Rafting and redissolution of γ' phase in Ni-Al alloy under external stress.

The volume fraction and rafting degree of the γ'-NiAl phase under stress and high temperature are the key characteristics of mechanical properties in Ni-based superalloys, the rafting and redissolution of γ' phase caused by the creep at high temperature damage the morphology and properties of Ni-based superalloys. The phase-field simulation is performed to study the rafting accompany with the redissolution of γ' phase under high temperature and loading stress in Ni-Al alloy, the driving force and kinetics evolution of the γ' rafting were revealed. During the rafting under continuous heating, the elastic energy in the vertical γ channel is different to that of the horizontal γ channel, this difference in elastic energy drives the elements diffusion directionally to form the γ' rafts morphology.