Patent ID: 7501207

Claim:
A hydrogen absorbing alloy, comprising: a composition represented by general formula (3) given below and contains not higher than 10% by volume including 0% by volume of a phase having an AB 2 type crystal structure, and an intensity ratio calculated by formula (2) given below being lower than 0.15 including 0: I 1 /I 2 (2) where I 2 is an intensity of a highest peak in a X-ray diffraction pattern using a CuKα ray, and I 1 is an intensity of a highest peak appearing at a value of 2θ falling within a range of from 8° to 13° in the X-ray diffraction pattern, θ being a Bragg angle; R 1-a-b Mg a T b Ni Z-X M3 X (3) where R is at least one element selected from rare earth elements, said rare earth elements including Y, T is at least one element selected from the group consisting of Ca, Ti, Zr and Hf, M3 is at least one element selected from the group consisting of Co, Mn, Fe, Al, Ga, Zn, Sn, Cu, Si, B, Nb, W, Mo, V, Cr, Ta, Li, P and S, the atomic ratios of a, b, X and z are respectively satisfy conditions of: 0.15≦a≦0.37, 0≦b≦0.1, 0.53≦(1−a−b) ≦0.85, 0≦X≦2 and 3≦Z≦4.2, wherein a parallel growth region precipitates in at least one crystal grain of a principal phase, and the parallel growth region has a crystal structure differing from a crystal structure of the principal phase.