Hydriding and dehydriding properties of Mg₂Ni/Ni and Mg₂ Ni/Ni + 5 wt.% Cu prepared by mechanical alloying

Elemental powders of Mg, Ni and Cu are subjected to high-energy ball milling in order to produce alloys of nominal compositions Mg₂Ni and Mg₂Ni_0.95Cu_0.05. Nanocrystalline phases based on the Mg₂Ni structure are produced after 21 hours of milling. As-milled powders were hydrided for 5 min at temperatures of 373, 423 and 473 K, under hydrogen pressures of between 0.69 and 2.07 MPa. The mass loss of the hydrided powders during thermogravimetric analysis was associated with hydrogen release. Maximum amounts of H2 release of 2.9 and 3.1 wt.% were obtained, respectively, for the Mg₂Ni and Mg₂Ni_0.95Cu_0.05 samples hydrided at 473 K without prior activation. These are some of the most advantageous results ever reported concerning the behavior of the Mg₂Ni phase as a hydrogen storage material.