A method of producing a cubic boron nitride sintered material includes: forming an organic cubic boron nitride powder by attaching an organic substance onto a cubic boron nitride source material powder; preparing a powder mixture including more than or equal to 85 volume % and less than 100 volume % of the organic cubic boron nitride powder and a remainder of a binder source material powder by mixing the organic cubic boron nitride powder and the binder source material powder, the binder source material powder including WC, Co and Al; and obtaining the cubic boron nitride sintered material by sintering the powder mixture.

Provided is a coated cutting tool having improved wear resistance and fracture resistance and a prolonged tool life. The coated cutting tool includes a substrate and a coating layer formed on the substrate. The coating layer includes a first layer containing Ti(C.sub.x1N.sub.1-x1) and a second layer containing (Ti.sub.1-y1Al.sub.y1)N, particles in the first layer have an average particle size of 5 nm or more and less than 100 nm, 1.0≤I(111)/I(200)≤20.0 in the first layer, the first layer has an average thickness of 5 nm or more and 1.0 μm or less, 0.1≤I(111)/I(200)≤1.0 in the second layer, particles in the second layer have an average particle size of more than 100 nm and 300 nm or less, and the second layer has an average thickness of 5 nm or more and 2.0 μm or less.

An object of the invention is to provide a coated cutting tool whose tool life can be extended by having excellent wear resistance and fracture resistance. The coated cutting tool includes: a substrate; and a coating layer formed on a surface of the substrate, in which the coating layer includes a lower layer, an intermediate layer, and an upper layer in this order from a substrate side to a surface side of the coating layer, the lower layer includes one or more Ti compound layers formed of a specific Ti compound, the intermediate layer contains TiCNO, TiCO, or TiAlCNO, the upper layer contains α-type Al.sub.2O.sub.3, an average thickness of the lower layer is 2.0 μm or more and 8.0 μm or less, an average thickness of the intermediate layer is 0.5 μm or more and 2.0 μm or less and is 10% or more and 20% or less of a thickness of the entire coating layer, an average thickness of the upper layer is 0.8 μm or more and 6.0 μm or less, and in the intermediate layer, a ratio of a length of CSL grain boundaries to a total length 100% of a total grain boundary is 20% or more and 60% or less.

A surface-coated cutting tool includes a base material and a coating formed on a surface of the base material. The coating includes a first hard coating layer including crystal grains having a sodium chloride-type crystal structure. The crystal grain has a layered structure in which a first layer composed of nitride or carbonitride of Al.sub.xTi.sub.1-x and a second layer composed of nitride or carbonitride of Al.sub.yTi.sub.1-y are stacked alternately into one or more layers. The first layer each has an atomic ratio x of Al varying in a range of 0.6 or more to less than 1. The second layer each has an atomic ratio y of Al varying in a range of 0.45 or more to less than 0.6. The largest value of difference between the atomic ratio x and the atomic ratio y is 0.05≤x−y≤0.5.

A surface-coated cutting tool includes a base material and a coating covering the base material. The base material includes a rake face and a flank face. The coating includes a TiCN layer. The TiCN layer has a (422) orientation in a region d1 in the rake face. The TiCN layer has a (311) orientation in a region d2 in the flank face.

A cutting tool comprising a substrate and a coating layer formed on the substrate, wherein the coating layer has, from a side closer to the substrate, a lower layer that contains a compound having a composition represented by (Al.sub.xTi.sub.1-x)N, and an upper layer that is formed on the lower layer and contains a compound having a composition represented by (Al.sub.yTi.sub.1-yN; the average thickness of the lower layer is 1.0 μm or more and 10.0 μm or less; the average thickness of the upper layer is 1.0 μm or more and 10.0 μm or less; and an area ratio GOS.sub.i of crystal grains having a GOS value of 1 degree or lower in the lower layer and an area ratio GOS.sub.s of crystal grains having a GOS value of 1 degree or lower in the upper layer satisfy GOS.sub.i<GOS.sub.s.

A cutting tool includes a substrate and a coating film, wherein the coating film has a first layer formed from a plurality of hard grains, the hard grains are made of TiSiCN having a cubic crystal structure, the hard grains have a lamellar structure in which a layer having a relatively high silicon concentration and a layer having a relatively low silicon concentration are alternately stacked, and a maximum value of percentage of number A.sub.Si of silicon atoms to a sum of the number A.sub.Si of silicon atoms and number A.sub.Ti of titanium atoms in a grain boundary region between the hard grains, {A.sub.Si/(A.sub.Si+A.sub.Ti)}×100, is larger than an average value of percentage of number B.sub.Si of silicon atoms to a sum of the number B.sub.Si of silicon atoms and number B.sub.Ti of titanium atoms in the first layer, {B.sub.Si/(B.sub.Si+B.sub.Ti)}×100.

A coated tool may include a base member including a first surface, and a coating layer located at least on the first surface of the base member. The coating layer may include a first layer located on the first surface and including a titanium compound, and a second layer contactedly located on the first layer and including aluminum oxide. The second layer may include an orientation coefficient Tc(0012) of 3.0 or more by X-ray diffraction analysis. The coating layer may include a plurality of voids located in a direction along an interface between the first layer and the second layer, and an average value of widths of the voids in a direction along the interface is smaller than an average value of distances between the voids adjacent to each other in a cross section orthogonal to the first surface.

Disclosed are a coated cutting tool in which a coating layer is formed and a method for making the coating layer. The coating layer of the cutting tool of the present disclosure is formed on the whole or part of a substrate, and includes an MT-TiCN layer and an α-Al.sub.2O.sub.3 layer which are formed of columnar grains. The MT-TiCN layer has texture coefficients of TC(311)>1.5 and TC(422)>1.5 and is formed of TiCN deposited by a chemical vapor deposition method within the range of 800° C. to 950° C., and the α-Al.sub.2O.sub.3 layer is formed of columnar grains and has TC(006)>4. The coating layer of the present disclosure may form a coating layer (coating) having excellent wear resistance and chipping resistance by depositing, an α-Al.sub.2O.sub.3 layer having a strong orientation in a <001> crystallographic direction with excellent adhesion, without using an HT-TiCN layer as in the related art.

Provided is a coated cutting tool having improved wear resistance and fracture resistance and a long tool life. The coated cutting tool include a substrate and a coating layer formed on the substrate, wherein the coating layer has an alternately laminated structure of a first layer and a second layer, the first layer contains a compound having a composition represented by (Al.sub.aM.sub.bTi.sub.1-a-b, wherein M represents at least one of a Mo element and a W element, and 0.75≤a≤0.90 and 0.00<b≤0.20 are satisfied, the second layer contains a compound having a composition represented by (Al.sub.cM.sub.dTi.sub.1-c-d)N, wherein M represents at least one of a Mo element and a W element, and 0.75≤c≤0.90 and 0.00≤d≤0.20 are satisfied, the compound contained in the second layer being different from the compound contained in the first layer, at least one of a and c is 0.80 or more and, and an average thickness of the alternately laminated structure is 0.5 μm or more and 5.0 μm or less.