Phase-field modeling of effect of Ni on formation and phase transformation of Cu-rich phase in Fe–Cu–Ni alloys

A phase-field model integrated with the thermodynamic databases was constructed to investigate the impact of Ni content on the precipitation kinetics and phase transformation of the Cu-rich phase in Fe–Cu–Ni alloy at 773 K. The results demonstrated that the Cu core–Ni shell structures form via the decomposition of Cu–Ni co-clusters, which is consistent with previous experimental results. As the Ni content increases, both the volume fraction and number density of Cu-rich precipitates increase, while their size decreases. With the increase in Ni content, the transformation from α Cu to 9R Cu is accelerated, which is the opposite to the result of increasing Mn content. Magnetic energy can increase the nucleation rate of the Cu-rich phase, but it does not affect the phase transformation driving force required for its crystal structure transformation.