INFLUENCE OF ELEMENTAL DIFFUSION ON LOW-TEMPERATURE FORMATION OF MGH2IN TIMN1.3T0.2-MG (T EQUALS 3D-TRANSITION ELEMENTS)

In order to examine the influence of the elemental diffusion from the host compound into the Mg region on low temperature formation of MgH2, we have investigated the hydriding properties and the microstructures of the composite materials TiMn1.3T0.2-Mg (T = V, Cr, Mn, Fe, Co, Ni and Cu). MgH2 is formed at 353 K in all composite materials. Of all th e substitutions, the amount of MgH, is the largest in the case of the Cu substitution, which originates from the existence of the Mg-Mg2Cu e utectic formed by Cu diffusion from the host compound TiMn1.3Cu0.2 int o the Mg region during the liquid phase sintering. In addition, the hy drogen capacity of TiMn1.3Cu0.2-Mg (that is TiMn1.3Cu0.1-(Mg+Mg2Cu) af ter the sintering) easily saturates in comparison with TiMn1.5-(Mg+Mg2 Cu) without Cu diffusion. It is concluded that Cu diffusion promotes t he mobility of hydrogen atoms at the complex interface between the hos t compound and the Mg region.