Alpha/Gamma equilibria in the Fe-Co phase diagram

It is possible to treat the equilibrium between α and γ phases and obtain a good representation of the phase boundaries in the Fe-Co system using the cluster variation method. In this study, calculations were performed on quaternary Fe+Fe-Co+Co- by considering both chemical and magnetic interactions. The A2/B2 order-disorder transition and the α/γ phase equilibria agree well with the experimental data. These results were obtained with very few adjustable parameters; however, the study is a first step toward calculating multicomponent phase diagrams based on the Fe-Co system.