Electronic structure and multi-scale behaviour for the dislocation-doping complex in the gamma phase of nickel-base superalloys

Abstract

By using the lattice Green-function multiscale method, the equilibrium geometry of the edge dislocation in the γ matrix was obtained and the electronic structure changes due to the addition of refractory elements Re, W and Ta were analysed. The results indicate that the orbital hybridization takes place during the interaction between dislocation and doping atoms, among which the hybridization between dislocation and Re is the most complicated. On the macroscopic level, the critical resolved shear stress of the γ matrix containing dislocation-doping complex was predicted at T = 0 and 78 K from first-principles calculations. Considering the distribution of the doping elements between two phases, the remarkable strengthening effect of Re in Ni-base superalloys can be ascribed to a combination of the strong partitioning to the γ phase and the strong chemical interactions with dislocation.