To obtain a hydrogen storage alloy excellent in hydrogen occlusion characteristic and corrosion resistance by providing a rapidly solidified alloy having a specific composition and also having plural metallic phases different in crystal structure or composition.
A hydrogen storage alloy is a rapidly solidified alloy having a composition represented by general formula AaRbTcMd and also having plural metallic phases different in crystalline structure or composition. At this time, A is one element among Ti, Zr, and Hf, R is one element among La, Ce, Pr, Nd, and Y, T is one element among Ni, Co, Fe, Cu, Mn, and Cr, M is one element among Al, Si, Ga, Ge, Zn, Sn, In, and Sb, and the symbols (a), (b), (c), and (d) satisfy, by atomic %, 30≤a≤70, 0≤b≤30, 10≤c≤60, 5≤d≤30, and a+b+c+d=100, respectively. Further, preferred average crystalline grain size of the alloy is in the range between 10nm and 50/μm. By this method, the nickel- hydrogen secondary battery, excellent in high-efficiency electric discharge characteristic, can be provided.
KAWASHIMA FUMIYUKI
SAKAMOTO TOSHIYA
