Phase-field study on effects of antiphase domain and elastic energy on evolution of γ′ precipitates in nickel-based superalloys

The effects of the antiphase domain (APD) and the elastic energy on the morphology evolution of γ′ precipitates in Ni-Al binary alloy during aging process are studied with the phase-field method. The merging-splitting phenomenon between the two neighboring γ′ precipitates is observed. The changes of γ′ area fraction and average γ′ size are analyzed for different APDs and for different elastic energies, respectively. It is shown that the merging-splitting phenomenon may occur when the radii of neighboring γ′ precipitates with different APDs are smaller than 24 nm and the critical size for the merged γ′ precipitate splitting is about 108 nm. Besides, the coarsening of γ′ precipitates is significantly impeded by the APDs but accelerated by the elastic energy, and the change of average γ′ size can be divided into two stages with different mechanisms.