Temperature influence on early precipitation process of Ni-Al-Fe alloy

A ternary microscopic phase-field kinetic model was used to investigate the early γ′ precipitation process of Ni₇₅Al₁₅Fe₁₀ alloy by simulating the evolution of the atomic morphology, calculating long-range order parameters and concentration, and characterizing the curve of site occupation of Fe atoms at different lattice sites in the γ′ phase at annealed temperatures 973, 1173, 1253 K. The results show, while the temperature increasing, γ′ precipitation mechanism of Ni₇₅Al₁₅Fe₁₀ alloy is transformed from the congruent ordering and spinodal decomposition to non-classic nucleation and growth; the incubation period of the γ′ phase is prolonged; Fe atoms more and more difficultly occupy the B-site (the corner site of fcc) and the occupation probability gradually decreases. The precipitated γ′ phase (L1₂ structure) is a kind of the complex Ni₃(Al_1-xFe_x) single-phase.