On the iron-vacancy-hydrogen system

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