Provided is a coated cutting tool having a base material side single layer portion and a laminated portion provided as a hard coating in order from a base material side. The base material side single layer portion is formed of a nitride-based hard coating in which a proportion of Al is highest among metal (including metalloid) elements, a sum of Al and Cr in a content ratio (atomic ratio) is 0.9 or more, and at least B is contained. In the laminated portion, a nitride-based a layer in which a proportion of Ti is highest among metal (including metalloid) elements and at least B is contained, and a nitride-based b layer in which a proportion of Al is highest among metal (including metalloid) elements and at least Cr and B are contained are alternately laminated.

A coated cutting tool is provided which allows for satisfactory machining over a long period of time, particularly in the machining of difficult-to-machine materials with low thermal conductivity. The coated cutting tool includes a substrate and a coating layer formed on a surface of the substrate, wherein: at least one layer of the coating layer comprises a predetermined layer containing a compound having a composition represented by the formula: (Al.sub.XTi.sub.1-X)N [wherein x denotes an atomic ratio of the Al element based on a total of the Al element and the Ti element, and x satisfies 0.60≤x≤0.85]; a value of an orientation index TC (311) of a cubic (311) plane of the predetermined layer is from 2.5 or more to 4.2 or less; and an average thickness of the predetermined layer is from 1.0 μm or more to 12.0 μm or less.

A coated cutting tool is provided which allows for satisfactory machining over a long period of time, particularly in the machining of difficult-to-machine materials with low thermal conductivity. The coated cutting tool includes a substrate and a coating layer formed on a surface of the substrate, wherein: at least one layer of the coating layer comprises a predetermined layer containing a compound having a composition represented by the formula: (Al.sub.XTi.sub.1-X)N [wherein x denotes an atomic ratio of the Al element based on a total of the Al element and the Ti element, and x satisfies 0.60≤x≤0.85]; a value of an orientation index TC (311) of a cubic (311) plane of the predetermined layer is from 2.5 or more to 4.2 or less; and an average thickness of the predetermined layer is from 1.0 μm or more to 12.0 μm or less.

A coated cutting tool, comprising: a substrate; and a coating layer formed on a surface of the substrate, wherein the coating layer includes a lower layer and an upper layer in this order from the substrate side toward the surface side of the coating layer, and the upper layer is formed on a surface of the lower layer, the lower layer contains a compound having a composition represented by (Al.sub.xTi.sub.1-x)N, an average thickness of the lower layer is 1.0 μm or more and 15.0 μm or less, the upper layer contains an α-Al.sub.2O.sub.3 layer containing α-Al.sub.2O.sub.3, an average thickness of the upper layer is 0.5 μm or more and 15.0 μm or less, and in the α-Al.sub.2O.sub.3 layer, a texture coefficient TC (1, 1, 6) of a (1, 1, 6) plane is 2.0 or more and 6.0 or less.

A diamond tool includes a diamond at least on a cutting edge including one or two or more diamond grains including a diamond phase composed of a diamond crystal structure and a graphite phase composed of a graphite crystal structure. When a ratio I.sub.π*/I.sub.σ* between an intensity of a π* peak derived from a π bond of carbon in the graphite phase and an intensity of a σ* peak derived from a σ bond of carbon in the graphite phase and a σ bond of carbon in the diamond phase is determined for the diamond grain by measuring an energy loss associated with excitation of K-shell electrons of carbon by electron energy loss spectroscopy, the ratio I.sub.π*/I.sub.σ* of the diamond grain on a surface of the cutting edge is 0.1 to 2 and a ratio I.sub.π*/I.sub.σ* of the diamond grain at a depth position of 0.5 μm from the surface of the cutting edge is 0.001 to 0.1.

A diamond tool includes a diamond at least on a cutting edge including one or two or more diamond grains including a diamond phase composed of a diamond crystal structure and a graphite phase composed of a graphite crystal structure. When a ratio I.sub.π*/I.sub.σ* between an intensity of a π* peak derived from a π bond of carbon in the graphite phase and an intensity of a σ* peak derived from a σ bond of carbon in the graphite phase and a σ bond of carbon in the diamond phase is determined for the diamond grain by measuring an energy loss associated with excitation of K-shell electrons of carbon by electron energy loss spectroscopy, the ratio I.sub.π*/I.sub.σ* of the diamond grain on a surface of the cutting edge is 0.1 to 2 and a ratio I.sub.π*/I.sub.σ* of the diamond grain at a depth position of 0.5 μm from the surface of the cutting edge is 0.001 to 0.1.

A coated tool of the present invention includes a base material and a hard coating film on the base material. The hard coating film is a nitride or carbonitride containing aluminum (Al) of 65 atomic % or more 90 atomic % or less, titanium (Ti) of 10 atomic % or more 35 atomic % or less, a total of aluminum (Al) and titanium (Ti) of 85 atomic % or more, and argon (Ar) of 0.20 atomic % or less. The hard coating film satisfies a relationship of Ih×100/Is≤12 when a peak intensity of a (010) plane of AlN of a hexagonal close-packed structure is Ih and a sum of peak intensities due to predetermined nine crystal planes of TiN and AlN is Is in an intensity profile obtained from a selected area diffraction pattern of a transmission electron microscope.

A coated tool of the present invention includes a base material and a hard coating film on the base material. The hard coating film is a nitride or carbonitride containing aluminum (Al) of 65 atomic % or more 90 atomic % or less, titanium (Ti) of 10 atomic % or more 35 atomic % or less, a total of aluminum (Al) and titanium (Ti) of 85 atomic % or more, and argon (Ar) of 0.20 atomic % or less. The hard coating film satisfies a relationship of Ih×100/Is≤12 when a peak intensity of a (010) plane of AlN of a hexagonal close-packed structure is Ih and a sum of peak intensities due to predetermined nine crystal planes of TiN and AlN is Is in an intensity profile obtained from a selected area diffraction pattern of a transmission electron microscope.

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.

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.