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.sub.3B.sub.6Co.sub.20.

A rotary cutting blade material has an attaching structure forming portion that is to serve as an attaching portion to the shank, a cutting structure forming portion that is to serve as a cutting blade, and a joint portion. The cutting structure forming portion has a core portion and a surface portion provided on the attaching structure forming portion with the joint portion being interposed, and the surface portion covers at least a part of a surface of the core portion. The attaching structure forming portion includes a hard material including a hard component and one or two or more types of iron group elements, and the hard material has a Young's modulus of not more than 350 GPa. The core portion includes a cemented carbide material, and the surface portion includes PCD or CBN.

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.sub.3B.sub.6Co.sub.20.

Methods for large-scale additive manufacturing of high-strength boron nitride nanotubes (BNNT)/aluminum (Al) (e.g., reinforced Al alloy) metal matrix composites (MMCs) (BNNT/Al MMCs), as well as the BNNT/Al MMCs produced by the large-scale additive manufacturing methods, are provided. A combination of ultrasonication and spray drying techniques can produce good BNNT/Al alloy feedstock powders, which can be used in a cold spraying process.

A cBN sintered body including cBN and a binder phase, wherein a content ratio of the cBN is 80 to 94 volume %, a content ratio of the binder phase is 6 to 20 volume %, the binder phase contains a metal phase, a V compound, and an Al compound, the metal phase contains one or more selected from the group consisting of Ni, and a Ni-containing alloy and solid solution, the Ni-containing alloy and solid solution each contain Ni and one or more elements selected from the group consisting of Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, and Co, the V compound contains one or more selected from the group consisting of VN, VCN, and VC, the Al compound contains one or more selected from the group consisting of Al.sub.2O.sub.3, AlN, and AlB.sub.2, a maximum peak position 2 of a 200 plane of the metal phase is less than 51.60, and I.sub.1/(I.sub.1+I.sub.2) is 0.40 to 0.80, where I.sub.1 denotes an X-ray diffraction peak intensity of a 220 plane of the V compound, and I.sub.2 denotes an X-ray diffraction peak intensity of a 200 plane of the metal phase.

A cubic boron nitride sintered material of the present disclosure includes 35 to 100 volume % of a cubic boron nitride grain and 0 to 65 volume % of a binder, wherein: a lattice constant of the cubic boron nitride grain is 3.6140 to 3.6161 , a silicon content in the cubic boron nitride grain is 0.02 mass % or less, and the binder material includes at least one selected from a group consisting of a compound and a solid solution of the compound, the compound consisting of at least one element selected from a group consisting of a group 4 element, a group 5 element, a group 6 element in the periodic table, aluminum, silicon, iron, cobalt and nickel, and at least one element selected from a group consisting of carbon, nitrogen, boron and oxygen.

A cubic boron nitride sintered material includes cubic boron nitride and a binder. The binder includes a first material and a second material. The first material is one or two or more first chemical species each including at least one first metallic element selected from the group consisting of tungsten, cobalt, and aluminum. Each of the first chemical species is a metal, an alloy, an intermetallic compound, a compound, or a solid solution. The second material is one or two or more second chemical species each including at least one second metallic element selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, and chromium. Each of the second chemical species is a solid solution derived from at least one selected from the group consisting of nitride, carbide, and carbonitride. In each of the second chemical species, 0.1 atom % to 10 atom % of aluminum is dissolved.

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.sub.3B.sub.6Co.sub.20.