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

The absorption-desorption characteristics with respect to hydrogen of a mag nesium-based nanocomposite obtained by high-energy ball milling have been i nvestigated. The composite contains 5 wt.% (similar to 3at.%) Ti, 10 wt.% ( similar to5.5 at.%) V and 10 wt.% (similar to5 at.%) Fe, of which the forme r 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 capacit y 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 conditio ns, the ternary hydride Mg2FeH6 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. (C) 2001 Elsevier Science B.V. All rights reserved.