First-principles study of the effects of Sr segregated on Al grain boundary

The atomic and electronic structures of an Al grain boundary with segregated Sr (substitutional) impurity atoms have been calculated by the first-principles pseudopotential method based on the local density functional theory. The results show that the boundary expands and the charge density decreases significantly over the whole boundary due to Sr segregation. This suggests grain boundary weakening, which should be responsible for the experimentally observed Sr-induced Al intergranular embrittlement.