Initial hydrogenation in multiphase TiFeCoNiCu high-entropy alloy for hydrogen storage

Abstract

Research on hydrogen storage utilizing hydride-forming alloys has recently gained impetus owing to the hunt for clean and sustainable alternative energy sources. Because of elemental substitution-induced lattice strain, traditional intermetallic compounds such as LaNi5 and TiFe have demonstrated better hydrogen-storage characteristics; however, their practical use at room temperature (RT = 25 °C) remains challenging. This study investigates the hydrogen-storage ability of a multicomponent high-entropy alloy (HEA) based on TiFe, i.e., TiFeCoNiCu HEA, for hydrogen-storage applications. The fabrication of the HEA was accomplished by mechanical alloying for 45 h. The activation behavior of first hydrogenation of the obtained TiFeCoNiCu HEA was studied at room temperature and 10 atm H2 pressure. Results indicated that the TiFeCoNiCu HEAs absorbed hydrogen by forming dominating face-centered-cubic (FCC), and C14 Laves hydrides with a maximum amount of hydrogen absorption up to 1.3 wt.% at 25 °C. The hydrogenation characteristics of the TiFe-based HEAs improved owing to their high mixing entropy and substantial lattice distortion effects. The findings of this study could aid in the development of future hydrogen-storage systems that are both useful and highly efficient in hydrogen-storage applications.