HYDRIDING BEHAVIOR OF GAS-ATOMIZED AB(5) ALLOYS

The hydriding characteristics of some AB(5) alloys produced by high pr essure gas atomization (HPGA) have been examined during reactions with hydrogen gas, and in electrochemical cells. The hydrogen storage capa cities and the equilibrium pressures for HPGA processed LaNi5, LaNi4.7 5Sn0.25, and MmNi(3.5)Co(0.8)Al(0.4)Mn(0.3) alloys (where Mm denotes M ischmetal) are found to be nearly identical to annealed alloys produce d as ingots. The large discontinuous volume change across the alpha-be ta plateau region for gas-atomized LaNi5Hx was seen to produce extensi ve fracturing in all but the smallest alloy spheres. However, only the largest spheres of the gas-atomized MmNi(3.5)Co(0.8)Al(0.4)Mn(0.3) an d LaNi4.75Sn0.25Hx alloys exhibited any discernible fracturing. The ma ximum electrochemical storage capacities of the gas-atomized LaNi4.75S n0.25 and MmNi(3.5)Co(0.8)Al(0.4)Mn(0.3) alloys were found to be small er than the capacities of annealed alloys prepared from ingots.