To improve the hydrogen absorbing characteristics and corrosion resistance of an alloy by adding the group IVa and/or VIII to an intermetallic compound using rare earth elements and Ni as the base and regulating the alloy compsn. and to furthermore improve the battery capacitance and service life therein by using this alloy as the negative pole of the battery.
This alloy has a compsn. expressed by the general formula of (R1-aMa)2(Ni1-bM'b)7±α, and in which the grain size lies in the range of 1 to 100μm, where, in the formula, R denotes at least one kind of element selected from La, Ce, Sm, Nd, Pr and Y, and M' denotes one or more kind of element selected from Co, Fe, Cr, Mn, Cu, Al, Ga, Si, Ge, Sn, V, Nb, Ta, Mo, W and Zn. Furthermore, by atomic ratio, 0≤a≤0.5, 0≤b≤0.3 and α≤0.5 are satisfied. This alloy can be produced by ordinary casting, but, it is preferable that the molten metal is injected onto a high speed moving cooling body, which is cooled at a cooling rate of ≥100°C/min to refine the grain size, and after that, soaking heat treatment is executed.
KAWASHIMA FUMIYUKI
INABA TAKAMICHI
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