| 摘要 |
PURPOSE: To improve hardness, toughness, and plastic deformability by incorporating a fixed amount or more of plate crystal tungsten carbide into a sintered hard alloy. CONSTITUTION: Carbon and/or graphite is blended with a W alloy powder containing 2-30wt.% of Co and/or Ni, or further, Co, Ni, Cr, W, W2 C, WC, or W and one or more kinds among compound carbides consisting of Co, Ni, and carbon are added to the blended powder. The resulting powder mixture is mixed, compacted, and then heated in vacuum or in a nonoxidizing gas atmosphere and sintered, by which the sintered hard alloy having a composition consisting of 3-40vol.% of binding phase composed essentially of Co and/or Ni and the balance tungsten carbide can be obtained. Further, plate crystal tungsten carbide comprises >=10vol.% of the tungsten carbide in this alloy. It is preferable that, at the time of sintering the alloy, the process is constituted of two stages consisting of a stage for forming compound carbides and a stage for crystallizing plate crystal WC of 2-10μm grain size from the compound carbides.
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