Cemented carbide and cutting tool

Abstract

This invention relates to a superhard alloy comprising a first hard phase, a second hard phase, and a bonding phase. The first hard phase is composed of a plurality of tungsten carbide particles. The second hard phase is composed of at least one first compound selected from the group consisting of TiNbC, TiNbN, TiNbCN, TiTaC, TiTaN, TiTaCN, TiTaNbC, TiTaNbN, and TiTaNbCN. The bonding phase contains at least 50% by mass of cobalt. The first hard phase of the superhard alloy, ... The total content of the aforementioned second hard phase and the aforementioned bonding phase is 94% by volume or more; the content of the aforementioned first hard phase of the aforementioned superhard alloy is 75.0% by volume or more and 97.0% by volume or less; the content of the aforementioned second hard phase of the aforementioned superhard alloy is 0.1% by volume or more and 5.0% by volume or less; the content of the aforementioned bonding phase of the aforementioned superhard alloy is 4.0% by volume or more and 15.0% by volume or less; the standard deviation (sd) of the Heywood diameter of the aforementioned tungsten carbide particles, measured by volume, is 0.1 μm by volume or more and 0.25 μm by volume; the percentage of the aforementioned second hard phase with a diameter of 0.2 μm or less relative to the total number of the aforementioned second hard phases is 1% by volume or more and 10% by volume; the percentage of the aforementioned second hard phase with a diameter of 0.8 μm or more relative to the total number of the aforementioned second hard phases is 1% by volume or more and 10% by volume. A cemented carbide includes a first hard phase at a content of 75.0 vol% or more and 97.0 vol% or less, composed of a plurality of tungsten carbide particles, a second hard phase at a content of 0.1 vol% or more and 5.0 vol% or less, composed of at least one first compound selected from the group consisting of TiNbC, TiNbN, TiNbCN, TiTaC, TiTaN, TiTaCN, TiTaNbC, TiTaNbN, and TiTaNbCN, and a binder phase at a content of 4.0 vol% or more and 15.0 vol% or less, containing cobalt at 50 mass% or more, a total content of the first hard phase, the second hard phase, and the binder phase in the cemented carbide is 94 vol% or more, a standard deviation sd of Heywood diameters of the tungsten carbide particles in the particle size distribution on a volume basis is 0.1 μm or more and 0.25 μm or less, a percentage of the number of the second hard phases having a diameter of 0.2 μm or less relative to the number of all of the second hard phases is 1% or more and 10% or less, and a percentage of the number of the second hard phases having a diameter of 0.8 μm or more relative to the number of all of the second hard phases is 1% or more and 10% or less.

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