液态合金NiAl凝固过程中微观结构转变的分子动力学模拟

采用分子动力学模拟方法对液态NiAl凝固过程进行了研究 ,考察了不同冷却速度下液态NiAl结构变化特点 ,原子间相互作用势采用F S多体势 ,结构分析采用键取向序和对分析技术 .计算结果表明 ,冷却速度对液态NiAl结构转变有重要影响 ,在不同的冷却速度下 ,NiAl凝固过程出现了明显不同 ,冷速为 4× 10 13 和4× 10 12 K/s时 ,NiAl快速凝固为无序的非晶体结构 ;而在较慢的 8× 10 11K/s冷速下 ,NiAl凝固为晶态结构 .给出了不同冷却速度下液态NiAl结构转变的微观信息 .

Molecular Dynamics Simulations of Solidification of Liquid NiAl

By means of the molecular dynamics simulation technique, the rapid solidification processes of NiAl have been studied. The cooling rates of 4×1013, 4×1012and 8×1011K/s are considered. The multi-body potential is used to describe the atomic interaction, the orientation order parameters and pair analysis technique are used to reveal the structural features, and the calculated results indicate that the glass transition temperature(Tg) is about 790 K. The cooling rate has great influence on the process of solidification, atthe cooling rates of 4×1013and 4×1012K/s. The structure of NiAl is amorphous at 300 K, but atthe slower rate of 8×1011K/s, the structure ofNiAl is crystalline. These results indicate the cooling rate is very importantwhen the liquid NiAl solidifies