Reversible hydriding in YFe2-xAlx (x = 0.3, 0.5, 0.7) intermetallic compounds

Abstract

To restrain the irreversible disproportionating reaction of YFe2 phase in the hydrogenation process, the structure of YFe2 was modified by partly substituting Fe with Al. And then, the hydrogen storage properties of YFe2-xAlx (x = 0.3, 0.5, 0.7) alloys were systematically investigated. It was found that the C15 Laves phase structure of those three Y-Fe-Al alloys kept stable at different states of as-annealed, hydrogenated and dehydrogenated, but their lattice constants vary with the Al and hydrogen contents. The YFe1.7Al0.3 alloy shows maximum reversible hydrogen storage capacity of 1.38 wt%, which is lower than its initial hydrogen absorption capacity of 1.56 wt%. All the three Y-Fe-Al alloys show fast hydrogenation rate at relative low temperature of 100 °C, however, their dehydrogenation properties are still limited due to their rather low desorption equilibrium pressure. The present finding provides a possibility of developing new types of rare earth-transition metal alloys for hydrogen storage.