Hydrogen storage properties of nanocrystalline Mg1.9Ti0.1Ni made by mechanical alloying

The mechanical alloying technique was used to make nanocrystalline Mg2Ni and Mg1.9Ti0.1Ni powders. Their hydrogen storage properties were characterized and compared with that of polycrystalline Mg2Ni made by casting. It was found that the ball milled Mg2Ni and Mg1.9Ti0.1Ni can absorb hydrogen at 473 K in the first cycle rapidly without prior activation. The nanocrystalline Mg1.9Ti0.1Ni showed the best kinetics, followed in order by mechanically alloyed Mg2Ni and cast Mg2Ni. Mg1.9Ti0.1Ni absorbs more than 3 wt% H-2 in 2000 s at 423 K while the mechanically alloyed and the cast Mg2Ni do not form hydride at this temperature. Partial substitution of Mg by Ti reduced the activation energy of desorption from 69 kJ mol(-1) for nanocrystalline Mg2Ni to 59 kJ mol(-1) for Mg1.9Ti0.1Ni. (C) 1999 Elsevier Science S.A. All rights reserved.