Relationship between microstructure and hydrogenation properties of Ti0.85Zr0.15Mn1.5V0.5 alloy

The hydrogenation properties of Ti0.85Zr0.15Mn1.5V0.5 alloy for four different microstructures obtained by as-cast arc melting, high-temperature annealing, ball-milling, and recrystallization after milling, have been determined. The as-cast alloy reaches a hydrogen content of 1 H/M with absorption kinetics of less than 10 s at room temperature. Sloping plateau pressures are obtained for as-cast, and annealed arc-melted alloys due to the persistence of chemical heterogeneity. Mechanical milling causes formation of amorphous phase, and improves chemical homogeneity. Milled alloy exhibits no plateau pressure, a lower hydrogen capacity (0.7 H/M), and slower kinetics. Annealing of the milled alloy at 800 °C for 30 min restores the hydrogenation capacity up to 1 H/M with a flat plateau pressure, and fast kinetics. Mechanical milling is an efficient method to obtain a chemically homogenous alloy. Subsequent annealing of the milled alloy produces homogeneous AB2 crystalline phase.