| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface refined sintered alloy containing plate crystal tungsten carbide, improved in wear resistance as well as in breaking resistance. SOLUTION: A surface refined layer is formed having a layer thickness, at the most, of <=500μm from the surface of a sintered alloy toward the inner part of this alloy. Further, a hard refined layer, in which binding phase and plate crystal tungsten carbide are gradually decreased from the inner side of the alloy toward the surface side of the sintered alloy and which has hardness higher than that of the inner part of the alloy, exists having a layer thickness of at least >=20μm in the surface refined layer. Moreover, the inner part of the alloy consists of 5-30 vol.% of binding phase composed essentially of cobalt and/or nickel, 5-30 vol.% of plate crystal tungsten carbide of >=3 aspect ratio, and the balance hard phase composed of at least one kind selected from the group consisting of the carbides and nitrides of the group IVa, Va, VIa elements of the periodic table and mutual solid solutions thereof with inevitable impurities.
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