Sintered body and cutting tool using the same

Abstract

The present invention provides a sintered body that can maintain room-temperature toughness while increasing room-temperature strength more than conventional materials, and a cutting tool using the same. [Solution] This is a cermet-based sintered body having a core-rim structure in which hard particles mainly composed of Ti(C,N) are bonded with a high-melting-point metal. It consists of a core phase made of hard particles, a rim phase surrounding the core phase mainly composed of (Ti,W,Re)(C,N), and an alloy phase made of W-Re, exhibiting a compressive strength of 4500 MPa or more at room temperature.

Claims

1. A cermet-based sintered body having a core-rim structure in which hard particles mainly composed of Ti(C,N) are bonded together with a high-melting-point metal, A sintered body characterized by comprising three phases: a core phase made of hard particles, a rim phase surrounding the core phase and mainly composed of (Ti, W, Re)(C, N), and an alloy phase made of W-Re, exhibiting a room-temperature compressive strength of 4500 MPa or more.

2. The sintered body according to claim 1, characterized in that it consists only of the three phases and does not contain any composite compounds other than those composed of Ti(C,N) and (Ti,W,Re)(C,N).

3. The sintered body according to claim 1 or 2, characterized in that it has a component composition containing 40 to 70% by mass of W and Re combined.

4. The sintered body according to claim 3, characterized in that the mass ratio of W to Re is W:Re = 70:30 to 80:

20.

5. The sintered body according to claim 1, wherein the core phase has an alloy composition comprising 10 to 20 atomic percent of carbon atoms, 20 to 40 atomic percent of nitrogen atoms, and 0.5 to 3.0 atomic percent of oxygen atoms, with the remainder being titanium atoms and unavoidable impurities.

6. The sintered body according to claim 1, wherein the rim phase has an alloy composition comprising 15 to 25 atomic percent of carbon atoms, 3 to 20 atomic percent of nitrogen atoms, 10 to 25 atomic percent of watts, 0.3 to 1.0 atomic percent of renitride atoms, and 0.5 to 3.0 atomic percent of oxygen atoms, with the remainder being titan atoms and unavoidable pure substances.

7. The sintered body according to claim 1, wherein the Re atom concentration in the alloy phase is 10 to 40 atomic percent.

8. The rim phase has a Re-rich layer at its interface with adjacent rim phases, which has a higher Re atom concentration and a thickness of less than 25 nm compared to other regions of the rim phase. The sintered body according to claim 1, wherein the Re concentration of the Re-rich layer is higher than the maximum value of the Re concentration in a region that is linear and at least 25 nm inside the interface of adjacent rim phases, as determined by TEM-EDS line analysis.

9. A cutting tool comprising a cermet-based sintered body having a core-rim structure in which hard particles mainly composed of Ti(C,N) are bonded together with a high-melting-point metal, The sintered body is characterized by comprising three phases: a core phase made of hard particles, a rim phase surrounding the core phase and mainly composed of (Ti, W, Re)(C, N), and an alloy phase made of W-Re, and exhibiting a room-temperature compressive strength of 4500 MPa or more.

10. The cutting tool according to claim 9, characterized in that the sintered body does not contain any composite compounds other than those composed of Ti(C,N) and (Ti,W,Re)(C,N), and consists only of the three phases.

11. The cutting tool according to claim 9 or 10, characterized in that the sintered body has a component composition containing 40 to 70% by mass of W and Re combined.

12. The cutting tool according to claim 9, characterized in that the mass ratio of W to Re is W:Re = 70:30 to 80:20.

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