Multi-component phase-field simulation of microstructural evolution and elemental distribution in Fe-Cu-Mn-Ni-Al alloy

A quinary phase-field model coupled with CALPHAD thermodynamic data was developed to simulate diffusion-controlled phase decomposition in the Fe-Cu-Mn-Ni-Al alloy system during isothermal aging. The effects of Ni/Al concentrations and magnetic interactions on the kinetics of Cu-rich phase formation and component distribution features were systematically studied. Simulated atom maps indicate that the Cu-rich phase possessed a complex core shell structure consisting of a BCC Cu-rich core and a B2 Ni/Al/Mn-rich shell. Ni/Al/Mn-rich shells could be regarded as a buffer layer hindering Cu cluster formation and also as a diffusion channel connecting neighboring small particles, thus influencing the precipitation of the Cu-rich phase. It was found from the analyses of volume fraction and particle size distribution that the deviation between the proposed coarsening law and the theoretical LSW theory occurred due to the inhibiting effect of Ni-Al-Mn shells and the mixed coarsening mechanism of coalescence and Ostwald ripening. High Ni/Al contents and magnetic interactions obstructed the phase separation, growth and coarsening of the Cu-rich phase, thus leading to particle refinement and the clustering of Ni-Al-Mn atoms. Therefore, the obtained results can provide useful information for the preparation of Fe-Cu-Mn-Ni-Al alloy.