Hydrogen ab/desorption behavior of the mechanical alloyed Ti–V–Cr–Mn–Fe HEAs with varying Mn/Cr ratio

High-entropy alloys (HEAs) have become a focal point of research in hydrogen storage, owing to their unique structural characteristics and the complex interactions among their constituent elements. This study builds upon our previous research by systematically adjusting the Cr and Mn content in Ti 35 V 35 (CrMnFe) 30 alloys to investigate their effects on hydrogen storage performance. The results indicate that increasing the Mn content reduces overall alloy distortion and formation enthalpy, effectively suppressing the formation of Laves, while simultaneously enhancing the BCC phase content and lattice constant. This adjustment increases the room temperature hydrogen storage capacity from 1.08 wt% to 1.39 wt%. Furthermore, increasing the Cr content significantly enhances the alloy's activation performance by lowering the initial hydrogen absorption temperature, and the surface reactions and interfacial processes activation energy. However, a higher Cr content induces greater lattice distortion, which hinders the nucleation, growth of the metal hydrides, and increases the activation energy for these stages. Despite this, all mechanically alloyed HEAs demonstrate superior activation performance and relatively lower hydrogen absorption/desorption activation energy compared to traditionally arc-melted alloys, due to the formation of nanocrystalline structures for the mechanically alloyed alloys. • Nanocrystalline structures reduce the Ea for the first stage of hydrogenation. • The addition of Cr lowers the initial hydrogen absorption temperature of the alloy. • Interstitial solid solution mechanism ensures excellent cycling performance.