Alpha/gamma equilibria in the Fe-Co phase diagram

It is possible to treat the equilibrium between alpha and gamma phases and obtain a good representation of the phase boundaries in the Fe-Co system us ing the cluster variation method. In this study, calculations were performe d on quaternary Fe+Fe-Co+Co- by considering both chemical and magnetic inte ractions. The A2/B2 order-disorder transition and the alpha/gamma phase equ ilibria agree well with the experimental data. These results were obtained with very few adjustable parameters; however, the study is a first step tow ard calculating multicomponent phase diagrams based on the Fe-Co system.