Hydriding/dehydriding properties of magnesium-ZrCr2 composites

Composites of Mg and the intermetallic compound (IMC) ZrCr2 have been prepared by mechanical alloying. The crystallographic structure. composition and morphology of the composites were analysed by means of X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX). XRD patterns show that no alloy formation takes place during milling. EDX data show that milling time is a key parameter to control the morphology of the composites. Short milling times of 10 min give composites with the IMC attached to the Mg particle surface, while it is irregularly distributed in the Mg bulk for longer milling times of 70 min. Hydriding/dehydriding properties of the composites were studied by the solid-gas reaction method. Composites with a distribution of the IMC in the Mg bulk are easily activated and show faster hydriding/dehydriding kinetics than untreated Mg, which indicates that ZrCr2 acts as a catalytic compound for the M.-hydrogen reaction. (C) 2002 Elsevier B.V. All rights reserved.