Microscopic phase-field study of the effect of temperature on the pre-precipitates of Ni–Al–Cr alloy

Abstract

The pre-precipitation process of Ni–Al–Cr alloy is studied using the microscopic phase-filed dynamic model. It is found that prior to the formation of DO22 (Ni3Cr) ordered phase, a pre-precipitated phase with L10 (M=1) structure appears first, temperature plays significant effect on the pre-precipitated phase with L10 (M=1) structure. With increasing temperature, the incubation period and existent time of L10 (M=1) pre-precipitated phase are prolonged, the formation of DO22 ordered phase is delayed. The equilibrium value of the occupation probability (OP) of Cr atom decreases at β site, but it increases at α1, α2, and α3 sites. By contrast, the occupation probabilities of Al atom decreases at α1 site, but it increases at β, α2, and α3 sites. With the temperature increasing, the maximum value of OP of Cr atom at α3 site is decreased, the ordered degree of L10 (M=1) pre-precipitated phase is decreased.