Interactions between hydrogen and dislocations in aluminum: an ab initio study
The understanding of the interactions between H and dislocations in metals is of considerable importance due to the influence of these effects on plastic flow and H mobility. In this paper we employ the semidiscrete variational Peierls-Nabarro model to study the core properties of various dislocations in Al with and without H impurity. The material-specific parameters, including elastic constant and generalized stacking fault energy surface entering the model are calculated from the density functional theory with a large supercell to simulate the low concentration of H impurity (less than 5 at. dislocation core properties, including core width, core energy, Peierls stress and cross-slip energy barrier are calculated with and without H impurity and the interactions between H and dislocations are then revealed. We also calculate the binding energy of H at dislocation core as a function of dislocation character and find that the more the edge component, the larger the binding energy. Significant reductions in Peierls stress of various dislocations have been observed when H in present, supporting the H-enhanced local plasticity (HELP) theory.