Ni3Al合金液态与非晶中的原子团簇

采用常温常压分子动力学模拟技术，模拟了液态Ni3Al中原子团簇在快速凝固条件下的演变过程，模型采用的是TB(tight binding)作用势.用偶分布函数、键对和多面体等结构参数来描述快速凝固条件下团簇种类和数量的变化，并将团簇结构可视化.在2 000 K下，液态Ni3Al中团簇数量较少，且都是由缺陷二十面体构成；在4×1013 K•s－1的冷速下，团簇的数量随温度的降低不断增加，且出现完整二十面体团簇，体系最终形成了由二十面体和缺陷二十面体团簇网络所组成的非晶结构.

Atom Clusters in Liquid and Amorphous of Ni3Al Alloy

A series of simulation of the evolution of atom clusters in liquid Ni3Al alloy during rapid solidification have been performed under constant pressure and temperature by molecular dynamic simulation technique. TB(tight binding) potential function has been adopted to describe the interaction between atoms. The structure parameters such as pair correlation function, bonded pairs and polyhedra clusters have been used to characterize the dependence of the type and number of clusters on temperature during rapid cooling process. The cluster structure could be visualized clearly through the conversion of atom coordinates obtained by simulation to three dimension graphical interface. The number of liquid Ni3Al clusters at the temperature of 2 000 K is small and all are made up of diicosahedron; however, it increases rapidly at the cooling rate of 4×1013 K•s－1, and finally,the icosahedra clusters occur at low temperature. The network consists of the icosahedra and diicosahedra clusters forming an amorphous system.