The stability of precepitates and the role of lattice defects in Fe-1at%Cu-1at%Ni-1at%Mn alloy: A phase-field model study

In the first part of this study, the stability of Cu precipitates, up to 2 nm in diameter, in Fe-1at%Cu-1at%Ni-1at%Mn system was evaluated within the framework of phase-field modeling by utilizing a thermodynamic database. The implanted precipitates either in isolated or in clustered arrangements, were unstable and dissolved into the matrix. The dissolution rate decreases with increasing precipitate size; however, it is strongly influenced by the spatial arrangements of the implants and the overall alloy content. In the second part, the precipitation/segregation behavior at a circular dislocation, and square prismatic loops was parametrically studied. While precipitates formed at the dislocation loop, a significant segregation of Cu was observed at prismatic loops with either vacancy or interstitial character. Although, the both types of prismatic loops provide the spatial evolution of the stress-fields with the same absolute magnitude, the vacancy loops appears to be stronger sinks and their sink strength increases with decreasing loop size. The results clearly show the necessity of inclusion of the underlying lattice defects in the microstructure modeling of materials under the irradiation environments.