Regulating the microstructure and hydrogen storage properties of Ti23V40Mn37 + 10 wt% ZrNi alloys via ultrasonic treatment

To improve the activation performance and kinetic property of the Ti23V40Mn37 + 10 wt% ZrNi alloy, ultrasonic treatment was applied during its solidification. Besides, the effect of microstructure evolution on the hydrogen storage properties was investigated. Both as-cast and ultrasonically-treated (UST) Ti23V40Mn37 + 10 wt% ZrNi alloys were composed of BCC, C14 Laves and β-Zr phases. BCC phases appeared to be dendritic-shaped, of which the lattice parameter increased and the dendritic trunk was refined from 13.5 μm to 5.0 μm by ultrasonic processing. Hydrogen ab-/desorption rate accelerated and the maximum hydrogen desorption capacity was improved to 1.52 wt% at 303 K, owing to the increasing number of grain boundaries formed. The apparent dehydriding activation energy of the UST alloy decreased to 32.530 kJ/mol, while its dehydriding enthalpy (ΔH) enlarged to 40.22 kJ/mol H2 due to the lowered stability of the hydride.