Coated cutting tool

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

the coating layer includes an alternating laminate structure of an alternating laminate of:

a first composite nitride layer including a compound having a composition represented by formula (1) below:

(Ti x Al 1-x )N  (1)

(wherein x denotes an atomic ratio of the Ti element based on a total of the Ti element and the Al element and satisfies 0.10≤x≤0.35); and

a second composite nitride layer including a compound having a composition represented by formula (2) below:

(Ti y Al z M 1-y-z )N  (2)

(wherein: M denotes an element of at least one kind selected from the group consisting of Zr, Hf, V, Nb, Ta, Cr, Mo, W, Si and Y; y denotes an atomic ratio of the Ti element based on a total of the Ti element, the Al element and an element denoted by M; z denotes an atomic ratio of the Al element based on a total of the Ti element, the Al element and the element denoted by M; y satisfies 0.30≤y≤0.90; z satisfies 0.10≤z≤0.70; and y and z satisfy y+z≤1); and

the first composite nitride layer includes a phase having a lattice constant of from 0.400 nm or more to 0.430 nm or less and a phase having a lattice constant of from 0.755 nm or more to 0.810 nm or less.

2. The coated cutting tool according to claim 1 , wherein the first composite nitride layer includes a phase having a crystal system of a cubic crystal and a lattice constant of from 0.410 nm or more to 0.420 nm or less and a phase having a crystal system of a cubic crystal and a lattice constant of from 0.770 nm or more to 0.795 nm or less.

3. The coated cutting tool according to claim 1 , wherein the second composite nitride layer includes a phase having a crystal system of a cubic crystal and a lattice constant of from 0.400 nm or more to 0.430 nm or less.

4. The coated cutting tool according to claim 1 , wherein an average thickness T 1 of each of the layers of the first composite nitride layer is from 4 nm or more to 200 nm or less.

5. The coated cutting tool according to claim 1 , wherein an average thickness T 2 of each of the layers of the second composite nitride layer is from 4 nm or more to 200 nm or less.

6. The coated cutting tool according to claim 1 , wherein a ratio [T 1 /T 2 ] of an average thickness T 1 of each of the layers of the first composite nitride layer to an average thickness T 2 of each of the layers of the second composite nitride layer is from 0.10 or more to 1.30 or less.

7. The coated cutting tool according to claim 1 , wherein a ratio [T 1 /T 2 ] of an average thickness T 1 of each of the layers of the first composite nitride layer to an average thickness T 2 of each of the layers of the second composite nitride layer is from 0.10 or more to 0.90 or less.

8. The coated cutting tool according to claim 1 , wherein an average thickness of the alternating laminate structure is from 1.5 μm or more to 12.0 μm or less.

9. The coated cutting tool according to claim 1 , wherein:

the coating layer includes a lower layer between the substrate and the alternating laminate structure;

the lower layer is formed of a single layer or a laminate of a compound containing an element of at least one kind selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si and Y; and an element of at least one kind selected from the group consisting of C, N, O and B; and

an average thickness of the lower layer is from 0.1 μm or more to 3.5 μm or less.

10. The coated cutting tool according to claim 1 , wherein:

the coating layer includes an upper layer on a surface of the alternating laminate structure;

the upper layer is formed of a single layer or a laminate of a compound containing an element of at least one kind selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si and Y; and an element of at least one kind selected from the group consisting of C, N, O and B; and

an average thickness of the upper layer is from 0.1 μm or more to 3.5 μm or less.

11. The coated cutting tool according to claim 1 , wherein the entire coating layer has an average thickness of from 1.5 μm or more to 15.0 μm or less.

12. The coated cutting tool according to claim 1 , wherein the substrate is a cemented carbide, cermet, ceramic or a cubic boron nitride sintered body.

13. The coated cutting tool according to claim 2 , wherein the second composite nitride layer includes a phase having a crystal system of a cubic crystal and a lattice constant of from 0.400 nm or more to 0.430 nm or less.

14. The coated cutting tool according to claim 2 , wherein an average thickness T 1 of each of the layers of the first composite nitride layer is from 4 nm or more to 200 nm or less.

15. The coated cutting tool according to claim 3 , wherein an average thickness T 1 of each of the layers of the first composite nitride layer is from 4 nm or more to 200 nm or less.

16. The coated cutting tool according to claim 13 , wherein an average thickness T 1 of each of the layers of the first composite nitride layer is from 4 nm or more to 200 nm or less.

17. The coated cutting tool according to claim 2 , wherein an average thickness T 2 of each of the layers of the second composite nitride layer is from 4 nm or more to 200 nm or less.

18. The coated cutting tool according to claim 3 , wherein an average thickness T 2 of each of the layers of the second composite nitride layer is from 4 nm or more to 200 nm or less.

19. The coated cutting tool according to claim 4 , wherein an average thickness T 2 of each of the layers of the second composite nitride layer is from 4 nm or more to 200 nm or less.

20. The coated cutting tool according to claim 13 , wherein an average thickness T 2 of each of the layers of the second composite nitride layer is from 4 nm or more to 200 nm or less.