| abstract |
A cBN sintered compact for an end mill obtained by sintering mixed powder prepared by mixing about 35 to 50 percent by volume of cubic boron nitride powder smaller than about 2 µm in average particle size with about 50 to 65 percent by volume of a binder under cBN-stable superhigh pressure conditions. The binder contains about 20 to 30 percent by weight of Al and one or more Ti compounds selected from a group of TiN 2 , Ti(C,N) 2 , TiC 2 , (TI,M)C 2 , (Ti,M)(C,N) 2 and (Ti,M)N, (where M indicates a transition metal element of the group IVa, Va or Vla of the periodic table excepting Ti and z is within a range of about 0.7 ≦ z ≦ about 0.85) and the atomic ratio of Ti contained in the binder to the transition metal element of the group IVa, Va or Via of the periodic table excepting Ti is about 2/3 to 97/100 while the total tungsten concentration of tungsten contained in the form of at least one of tungsten carbide or the Ti compound described above in the binder is about 5 to 20 percent by weight. |