Cubic boron nitride sintered body and cutting tool
A cBN sintered body contains cBN particles whose proportion is 85-97% by volume, and a binding phase whose proportion is 3-15% by volume. The cBN sintered body contains Al whose ratio to the entirety of the cBN sintered body is 0.1-5% by mass, and Co whose mass ratio to the Al is 3 to 40, and includes Al 3 B 6 Co 20 .
1. A cBN sintered body, comprising:
cBN particles whose proportion is 85-97% by volume; and
a binding phase whose proportion is 3-15% by volume,
wherein an Al content in the cBN sintered body is 0.1-5% by mass,
wherein a ratio of a Co content to the Al content (Co/Al) is 3 to 40 in terms of mass ratio, and
wherein the cBN sintered body includes Al 3 B 6 Co 20 .
2. The cBN sintered body according to claim 1 , wherein a ratio of peak strength of a strongest peak of the Al 3 B 6 Co 20 to peak strength of cBN (111) is 0.02-0.25 in an X-ray diffraction measurement.
3. The cBN sintered body according to claim 1 , wherein a ratio of peak strength of a strongest peak of the Al 3 B 6 Co 20 to peak strength of Co (200) is 0.01-0.25 in an X-ray diffraction measurement.
4. The cBN sintered body according to claim 1 , wherein a ratio of peak strength of the Co (200) to peak strength of cBN (111) is 0.5-3 in an X-ray diffraction measurement.
5. The cBN sintered body according to claim 1 , wherein no peak of AlN exists, or a ratio of peak strength of a strongest peak of AlN to peak strength of cBN (111) is 0.05 or less in an X-ray diffraction measurement.
6. The cBN sintered body according to claim 1 , wherein no peak of BCo exists, or a ratio of peak strength of a strongest peak of BCo to peak strength of cBN (111) is 0.05 or less in an X-ray diffraction measurement.
7. The cBN sintered body according to claim 1 , wherein a mean particle size of the cBN particles is 1.5-2.5 μm and a mean particle size of Al 3 B 6 Co 20 particles is 0.02-0.5 μm.
8. A cutting tool, comprising a cutting edge part composed of the cBN sintered body according to claim 1 .