Coated cutting tool

A coated cutting tool comprising a substrate and a coating layer formed on a surface of the substrate,

• the coating layer comprising a first laminate structure and a second laminate structure, wherein:
• the first laminate structure is a laminate structure in which compound layers of two kinds, each having a different composition, are laminated in an alternating manner, and the number of laminations is three or more;
• one compound layer of the compound layers of two kinds in the first laminate structure has a composition represented by formula (1) below:
• (AlaM1-a)N . . . (1)
• [wherein M denotes a metal element of at least one kind selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si, a denotes an atomic ratio of the Al element based on a total of the Al element and a metal element denoted by M, and a satisfies 0.58≤a≤0.80];
• the other compound layer of the compound layers of two kinds in the first laminate structure has a composition represented by formula (2) below:
• (AlbM1-b)N . . . (2)
• [wherein M denotes a metal element of at least one kind selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si, b denotes an atomic ratio of the Al element based on a total of the Al element and a metal element denoted by M, and b satisfies 0.57≤b≤0.79];
• the first laminate structure satisfies a condition represented by formula (A) below:
• 0<|Rx−Ry|<5 . . . (A)
• [wherein Rx denotes a ratio (unit:
• atom %) of a metal element of one kind relative to all the metal elements in the one compound layer, and Ry refers to a ratio (unit:
• atom %) of the metal element of one kind relative to all the metal elements in the other compound layer which is adjacent to the one compound layer, and the metal element of one kind denotes an element having the largest absolute value of a difference between a ratio relative to all the metal elements in the one compound layer and a ratio relative to all the metal elements in the other compound layer];
• the second laminate structure is a laminate structure in which compound layers of two kinds, each having a different composition, are laminated in an alternating manner, and the number of laminations is three or more;
• one compound layer of the compound layers of two kinds in the second laminate structure has a composition of at least one kind selected from the group consisting of a carbide, a nitride and a carbonitride of an element having a composition represented by formula (3) below:
• (Al1-c-dTicLd) . . . (3)
• [wherein L denotes a metal element of at least one kind selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si, c denotes an atomic ratio of the Ti element based on a total of the Al element, the Ti element and a metal element denoted by L, d denotes an atomic ratio of the metal element denoted by L based on a total of the Al element, the Ti element and the metal element denoted by L, and c and d respectively satisfy 0≤c≤1.00 and 0≤d≤0.50];
• the other compound layer of the compound layers of two kinds in the second laminate structure has a composition of at least one kind selected from the group consisting of a carbide, a nitride and a carbonitride of an element having a composition represented by formula (4) below:
• (Al1-e-fTieLf) . . . (4)
• [wherein L denotes a metal element of at least one kind selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W and Si, e denotes an atomic ratio of the Ti element based on a total of the Al element, the Ti element and a metal element denoted by L, f denotes an atomic ratio of the metal element denoted by L based on a total of the Al element, the Ti element and the metal element denoted by L, and e and f respectively satisfy 0≤e≤1.00 and 0≤f≤0.50];
• the second laminate structure satisfies a condition represented by formula (B) below:
• 5≤|Rz−Rw|. . . (B)
• [wherein Rz denotes a ratio (unit:
• atom %) of a metal element of one kind relative to all the metal elements in the one compound layer, and Rw refers to a ratio (unit:
• atom %) of the metal element of one kind relative to all the metal elements in the other compound layer which is adjacent to the one compound layer and the metal element of one kind denotes an element having the largest absolute value of a difference between a ratio relative to all the metal elements in the one compound layer and a ratio relative to all the metal elements in the other compound layer];
• an average thickness of each of the one compound layer and the other compound layer which constitute the first laminate structure and the one compound layer and the other compound layer which constitute the second laminate structure is from 1 nm or more to 300 nm or less;
• and
• an average thickness of the coating layer is from 1.5 μm or more to 15.0 μm or less.