Microscopic phase-field simulation of the heat treatment process for Al-Zr intermetallic compound

The aging processes of three different component Al-Zr alloys of Al-3at% Zr, Al-6at%Zr and Al-15at%Zr were simulated through the microscopic phase-field dynamic model. The results indicate that the precipitation mechanisms of the Al₃Zr ordered phase of Ll₂ structure are the spinodal decomposition, the mixed mechanism of spinodal decomposition and non-classical nucleation, and the non-classical nucleation for the Al-3at% Zr, Al-6at%Zr and Al-15at%Zr alloys, respectively. The ordered phase is in the order of supersaturated solid solution, G.P. zone, nonstoichiometric ordered phase, and stoichiometric ordered phase. At the initial stage of evolution, the smaller GP. zone of lower concentration dissolved but the larger GP. zone of higher concentration grew up to form an ordered phase at last.