Composite structure and hydrogen storage properties in Mg-base alloys

In order to improve the hydrogen absorption/desorption kinetic properties of Mg and Mg–Ni alloys, composite hydrogen storage alloys in the form of powder and film have been synthesized and investigated. For fabricating the composite powder, Mg or Mg–Ni powder was mechanically alloyed with MmNi3.5(CoAlMn)1.5MmNi3.5(CoAlMn)1.5 alloy. For the preparation of the film with a composite structure, evaporation deposition and magnetron sputtering methods have been used to fabricate Mg–Ni film with multi-phase structure and Mg/Mm–Ni and Mg–Ni/Mm–Ni multi-layer film. By controlling the fabrication process, the microstructure feature, such as phase constituent, grain size, interlayer distances, interlayer boundary structure, of the composite can be modified. To reveal the influence of the composite structure on the hydrogen absorption/desorption kinetic properties of Mg and Mg–Ni alloys, hydrogen storage properties of the composite were measured with their microstructure features varied systematically. The present work shows that the hydrogen sorption properties of Mg and Mg–Ni-based alloys can be substantially improved by forming composites having proper microstructure features.