Role of magnetism in the decomposition of $\alpha$-Fe-Cu alloy

Recent ab initio studies of the role of magnetism in the decomposition of $\alpha$-Fe-Cu alloy are analyzed. It is shown that the calculations based on effective pair potentials obtained earlier in the framework of the partial disordered-local moment model strongly overestimate the magnetic contribution. A simple model with the ab initio parametrization is formulated. It allows us to calculate the solubility limits for the bcc and fcc copper precipitates in $\alpha$-Fe, which are in good qualitative agreement with the experimental data.