The solubility of H in the -phase was measured by using a quenching technique. Pressures up to 50bar were used. A large concentration of vacancies existed on the Al-rich side of stoichiometry in this compound. The stoichiometric alloy was found to have the lowest H solubility. Both the partial molar enthalpy and the standard relative partial entropy of H were lowest at the stoichiometric composition. The observed compositional variation in the standard partial entropy was much too large to be attributed to vibrational effects. A plausible explanation was proposed in terms of configurational effects. This assumed that vacancies in the Al-rich alloys acted as sites for H-absorption.

T.Schober, J.Reinertz, W.A.Oates, H.Wenzl: Journal of the Physics and Chemistry of Solids, 1994, 55[10], 941-4