A theoretical study, based upon density functional theory, was made of the interaction of vacancies with a tilt grain boundary. The grain boundary volume expansion and vacancy-induced contraction were calculated, and compared for nearest-neighbor atoms. The former was found to be smaller than the latter. The formation energies of vacancies in various layers of the grain boundary were calculated. It was found that it required more energy to form a vacancy at the boundary plane than in the bulk; although the remainder of the grain-boundary region attracted vacancies. The microscopic mechanisms of grain-boundary sliding and migration were investigated; with and without vacancies. It was found that, although a vacancy could hinder grain boundary motion by tripling the energy barrier to sliding and migration, it could not inhibit or delay migration. A vacancy which was placed in the first layer from the interface was found to be trapped in the layer and was unable to follow the migrating interface.

Interaction of Vacancies with a Grain Boundary in Aluminium - a First-Principles Study. G.Lu, N.Kioussis: Physical Review B, 2001, 64[2], 024101 (7pp)