Alloying of Mg/Mg2Ni eutectic by chosen non-hydride forming elements: Relation between segregation of the third element and hydride storage capacity

Eutectic mixture Mg-11.3 at.% Ni was modified by elements X from the 13th (Al, Ga, In) and 14th group (Si, Ge, Sn and Pb). Phase analysis and distribution of X between primary solid solution Mg-Ni-X and Mg2Ni-X compound was carried out in stabilization annealed samples before hydrogen charging and in hydrided state. In the both states, it was found that X prefers Mg2Ni-X to Mg-Ni-X solid solution, and that the preference is stronger in the hydrided state. The effect is more pronounced for elements X from the 13th group. Suggested explanation was based on influence of X on the formation enthalpy of hydrides. It was observed that In increases the hydrogen storage capacity of the eutectic mixture. The most likely explanation is based on a strong segregation of In to phase Mg2Ni-X, and on a weak tendency of In to form phases with Mg and Ni. (C) 2011 Elsevier B.V. All rights reserved.