Hydriding and dehydriding characteristics of mechanically alloyed LaMg17Ni composite material

A composite material with the nominal composition LaMg17Ni was synthesized by mechanical alloying and the hydriding/dehydriding (H/D) behaviors of this material were studied at several temperatures. This material has a hydrogen storage capacity (5.76% H-2, mass fraction) lower than conventionally alloyed La2Mg17(6.63% H-2, mass fraction) without activation but shows a superior hydriding/dehydriding kinetic property. At 523 K it absorbed 4.97% (mass fraction) in less than 1 min, approximately 100 times faster than La2Mg17 alloy under the same conditions. This attractive kinetic property of the alloy can be ascribed to the catalytic action of Mg2Ni, LaH2 and La as well as the multiphase structure formed in the preparation processes. The relationships between the equilibrium plateau pressure and the temperature can be expressed as lgp(eq)=-2797/T+4.267 (553 Kless than or equal toTless than or equal to623 K) for hydriding and lgp(eq)=3957/T+6.063(553 Kless than or equal toTless than or equal to623 K) for dehydriding.