Phase-field simulation with the CALPHAD method for the microstructure evolution of multi-component Ni-base superalloys

In order to simulate multi-component diffusion in a Ni-base superalloy using the phase-field method, the Gibbs free energy of the γγ and γ′γ′ phases in the quaternary Ni–Al–Re–Ta superalloy system was linked to the CALPHAD method using a four-sublattice model. The free energy curve and phase equilibrium compositions in this work were in good agreement with the results of the Thermo-calc calculation, indicating that the model was successfully linked to the CALPHAD method. A one-dimensional phase-field simulation showed a pileup of Re at the γ/γ′γ/γ′ interface during the growth of precipitates as well as a spike of the Re concentration in a γ′γ′ phase, accompanied by precipitate coalescence.