Oxidation and compositional modulation in single phase C14 Zr0.6Ti0.4Fe1Cr1 alloy

This study investigates the effects of heat treatment on the crystal structure and hydrogen absorption behavior of the AB 2 type metal hydride Zr 0.6 Ti 0.4 Fe 1 Cr1. The objective is to understand how 3- and 6-day heat treatments at 1000°C influence the alloy's microstructure and hydrogenation properties. Using electron microscopy, EBSD analysis, X-ray diffraction, and hydrogenation measurements, we found that the as-cast alloy exhibits rapid hydrogen absorption with significant compositional variations due to segregation during casting, confirmed by a single C14 Laves phase in XRD. Heat treatment slowed hydrogen absorption and reduced hydrogen capacity, with XRD indicating the structure remained primarily C14 Laves phase. However, SEM/EDS analysis showed substantial microstructural changes, including the emergence of new phases and segregation of Zr-rich phases, likely non-hydride forming, influenced by elevated oxygen content. These new phases probably contribute to the reduced hydrogen uptake capacity. • The crystal structure of Ti 0.4 Zr 0.6 Fe 1 Cr 1 AB 2 alloy was investigated in both as-cast and heat-treated states. • C 14 phase shows compositional variations due to limited elemental diffusivity during casting • As-cast alloy with concentration modulation shows rapid hydrogen uptake • Heat treatment at 1000°C retains Laves phase structure but causes phase decomposition and microstructure changes. • Elevated oxygen content influences new non-hydride phase formation, affecting capacity in heat-treated alloys