By combining molecular dynamics simulations with a modified analytic embedded-atom method potential, the formation, migration and activation energies were calculated for 4 types of migration of Cu vacancies and 3 types of migration of Ag vacancies in Cu–Ag immiscible alloy system. The equilibrium concentration of Cu vacancies was greater than that of Ag vacancies due to the formation energy of the Cu vacancy (1.012eV) being lower than that of the Ag vacancy (1.169eV). Comparing the migration or activation energy needed for the 4-fold migration of a Cu vacancy and 3-fold migration of a Ag vacancy showed that the favored migration mechanism was the nearest-neighbor jump for a Cu vacancy, while the straight [010] 6-jump cycle applied to the Ag vacancy. The activation energy of the nearest-neighbor jump of a Cu vacancy (2.164eV) was lower than that of the straight [010] 6-jump cycle of the Ag vacancy (2.404eV), thus making the former more favorable. It was concluded that the primary migration mechanism was the nearest-neighbor jump of an abundance of Cu vacancies.

Atomistic Study of Self-Diffusion in Cu–Ag Immiscible Alloy System. J.M.Zhang, G.X.Chen, K.W.Xu: Journal of Alloys and Compounds, 2006, 425[1-2], 169-75