| 摘要 |
PROBLEM TO BE SOLVED: To provide a hard metal having a gradient structure, which possesses simultaneously improved abrasion resistance, plastic-deformation resistance, chipping resistance and defect resistance by improving the toughness and hardness in the vicinity of the surface, and consequently extends the life of a cutting tool when the hard metal is used for it, and to provide a manufacturing method therefor. SOLUTION: The hard metal has a region containing 0.1-3 vol.% of a dispersed phase formed of at least one among the carboxide, nitroxide and carbonitroxide of zirconium and/or hafnium, in a field of 200μm deep toward the inner part from the surface; and has a region containing the dispersed phase in an amount of 1/2 or less of the amount in the above region containing the dispersed phase, in a filed of 1.0 mm or deeper from the surface. The manufacturing method includes a step of oxidizing a powder compact during sintering. COPYRIGHT: (C)2007,JPO&INPIT
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