Effect of Re in γ phase, γ′γ′ phase and γ/γ′γ/γ′ interface of Ni-based single-crystal superalloys

Abstract Molecular dynamics (MD) within the framework of the embedded atom method and the first-principles discrete variational method (DVM) are both used to study the effect of Re in the γ phase, the γ ′ phase and the γ / γ ′ interface of Ni-based single-crystal superalloys. From the MD relaxation it is found that the γ / γ ′ interface only has two atomic configurations, i.e. a coherent region and a misfit dislocation region, and the “cage-like” misfit dislocation networks, consist of 〈 1 1 0 〉 {0 0 1} edge dislocations winding over the precipitate phase. The MD results also show that the substitution atom Re stabilizes both the γ phase and the γ ′ phase, and influences the degree of mismatch between γ and γ ′ . From the simulation results we find that Re atoms have a tendency to cluster in both the γ phase and the γ ′ phase. Based on the MD simulation we have chosen six clusters of the γ / γ ′ interface for the DVM study, in which the interatomic energy, the charge distribution, the partial density of states and the electron density difference are all calculated. It is found that a Re atom occupying either a Ni site in the γ phase or an Al site in the γ ′ phase can strongly enhance the bonding strength between Re and its nearest neighboring atoms, suggesting that the substitution atom Re will influence dislocation motion along the γ / γ ′ interface.