Effect of compositional tuning on the hydrogen storage performance of dual-phase TiVCrMnFe high-entropy alloys

High-entropy alloys (HEAs) represent promising candidates for solid-state hydrogen storage due to their high hydrogen storage capacity potential and enhanced chemical tunability. In this work, a series of dual-phase Ti 35 V 35 Cr x Mn y Fe 5 ( x / y = 1/4, 2/3, and 4/1) HEAs were designed to explore the influence of elemental tuning on microstructure and hydrogen storage performance. Reducing the Cr/Mn ratio increased the C14 Laves phase fraction, leading to a dual-phase microstructure. An optimal balance between the C14 Laves phase fraction and the BCC lattice parameter favored hydrogen absorption, resulting in a non-monotonic variation in hydrogen absorption capacity. The maximum capacity of 3.19 wt% at 25 °C was achieved for the alloy with a Cr/Mn ratio of 2:3. Furthermore, incorporation of C14 Laves phase into the BCC matrix significantly enhanced hydrogenation kinetics and reversibility. The Ti 35 V 35 Cr 5 Mn 20 Fe 5 alloy, which contains the highest fraction of the C14 Laves phase among the designed alloys, reaches 90% of its maximum absorption capacity within 44 s at 25 °C and achieves a reversible hydrogen capacity of 1.59 wt% at 75 °C, with desorption enthalpy of 34.35 ± 1.66 kJ/mol and desorption entropy of 98.93 ± 7.32 J/(mol·K). Additionally, during the cycling test, the Ti 35 V 35 Cr 5 Mn 20 Fe 5 alloy, which exhibited lower lattice distortion, retained 91.6% of its hydrogen capacity after 50 absorption/desorption cycles. These findings clarify the relationships among composition, structure, and properties and guide the development of high-performance Ti-V-based HEAs for practical hydrogen-storage applications.