密排六方金属自扩散的计算机模拟

Computer simulation study of Self-diffusion for HCP metals

应用改进分析型嵌入原子法(modified analytical embedded-atom method,MAEAM),研究了Re、Ru、Zr、Y、Co和Sc 6种密排六方(hexagonal closed-packed,HCP)金属(c/a<8/3^(1/2))单空位最近邻(NN,非基平面)、次近邻(NNN,基平面)和第三近邻(TNN,非基平面)原子自扩散机制.结果表明,3种机制能量曲线均是对称的,且能量极大值出现在迁移路径的中点.根据能量最小化原理,这6种HCP金属中单空位最可几迁移路径依次为最近邻、次近邻,第三近邻原子迁移困难.

The self-diffusion mechanism of nearest-neighbor （NN, out of the basal plane）, nextnearest-neighbor （NNN, in the basal plan） and third-nearest-neighbor （TNN, out of the basal plane） atom of vacancy in six HCP metals Re,Ru,Zr,Y,Co and Sc （c/a 〈 √8/3） have been investigated by using modified analytic embedded method. The results revealed that, for each of the three selfdiffusion mechanism, the energy curve is symmetric, and the maximum value of the energy appears at the middle point of the diffusion path. The energy minimization predicts that the favorable migrations of the mono-vacancy in the six metals are to nearest-neighbor atom, next-nearest-neighbor atom in order, while the migration of third-nearest-neighbor actom is very difficult.