| abstract |
The sintered compact which has alumina crystal grains and zirconia crystal grains as a main component contains zirconia crystal grains and a tetragonal crystal grain. In addition, the total number of zirconia crystal grains in the range of 10 micrometers of the arbitrary cut surfaces of a sintered compact is set to N pieces, and the number a of 1st zirconia crystal grains which are surrounded by only zirconia crystal grains with respect to N pieces, When the ratio of each of the number b of the second zirconia crystal particles surrounded by only the alumina crystal particles and the number c of the third zirconia crystal particles surrounded by the zirconia crystal particles and the alumina crystal particles is set to A to C, 0% ≦ A ≦ 3%, 3% ≦ B ≦ 22% and 77% ≦ C ≦ 96% are also satisfied. In addition, N is a value of 140 or more. |