Phase field modeling the growth of Ni₃Al layer in the β/γ diffusion couple of Ni-Al binary system

The growth behavior of Ni₃Al phase layer in the β/γ diffusion couple of Ni-Al binary system, including the shape evolution and growth kinetics, have been simulated by using the KKS multiphase field model. Simulation results indicate that, when Ni₃Al layer growth is controlled completely by volume diffusion, it could be regarded as parabolic growth. However, if the fast grain boundary diffusion is taken into account, the growth rate of Ni₃Al phase is accelerated, and the growth kinetics deviates from parabolic growth, which is consistent with experiments and other simulation results. Simulation results also demonstrate some details of shape evolution of grains, such as the uneven Ni₃Al/γ and Ni ₃Al/β interfaces and the grain boundary migration of Ni ₃Al grains caused by fast grain boundary diffusion.