模型二元有序合金固液界面结构的分子动力学研究

采用分子动力学方法,研究了模型二元有序合金体系的平衡界面结构和界面处原子的扩散行为.计算结果表明,该二元有序合金的固液界面属于光滑界面.由于固体中同时存在结构和化学有序,从而导致界面处的原子结构与单质以及异质固液界面的结构明显不同.在界面法向方向上,粒子数密度呈复杂的波动行为,并延伸到液体中约30 (A).对界面层的二维结构分析表明,固液转变层部分原子形成了二维固体团簇.从固体到液体,扩散系数从零逐渐增加到一个饱和值.在界面处附近,平行于界面方向的扩散系数明显比垂直于界面方向的大.

Atomistic characterization of a modeled binary ordered alloy solid-liquid interface

Using molecular dynamics simulations, we investigate the structure and transport properties of solid-liquid interface in a model ordered alloy. Our results show that the studied interface is a smooth interface. Due to the coexistence of structural order and chemical order, the structure of this interface is remarkably different from heterogeneous or pure element solid-liquid interface. The number density oscillates in a complicated way along the interface normal direction, and this oscillation goes into liquid around 30 Å. The two-dimensional structural analysis shows that the atoms form two-dimensional ordered clusters in the transition layer. The diffusion constant gradually increases from zero to a saturation value in the liquid side far from the interface. In the vicinity of the interface, the diffusion constant parallel to the interface direction is large than that along interface normal.