Abstract:
The self-diffusion mechanism of nearest-neighbor (NN, out of the basal plane), next-nearest-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 self-diffusion 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.
