First-principles study of vacancy formation and migration in clean and Re-doped γ′-Ni3Al

Using density functional theory calculations in conjunction with the climbing images nudged elastic band method, we studied the vacancy formation and migration in clean and Re-doped Ni3Al. Both the chemical potential of the species and the magnetic effect are considered to determine the vacancy formation energy. We also simulated the vacancy migration in a complete set of migration paths. The evaluated vacancy formation energy and activation energy for the motion of vacancy compared well with the experimental results. Also, the obtained migration ways for the diffusion of Ni and Al atoms are consistent with previous theoretical predictions and experimental observations. Magnetism is found to influence both the vacancy formation and migration. Our results reveal that Re doping can inhibit the formation of Ni vacancies but facilitate the formation of Al vacancies, and can also inhibit the migration of neighboring vacancies. While the doped Re atom on the Al site is stable, the Re atom on the Ni site can diffuse within the Ni-sublattice mediated by Ni vacancies.