Interaction of vacancies with a grain boundary in aluminum: A first-principles study - art. no. 024101

We present a theoretical study of the interaction of vacancies with a tilt grain boundary in aluminum based on the density functional theory. The grai n boundary volume expansion and vacancy induced contraction are calculated and compared for the nearest-neighbor atoms, and the former is found to be smaller than the latter. The formation energy of a vacancy placed at variou s layers in the grain boundary has been calculated and we find that it cost s more energy to form a vacancy at the boundary plane than in bulk, althoug h the rest of the grain boundary region does attract vacancies. The microsc opic mechanisms of grain boundary sliding and migration are investigated th oroughly with and without a vacancy. We find that although the vacancy can hinder the grain boundary motion by tripling the energy barrier of sliding and migration, it cannot inhibit or even delay the migration process. The v acancy placed at the first layer from the interface is found to be trapped at the layer and not able to follow the migrating interface.