on {112} planes. In contrast, the deformations along orientations close to [110] and [111] are found to be dominated by the slip of ½111 full dislocations, which move in a stay-and-go fashion. Moreover, intermediate deformation behaviors, which may become unstable at high temperatures, are observed for some intervening orientations. The distinct deformation behaviors of W along different orientations are rationalized based on the twinning-antitwinning asymmetry of ⅙111 partial dislocations on {112} planes.
采用分子动力学模拟方法研究了单晶 W 在拉伸过程中的取向和温度依赖性。研究发现，W 单晶在不同取向下表现出明显的温度相关变形行为。随着温度的升高，[001]取向的屈服应变增加，而[110]和[111]取向的屈服应变先增加后减小。发现在接近[001]取向的拉伸变形由孪晶主导；孪晶的形核和生长是通过{112}面上的 ⅙111 部分位错的形核和滑移来完成的。相比之下，接近[110]和[111]取向的变形由½111 全位错的滑移主导，这些位错以走走停停的方式移动。此外，对于一些中间取向，还观察到了中间变形行为，这些行为在高温下可能变得不稳定。基于{112}面上的 ⅙111 部分位错的孪晶-反孪晶不对称性，对 W 在不同取向下的不同变形行为进行了合理化解释。
