A study of grain boundary precipitation of nano-scale Cu-rich phase in polycrystalline Fe-Cu binary alloys using a phase-field method

In this study, a phase-field model was developed to simulate quantitatively, for the first time, the precipitation process of the Cu-rich phase at grain boundaries in polycrystalline Fe-Cu alloys with different Cu contents at different aging temperatures. The results showed that, with increasing segregation of Cu atoms at grain boundaries, the incubation time of the Cu-rich phase was decreased, and the number density of the Cu precipitates increases at the boundaries but decreases within grains. With lower initial Cu content or at a higher temperature, a relatively small number of Cu precipitates could preferentially be formed at grain boundaries through a nucleation-growth mechanism. With increasing the initial Cu content or decreasing temperature, precipitation of the Cu-rich phase occurred by a pseudo-spinodal decomposition, resulting in formation of the Cu precipitates in a large number at grain boundaries and inside grains over a shorter period. This work paved the way to applying the phase-field modeling technique to further quantify the precipitation behaviors of Cu-rich phase in polycrystalline Fe-Cu alloys.