Patent ID: 8124553

Claim:
A composite sintered body, comprising: 20 volume % or more and 80 volume % or less of cubic boron nitride particles; and a binder, wherein: said binder comprises at least one selected from the group consisting of nitrides, carbides, borides, and oxides of Ti and elements in the groups 5a and 6a in the periodic table, and solid solutions thereof, at least one selected from the group consisting of Zr, Si, Hf, Ge, W and Co, compounds thereof, and solid solutions thereof, and a compound of Al; when said composite sintered body contains therein W and/or Co, the total weight of the W and/or Co is less than 2.0 weight %; said composite sintered body contains therein one or more of said Zr, Si, Hf and Ge (hereinafter referred to as “X”), and the amount of each of the X is 0.005 weight % or more and less than 2.0 weight % and X/(X+W+Co) is 0.01 or more and 1.0 or less; the weight of Al in said compound of Al is 2.0 weight % or more and 20.0 weight % or less; and said compound of Al is AlB 2 and/or AlN.