论文标题
FCC金属中孪晶位错环的成核
Nucleation of twinning dislocation loops in fcc metals
论文作者
论文摘要
变形孪生仅在固有物质特性，微结构和加载条件的特定条件下发生在FCC金属中，在其变形机制图中占据了必不可少的位置。尽管如此，很少进行专门的研究来探索介导该过程的双胞胎脱位的基本特性。在这里，我们采用了原子计算和连续建模的组合来研究具有FCC晶体结构的金属中的双胞胎脱位环的成核。除了双核的常规层层模型外，还研究了新提出的替代剪切机制，并确定了双环成核的能屏障和剪切应力。我们发现后一种机制中的成核应力比前者小。该研究还强调了临界环大小和分数汉堡矢量的不均匀变化，并具有施加的剪切载荷。
Deformation twinning, which occurs in fcc metals only under particular conditions of intrinsic material properties, microstructure, and loading conditions, occupies an indispensable place in their deformation mechanism maps. Nonetheless, dedicated studies have seldom been carried out to explore the fundamental properties of twinning dislocations mediating this process. Here we employ a combination of atomistic computations and continuum modeling to investigate the nucleation of twinning dislocation loops in metals with fcc crystal structure. Besides the conventional layer-by-layer model of twin nucleation, the newly proposed alternate-shear mechanism has been investigated, and the energy barrier and shear stress for twinning loop nucleation have been determined. We find the nucleation stress in the latter mechanism to be smaller than that in the former. The study also highlights the non-uniform variations of the critical loop size and fractional Burgers vector with the applied shear load.
