| 摘要 |
A hydrogen absorbing alloy for an alkaline storage battery having a crystal structure of a CaCu5 type and represented by a composition formula MmNixCoyMnzM1-z (in the formula, M is at least one element selected from aluminum Al and copper Cu, x is a composition ratio of nickel Ni and satisfies 3.0 </= x </= 5.2, y is a composition ratio of cobalt Co and satisfies 0 </= y </= 1.2, and z is a composition ratio of manganese Mn and satisfies 0.1 </= z </= 0.9, with the proviso that the sum of x, y, and z satisfies 4.4 </= x + y + z </= 5.4) is so adapted as to have a surface region and a bulk region covered with the surface region and satisfy the condition of a/b >/= 1.2, letting a be the sum of the respective abundance ratios of atoms Ni, Co, and Mn in the surface region and letting b the sum of the respective abundance ratios of atoms Ni, Co, and Mn in the bulk region. <IMAGE> |
