To obtain an alloy having good initial characteristics and improved characteristics of the discharging rate of a battery (rate characteristics) at a low cost without deteriorating the characteristics of the service life (cycle characteristics) by composing the compsn. of an AB5 type alloy contg. no Co and contg. Fe of the specified nonstoichiometric one (B site-rich) and allowing it to have a CaCu5 type crystal structure of a specified structure contg. a certain amt. of V.
This AB5 type hydrogen storage alloy having a crystal structure of a CACu5 type expressed by the formula of MmNiaMnbAlcFedCueVf is obtd. by heating and melting a hydrogen storage alloy raw material, subjecting it to casting and thereafter thereafter executing heat treatment, and the heat treatment is executed under the conditions of 1000 to 1100°C×1 to 6 hr. In the formula, Mm denotes misch metal, 3.95≤a≤4.3, 0.3≤b≤0.6, 0.15≤c≤0.5, 0≤d≤0.8, 0≤e≤0.3, 0.005≤f≤0.03 and 4.9≤a+b+c+d+e+f≤5.4 are satisfied, and (a) to (f) denote the molar number based on Mm 1 mol in either case.
SAKAGUCHI YOSHIKI
YASUDA KIYOTAKA
