Nitrogen-containing sintered hard alloy

摘要

PCT No. PCT/JP94/00158 Sec. 371 Date Mar. 28, 1995 Sec. 102(e) Date Mar. 28, 1995 PCT Filed Feb. 3, 1994 PCT Pub. No. WO94/18351 PCT Pub. Date Aug. 18, 1994A nitrogen-containing sintered hard alloy in which the content of the binder phase is at the highest level in an area to a depth of between 3 mu m and 500 mu m from its surface and its content in this area is between 1.1 and 4 times the average content of the binder phase in the entire alloy. Below this area, the content of the binder phase decreases gradually so that its content becomes equal to the average content of the binder phase at a depth of 800 mu m or less. The content of the binder phase in the surface layer is 90% or less of its maximum value. The depth of 800 mu m is a value at which the thermal conductivity is kept sufficiently high and at the same time a tool can keep high resistance to plastic deformation during cutting.