First-principles investigation of the alloying effect of refractory elements Ta and W in the misfit dislocation core of γ/γ′ (0 0 1) interface

By use of first-principles DMol method based on density functional theory, we investigated the alloying effect of refractory elements such as Ta and W in a/2 [1 1 0] (0 0 1) misfit dislocation core of the γ/γ′ interface in single-crystal Ni-base superalloys. The energetic calculations show that both the refractory elements can stabilize the a/2 [1 1 0] (0 0 1) misfit dislocation core. The analysis of the electronic structure indicates that there is charge accumulation between the refractory impurity atom and the neighboring Ni atoms, and the strong bonds between refractory impurities and Ni atoms are mainly due to the hybridization of impurity d-Ni d orbitals. The introduction of the two refractory impurities results in a strong pinning effect on the a/2 [1 1 0] (0 0 1) misfit dislocation motion in the γ/γ′ interface.