论文标题
FCC金属中双胞胎位错的核心结构和晶格抗性
Core-structure and lattice resistance of twinning dislocations in fcc metals
论文作者
论文摘要
具有FCC结构的金属可能在特定条件下表现出变形，这是其变形行为的一个有趣但难以捉摸的方面。人们众所周知，这种现象是通过孪生部分脱位的活动发生的。但是，缺乏对其基本特性的全面理解阻碍了FCC金属中详细的晶体可塑性模型的发展。在这里，我们通过原子知情的数值建模来探索双部分分支的核心结构和格子摩擦。为此，我们选择了四个FCC晶体，其堆叠断层能量差异很大。使用半污染的变异PEIERLS NABARRO模型，我们计算边缘和螺钉孪晶脱位的核心宽度和PEIERLS应力。除了双胞胎成核的常规层层模型外，最近提出的替代剪切模型也已被检查。在后一种情况下，已经观察到负稳定的断层能量，足够大以克服PEIERLS屏障。这项研究还强调了纳入表面校正的意义，而表面校正的缺失导致对双脱位的内在晶格抗性高估。
Metals with fcc structure may exhibit deformation twinning under specific conditions, which is an interesting but somewhat elusive aspect of their deformation behavior. It is well acknowledged that the phenomenon occurs through the activities of twinning partial dislocations. However, the lack of a comprehensive understanding of their fundamental properties obstructs the development of detailed multiscale models of crystal plasticity in the fcc metals. Here we explore the core-structures and lattice friction of twinning partials through atomistically informed numerical modeling. To this end, we choose four fcc crystals with widely differing stacking fault energies. Using the semi-discrete variational Peierls Nabarro model, we compute the core-widths and Peierls stresses of edge and screw twinning dislocations. Apart from the conventional layer-by-layer model of twin nucleation, the recently proposed alternate-shear model has also been examined. In the latter case, a negative stable fault energy has been observed, which is large enough to overcome the Peierls barrier. This study also highlights the significance of incorporating the surface correction, the absence of which leads to an overestimation of the intrinsic lattice resistance of the twinning dislocations.
