Cu_3Au中空位及其迁移机制的计算机模拟

STUDY OF VACANCIES AND THEIR MIGRATION MECHANISMS IN Cu_3Au BY COMPUTER SIMULATION

采用Finnis-Sinclair类型的多体势模型,用分子动力学方法对L1_2 型有序金属间化合物Cu_3Au中的单、双空位进行了计算机模拟研究.选取了空位的三种可能的迁移方式,计算了单、双空位的迁移激活能.这三种迁移方式是:最近邻空位跳跃、一组由相关的六步最近邻跳跃构成的空位循环运动和次近邻空位跳跃.计算了单空位的形成能和双空位的结合能.讨论了对扩散起主要作用的微观机制.所得计算结果与实验值符合得很好.

The molecular dynamics method is employed to simulate mono-vacancy and divacancy in the ordered intermetallic compound Cu3Au with L12 structure using Finnis-Sinclair type many-body potentials. Calculations of the migration energies of mono-vacancies and divacancies by three possible ways of migration are presented. The ways considered were: nearest-neighbor vacancy jumps, cyclic vacancy motion by a correlated set of six nearest-neighbor jumps, and next-nearest-neighbor vacancy jumps. The formation energies of mono-vacancies and the binding energies of divacancies have been calculated. The micromechanisms which play a major role in diffusion have been discussed. The results of calculations are found to be in good, agreement with the experimental measurements.