Theoretical study of hydrogen solubility in Fe, Co and Ni

A higher order regular solution model developed previously by the authors has already been extensively applied in the prediction of the amorphous formation area of rapidly quenched ternary alloys. As only the chemical interaction among the randomly distributed substitutional atoms is considered, the original model can only be applied to calculate the mixing enthalpy of the substitutional metallic solid and liquid solutions. In the present study, the model has been extended to include the exchange interaction between the collinear magnetic moments of the atoms and the chemical interaction between the nonmetallic atoms on the interstitial sites and the ferromagnetic atoms on the regular sites. The extended model has been successfully applied to investigate the dependency of hydrogen solubility on temperature and magnetization in the transition metals Fe, Co and Ni near the Curie point.