Investigation of ZrFe2-type materials for metal hydride hydrogen compressor systems by substituting Fe with Cr or V

In this study, the effects of partial substitution of Fe, in the ZrFe2-system alloys, by Cr or V are presented. The two studied alloys, ZrFe1.8V0.2 and ZrFe1.8Cr0.2, have been synthesized by high frequency induction-levitation melting under inert Ar atmosphere. The induction furnace was equipped with a water-cooled copper crucible that permits the rapid solidification of the alloy after the melting. The crystal structures of the investigated alloys have been studied by the Rietveld analysis of the obtained X-ray diffraction (XRD) patterns. The microstructure has been observed by a scanning electron microscope (SEM) on polished samples of the alloys. Their hydriding properties have been studied with a high pressure Sievert's type apparatus, up to 200 bar. All pressure-composition-temperature (PCT) measurements have been obtained at 20, 60 and 90 °C. Two high temperature activation cycles have been conducted prior to PCT measurements. The results showed almost the same uptake for the alloys after identical activation and lowering of the plateau pressure in both cases.