We use molecular dynamics to show that plastic slip is a crucial component of the transformation mechanism of a square-to-triangular structural transition. The latter is a stylized analog of many other reconstructive phase transitions. To justify our conclusions we use a novel atomistically-informed mesoscopic representation of the field of lattice distortions in molecular dynamics simulations. Our approach reveals a hidden alternating slip distribution behind the seemingly homogeneous product phase which points to the fact that lattice invariant shears play a central role in this class of phase transformations. While the underlying pattern of anti-parallel displacements may be also interpreted as microscopic shuffling, its precise crystallographic nature strongly suggests the plasticity-centered interpretation.
A Surface Stacking Fault Energy Approach to Predicting Defect Nucleation in Surface-Dominated Nanostructures
我们提出了一个表面堆垛层错（SSF）能量的方法来预测缺陷成核从表面占主导地位的纳米结构，如FCC金属纳米线的表面。该方法导致一个标准，预测初始屈服机制，通过滑移或孪晶取决于是否不稳定的孪晶能量或不稳定的滑移能量是从所得SSF能量曲线确定的较小。该方法通过SSF能量计算和低温经典分子动力学模拟之间的比较与不同的轴向和横向表面取向，和横截面的几何形状的铜纳米线进行验证。我们专注于几何截面的影响，通过研究从滑移到孪晶的过渡先前预测的移动从正方形到矩形截面的$\ <100\ > /\{100\}$纳米线，也为移动从菱形到截断菱形截面几何形状的$\ <110\ >$纳米线。\hsp{We also provide the important demonstration that the criteria is able to predict the correct deformation mechanism when full dislocation slip is considered concurrently with partial dislocation slip and twinning. This is done in the context of rhombic aluminum nanowires which do not show a tensile reorientati…
