A coating includes a first base layer including a nitride of at least Al and Cr, a second base layer including a nitride of at least Al and Cr overlying the first base layer, and an outermost indicator layer overlying the second base layer. The first base layer has a positive residual compressive stress gradient. The second base layer has substantially constant residual compressive stresses. The outermost indicator layer includes a nitride of Si and Me, wherein Me is at least one of Ti, Zr, Hf, and Cr. The outermost indicator layer has residual compressive stresses that are less than the residual compressive stresses of the second base layer.

A surface-coated cutting tool includes a substrate and a coating film that coats the substrate, wherein the coating film includes a hard coating layer constituted of a domain region and a matrix region, the domain region is a region having a plurality of portions divided and distributed in the matrix region, the domain region has a structure in which a first layer composed of a first Al.sub.x1Ti.sub.(1-x1) compound and a second layer composed of a second Al.sub.x2Ti.sub.(1-x2) compound are layered on each other, the matrix region has a structure in which a third layer composed of a third Al.sub.x3Ti.sub.(1-x3) compound and a fourth layer composed of a fourth Al.sub.x4Ti.sub.(1-x4) compound are layered on each other.

A surface-coated cutting tool includes a substrate and a coating film that coats the substrate, wherein the coating film includes a hard coating layer constituted of a domain region and a matrix region, the domain region is a region having a plurality of portions divided and distributed in the matrix region, the domain region has a structure in which a first layer composed of a first Al.sub.x1Ti.sub.(1-x1) compound and a second layer composed of a second Al.sub.x2Ti.sub.(1-x2) compound are layered on each other, the matrix region has a structure in which a third layer composed of a third Al.sub.x3Ti.sub.(1-x3) compound and a fourth layer composed of a fourth Al.sub.x4Ti.sub.(1-x4) compound are layered on each other.

A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, wherein: the coating layer comprises at least one α-type aluminum oxide layer; and, in the α-type aluminum oxide layer, a texture coefficient TC (0,0,12) of a (0,0,12) plane is from 4.0 or more to 8.4 or less, and a texture coefficient TC (0,1,8) of a (0,1,8) plane is from 0.5 or more to 3.0 or less.

A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate, wherein: the coating layer comprises at least one α-type aluminum oxide layer; and, in the α-type aluminum oxide layer, a texture coefficient TC (0,0,12) of a (0,0,12) plane is from 4.0 or more to 8.4 or less, and a texture coefficient TC (0,1,8) of a (0,1,8) plane is from 0.5 or more to 3.0 or less.

The cutting insert may include a substrate including a first surface, a second surface, and a cutting edge. The substrate may include a hard phase and a binder phase, and the hard phase may include a first hard phase and a second hard phase. In X-ray diffraction analysis, a peak of the first hard phase may be observed on a higher angle side than a peak of the second hard phase. The second hard phase in the second surface may include a compressive residual stress of 150 MPa or more. A maximum height (Rz) in the second surface may be 0.2 to 1.5 μm. A maximum height of the cutting edge may be 2 to 30 times the maximum height in the second surface.

A surface-coated cutting tool includes a substrate and a coating film that coats the substrate, wherein the coating film includes a hard coating layer constituted of a domain region and a matrix region, the domain region is a region having a plurality of portions divided and distributed in the matrix region, the domain region has a structure in which a first layer composed of a first Al.sub.x1Ti.sub.(1-x1) compound and a second layer composed of a second Al.sub.x2Ti.sub.(1-x2) compound are layered on each other, the matrix region has a structure in which a third layer composed of a third Al.sub.x3Ti.sub.(1-x3) compound and a fourth layer composed of a fourth Al.sub.x4Ti.sub.(1-x4) compound are layered on each other, the first AlTi compound and the third AlTi compound have a hexagonal crystal structure, the second AlTi compound and the fourth AlTi compound have a cubic crystal structure.

A surface-coated cutting tool includes a substrate and a coating film that coats the substrate, wherein the coating film includes a hard coating layer constituted of a domain region and a matrix region, the domain region is a region having a plurality of portions divided and distributed in the matrix region, the domain region has a structure in which a first layer composed of a first Al.sub.x1Ti.sub.(1-x1) compound and a second layer composed of a second Al.sub.x2Ti.sub.(1-x2) compound are layered on each other, the matrix region has a structure in which a third layer composed of a third Al.sub.x3Ti.sub.(1-x3) compound and a fourth layer composed of a fourth Al.sub.x4Ti.sub.(1-x4) compound are layered on each other, the first AlTi compound and the third AlTi compound have a hexagonal crystal structure, the second AlTi compound and the fourth AlTi compound have a cubic crystal structure.

A coated tool of the present disclosure may include a base and a coating layer covering at least a part of the base. The base may include a hard phase of a carbonitride including Ti and a binder phase including at least one of Co and Ni and has a thermal expansion coefficient at 25 to 1000° C. of 9.0×10.sup.−6/° C. or more. The coating layer may include a TiCN layer and an Al.sub.2O.sub.3 layer positioned on the TiCN layer. The TiCN layer may have a compressive stress of 250 to 500 MPa. The Al.sub.2O.sub.3 layer may have a thickness of 2 μm or more and a compressive stress of 450 MPa or more, and the value of the compressive stress is greater than the compressive stress of the TiCN layer.

A coated tool of the present disclosure may include a base and a coating layer covering at least a part of the base. The base may include a hard phase of a carbonitride including Ti and a binder phase including at least one of Co and Ni and has a thermal expansion coefficient at 25 to 1000° C. of 9.0×10.sup.−6/° C. or more. The coating layer may include a TiCN layer and an Al.sub.2O.sub.3 layer positioned on the TiCN layer. The TiCN layer may have a compressive stress of 250 to 500 MPa. The Al.sub.2O.sub.3 layer may have a thickness of 2 μm or more and a compressive stress of 450 MPa or more, and the value of the compressive stress is greater than the compressive stress of the TiCN layer.