Estimation of γ/γ′ diffusion mobility and three-dimensional phase-field simulation of rafting in a commercial nickel-based superalloy

The diffusion mobility associated with γ/γ′ interface migration (γ/γ′ diffusion mobility) in a nickel-based superalloy is estimated on the basis of the database of multicomponent atomic diffusion mobility. The estimation is based on the assumption that the phase equilibrium is reached during high-temperature creep, and that the γ/γ′ interface migration is controlled by atomic diffusion of Re, which exhibits the smallest atomic diffusion mobility in the alloy system under consideration. Utilization of the estimated γ/γ′ diffusion mobility enabled a three-dimensional phase-field simulation of microstructure-dependent heterogeneous creep in the γ matrix phase, directional coarsening of the γ′ precipitate (rafting), and macroscopic creep responses. The estimation of γ/γ′ diffusion mobility is assumed to be effective for quantitatively analyzing the rafting kinetics during high-temperature creep by the phase-field simulation.