Hydriding and dehydriding characteristics of Mg-LaNi5 composite materials prepared by mechanical alloying

The hydriding and dehydriding kinetics of composite materials with the nominal composition Mg-x wt.% LaNi5 (x=10, 20, 30) prepared by mechanical alloying of the components in a planetary mill with an acceleration of 12 g have been investigated. It has been shown that the addition of LaNi5 improves the absorption-desorption characteristics of magnesium towards hydrogen, the best achievements belonging to the composite containing 30 wt.% LaNi5. The data obtained on the changes occurring in the phase composition of the samples as a result of hydrogen cycling and available information from the literature have been used to explain the behaviour of the materials during hydriding. Comparison with results on composites with the same nominal composition obtained by other methods shows that mechanical alloying ensures preparation of samples with favourable kinetic characteristics which are hydrided under the softest possible conditions. (C) 1998 Elsevier Science S.A.