Hydrogen sorption properties of mechanically alloyed Mg1−2xFexTix powder mixtures

We report an investigation on the hydrogen sorption properties of mechanically alloyed systems of nominal composition Mg1−2xFexTix (x = 0.10, 0.15 and 0.20). The starting metallic powder mixtures were milled in H2 ambient, till a steady state with no further H2 absorption was attained. The resulting samples were then characterized and submitted to several H2 discharge-charge cycles in order to determine their hydrogen sorption properties. With the aim to investigate the dependence of these properties on the sample microstructure we also studied samples of nominal composition Mg80Fe10Ti10 obtained through different processing routes. In those samples the Fe and Ti additives were added as a fine powder mixture or as the intermetallic compound FeTi while their mechanical alloying with Mg was conducted under H2 or Ar atmosphere. All the samples were characterized by X-ray diffraction and Mössbauer spectroscopy on 57Fe, before and after their cycling in H2. The results are analyzed in the framework of possible mechanisms for the transition metals catalytic action on the H2 sorption processes and the influence of the sample microstructure.