Microscopic phase-field simulation of the early precipitation mechanism of Ni₃Al phase in Ni-Al alloys

The precipitation mechanism and morphological evolution of Ni₃Al phase is studied on the atomic scale with the microscopic phase-field simulation. The results show that the early precipitation mechanisms are different for the alloys with different Al content. The early precipitation mechanism of lower Al concentration alloy is the mechanism of non-classical nucleation growth, the medium Al concentration alloy is the mixed mechanism of non-classical nucleation growth and spinodal decomposition and the higher Al concentration alloy is the mechanism of congruent ordering followed by spinodal decomposition.