Role of magnetism in Cu precipitation inα-Fe

Abstract

The temperature-dependent solubility of Cu in $\ensuremath{\alpha}$-Fe and initial stages of Cu precipitation are investigated in first-principles calculations and statistical thermodynamic and kinetic modeling based on ab initio effective interactions. We demonstrate that the weakening of the phase separation tendency with increasing temperature, especially close to the magnetic phase transition, is related to the strong dependence of the ``chemical'' interactions on the global magnetic state. At the same time, our calculations demonstrate that the vibrational contribution obtained in the quasiharmonic approximation is relatively small for temperatures near the Curie point. The results of Monte Carlo simulations of Cu solubility and clustering are in good agreement with experimental data.