Gas atomization processing of designed dual-phase intermetallic hydrogen storage alloys

Two dual-phase nickel–metal hydride (Ni–MH) battery powders for battery applications were produced by gas atomization. They are characterized by a fine and uniform dispersion of rare-earth (RE)-containing second phase in the Zr-containing base alloy, achieved from gas atomizing molten mixtures of AB2 and AB5 alloys. The dual-phase alloy formulations were (AB2)100−x(AB5)x, where x is 1 and 5. The new dual-phase alloys were found to have high C-rate discharge capacities. Crushing and annealing the dual-phase powders improved the discharge capacity of as-gas atomized powder. C- and C/8-rate discharge capacities of 383 and 425 mAh g−1 (or power density of 134 and 148 Wh kg−1), respectively, were measured for the crushed and annealed dual-phase MmZr05 alloy powder. The possible commercial powder production of the Ni–MH battery powder using a gas atomization process was demonstrated. Four 500 lbs lots of a Zr-based AB2 alloy were successfully gas atomized in a pilot gas atomizer unit. The discharge capacities of this powder after processing exhibited 349 and 414 mAh g−1 at C- and C/8-rate discharges, respectively.