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

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 L1(0) (M = 1) structure appears first, temperature plays significant effect on the pre-precipitated phase with L1(0) (M = 1) structure. With increasing temperature, the incubation period and existent time of L1(0) (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 beta site, but it increases at alpha(1), alpha(2), and alpha(3) sites. By contrast, the occupation probabilities of Al atom decreases at alpha(1) site, but it increases at beta, alpha(2), and alpha(3) sites. With the temperature increasing, the maximum value of OP of Cr atom at alpha(3) site is decreased, the ordered degree of L1(0) (M = 1) pre-precipitated phase is decreased. (C) 2014 Elsevier B.V. All rights reserved.