Microstructure and First Hydrogenation Properties of Individual Phases in TiFe + 12 wt.% ZrV2 Alloy

This study investigates the microstructure and first hydrogenation properties of Fe52Ti40Zr3V5 and Fe37Ti44Zr9V10 alloys, which are individual phases present in the as-cast TiFe + 12 wt.% ZrV2 alloy (parent alloy). The parent alloy exhibited fast first hydrogenation kinetics due to the interplay of these two phases. Our objective is to study the hydrogen storage behavior of these individual phases. The samples were synthesized by arc melting and characterized by X-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The results show that when these alloys are melted separately, they do not exhibit the same phase composition as in the parent alloy, indicating a metastable state under our synthesis conditions, which significantly impacts their hydrogen storage behavior. Hydrogenation capacity was measured using a homemade Sieverts apparatus. Both alloys demonstrated excellent first hydrogenation kinetics, with an absorption capacity of 0.9 wt.% for the Fe52Ti40Zr3V5 alloy and 2.3 wt.% for Fe37Ti44Zr9V10 alloy. Our key finding is that the final crystal structure of multi-element alloys is highly dependent on the synthesis method.