| 摘要 |
PROBLEM TO BE SOLVED: To improve the electrode reaction activity and alkali resistance of an alloy by specifying the ratio of the number of rare earth elements and also the ratio of the number of cobalt atoms, respectively, between the inner part and surface part of the grain of the alloy having a composition consisting of rare earth elements, elements including Ni and Co, etc. SOLUTION: With respect to a grain represented by composition formula ABx (4.4<=x<=5.5 is satisfied, A is one or >=2 kinds among rare earth elements, and B contains at least Ni and Co and can further contain at least one element, of a type endothermic at the time of hydrogen absorption, selected from the group consisting of Cu, Fe, Sn, Si, Al, W, Mn, Zn, Cr, Mo, In, and Ga), the ratio of the number of rare earth elements (a fixed quantity of misch metal is counted as one atom of rare earth element), per unit area, in the surface part of the grain at a depth of <=2 nm from the grain surface to the number of rare earth elements, per unit area, in the inner part of the grain at a depth of >=100 nm from the grain surface is regulated to 0.3-2.0. Simultaneously, ratio of the number of cobalt atoms, per unit area, between the inner part and surface part of the grain is regulated to 0.8-3.0. |
