Hydrogen sorption properties of an Mg–Ti–V–Fe nanocomposite obtained by mechanical alloying

Abstract

The absorption–desorption characteristics with respect to hydrogen of a magnesium-based nanocomposite obtained by high-energy ball milling have been investigated. The composite contains 5 wt.% (∼3at.%) Ti, 10 wt.% (∼5.5 at.%) V and 10 wt.% (∼5 at.%) Fe, of which the former two transition metals only form a binary hydride. It has been shown that at 623 K the composite may be hydrided up to a very high absorption capacity whose values remain appropriate for practical purposes even at much lower hydriding temperatures. Part of the iron present in the composite has been found to interact with magnesium and hydrogen under the hydriding conditions, the ternary hydride Mg 2FeH 6 being formed. Its presence in the composite-hydrogen system has been assumed to be responsible for the reduced rate of hydrogen desorption from the particle surfaces and for some peculiarities of the composite behaviour during hydriding.