| 摘要 |
Provided is a surface-coated cutting tool which has a hard coating layer having excellent hardness and toughness, and which exhibits chipping resistance and fracture resistance over a long period of use. The hard coating layer contains at least a composite nitride or composite carbonitride layer represented by composition formula (Ti1-xAlx)(CyN1-y), and the content ratio x of Al and the content ratio y of C satisfy 0.60 ≤ x ≤ 0.95 and 0 ≤ y ≤ 0.005 (both x and y are atomic ratios). Some crystal grains constituting the composite nitride or composite carbonitride layer have a cubic structure, and some crystal grains constituting the composite nitride or composite carbonitride layer have a hexagonal structure. The area fraction occupied by the cubic crystal phase is 30-80% by area, and the crystal grains having a cubic structure have an average grain width (W) of 0.05-1.0 μm and an average aspect ratio (A) of 5 or less. Within the crystal grains having a cubic structure, the concentrations of Ti and Al have certain periodic changes. |
