The solubility of H in equilibrium with H2-gas at atmospheric pressure exhibits a temperature variation, in the body-centred cubic phase range, which was incompatible with the simple quasi-regular statistics expected for a dilute interstitial solid solution. This behavior was analyzed in term of a statistical model that includes the interactions between interstitial H-atoms and lattice vacancies. Good agreement was found between the model and the experimental data.

On the Iron-Vacancy-Hydrogen System. N.Z.Carr, R.B.McLellan: Journal of Physics and Chemistry of Solids, 2005, 66[6], 1074-9