Phase-field Simulation of the Stability of Fe<sub>2</sub>Al<sub>5</sub> Phase at Fe/molten Zn–Al Interface

The stability of η-Fe2Al5 phase at α-Fe/molten Zn–0.1Al (wt.%) (L) interface at 723 K in Fe–Zn–Al ternary system was investigated by phase-field simulations. Thin layers of intermetallic compound (IMC) phases (η, Г-Fe3Zn10, Г1-Fe5Zn21 and δ1-FeZn7) were placed between the α and L phases, and the growth of the IMC layers and the atomic diffusion of constituent elements along the direction perpendicular to the α/L interface were calculated by one-dimensional phase-field simulation. The simulation result showed that Г and Г1 phases dissolved, and thin η phase and thick δ1 phase remained stable at the α/L interface. Moreover, several phase-field simulations were performed by varying the values of interdiffusion coefficients in each phase. The simulation results showed that the diffusion and partitioning behaviors of Al have a significant effect on the stability of IMC layers at the α/L interface. It was found that the partitioning of Al to the α phase was suppressed due to the fact that the value of interdiffusion coefficient in the α phase was several orders of magnitude smaller than those in the IMC phases. The resultant Al partitioning to the IMC phases was the direct cause of the stabilization of the η phase and the destabilization of the Г and Г1 phases.