Addition of 3d-metals with formation of nanocomposites as a way to improve the hydrogenation characteristics of Mg 2Ni

Abstract

The hydrogen absorption–desorption characteristics of a composite material containing 85 wt.% Mg 2Ni, 10 wt.% V and 5 wt.% Ti, obtained by mechanical alloying in a planetary mill under argon have been investigated. The experimental data on the kinetics of hydriding and dehydriding and the absorption capacity values established at various temperatures and hydrogen pressures have been compared with those of a previously studied composite obtained by the same method but containing no titanium. It has been shown that the presence in the composite of a second hydride-forming 3d-metal leads to an enhanced absorption capacity and improved hydriding and dehydriding kinetics. The 85 wt.% Mg 2Ni–10 wt.% V–5 wt.% Ti composite has shown a significant hydrogen absorption at room temperature. The improved characteristics of the Ti-containing composite are attributed to the formation, along with Mg 2NiH 4 and VH x , of a third hydride, TiH x , which increases the interface and facilitates both nucleation and back diffusion of hydrogen from the sample.