Phase-field Simulation of Microstructural Evolution of γ Precipitate in γ′ Matrix in Binary Ni-Al Alloys

The microstructural evolution of γ precipitates (Ni with fcc_A1 structure) in γ′ matrix (Ni3Al with L12 structure) in the binary Ni-Al alloys was studied by means of the multi-phase-field (MPF) approach. The thermodynamic driving force and diffusivities were taken from the CALPHAD databases via the TQ interface. The thermophysical parameters, interfacial energy, elastic constants, and lattice mismatch were all set to be experimental values. The morphology evolution of one, two and multi γ precipitates in γ′ matrix were analyzed via the present phase-field simulations. A splitting behavior of two close precipitates was also observed. In the case of multi γ precipitates, the shape of the precipitates is spherical at the stage of nucleation, then cuboidal during growth stage, and becomes plate like at the stage of coarsening, which shows good agreement with the experimental results.