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 AB2 type metal hydride Zr0.6Ti0.4Fe1Cr1. 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.