SURFACE REFINED SINTERED ALLOY AND PROCESS FOR PRODUCING THE SAME AND COATED SURFACE REFINED INTERED ALLOY COMPRISING RIGID FILM COATED ON THE ALLOY

摘要

There are disclosed a surface refined sintered alloy with a burnt surface, comprising 75 to 95 % by weight of a hard phase containing Ti, C and N as the essential components and otherwise comprising at least one of Zr, Hf, V, Nb, Ta, Cr, Mo and W and the balance of the alloy comprising a binder phase composed mainly of Co and/or Ni and inevitable impurities, wherein the sintered alloy satisfies at least one conditions selected from the group consisting of the following (1) to (3): (1) the average grain size of the hard phase in a surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.8 to 1.2-fold of the average grain size of the hard phase in the inner portion of the sintered alloy excluding the surface layer; (2) the average content of the binder phase in the surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.7 to 1.2-fold of the average content of the binder phase in the inner portion of the sintered alloy; and (3) the average hardness in the surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.95 to 1.10-fold of the average hardness in the inner portion of of the sintered alloy; and a process for producing the same.