Formation of eutectic structure and de/ hydriding kinetics properties: A novel Ti-Hf-V-Mn multi-principal element alloy

The novel Ti_23-xV₄₀Mn₃₇Hf_x (x = 8 and 10 at%) multi-principal element alloys (MPEAs) were prepared using vacuum non-consumable electrode arc-melting furnace. An analysis of the hydrogen sorption process unveiled a thought-provoking discovery, shedding light on the microstructure and performance of the alloys. The MPEAs exhibited a higher abundance of the C14 Laves phase in comparison to the Ti₂₃V₄₀Mn₃₇ alloy. The C14 Laves phase underwent a transformation into columnar dendrites, resulting in the formation of a finely textured eutectic structure within the MPEAs. This distinctive microstructure endowed the MPEAs with superior activity and faster hydrogen absorption kinetics compared to the Ti₂₃V₄₀Mn₃₇ alloy. The initial hydrogen absorption process followed a nucleation and crystal growth mechanism. In addition, the Ti₁₃V₄₀Mn₃₇Hf₁₀ alloy exhibited an impressive maximum hydrogen desorption capacity of 1.96 wt%, representing a significant 38% increase when compared to the Ti₂₃V₄₀Mn₃₇ alloy. This enhanced hydrogen desorption capacity can be attributed to the presence of numerous diffusion channels for hydrogen atoms, as well as shorter diffusion distances within the MPEAs. Furthermore, the values of ΔH increased to 30.38 and 32.76 kJ/mol H₂, respectively, for the MPEAs. This indicates a higher stability of hydrides within the MPEAs.