SURFACE COATED CUTTING TOOL

To provide a surface coated cutting tool having high hardness and high toughness.SOLUTION: In the surface coated cutting tool, a coating layer has an average thickness of 1.0-20.0 μm, whose average composition is represented by the formula :TiaX1bX2c)(CdNe)(X1 and X2 are different from each other and are any of V, Nb and Ta):0.05≤a/(a+b+c)≤0.60 0.05≤b/(a+b+c)≤0.60 0.05≤c/(a+b+c)≤0.60 0.20≤d/(d+e)≤0.80 0.20≤e/(d+e)≤0.80 Sconfig=-R/2{[a/(a+b+c)]ln[a/(a+b+c)]+[b/(a+b+c)]ln[b/(a+b+c)]+[c/(a+b+c)]ln[c/(a+b+c)]+[d/(d+e)]ln[d/(d+e)]+[e/(d+e)]ln[e/(d+e)]}≥0.75R (R is gas constant and ln is natural logarithm), and includes crystal grain having NaCl-type face-centered cubic structure.SELECTED DRAWING: Figure 2 【課題】高硬度かつ高靱性の表面被覆切削工具の提供。【解決手段】被覆層は、平均厚さが１．０～２０．０μｍで、式：（ＴｉａＸ１ｂＸ２ｃ）（ＣｄＮｅ）（Ｘ１、Ｘ２は異なり、それぞれ、Ｖ、Ｎｂ、Ｔａのいずれか）で表したとき、０．０５≦ａ／（ａ＋ｂ＋ｃ）≦０．６００．０５≦ｂ／（ａ＋ｂ＋ｃ）≦０．６００．０５≦ｃ／（ａ＋ｂ＋ｃ）≦０．６００．２０≦ｄ／（ｄ＋ｅ）≦０．８００．２０≦ｅ／（ｄ＋ｅ）≦０．８０Ｓｃｏｎｆｉｇ＝－Ｒ／２｛［ａ／（ａ＋ｂ＋ｃ）］ｌｎ［ａ／（ａ＋ｂ＋ｃ）］＋［ｂ／（ａ＋ｂ＋ｃ）]ｌｎ［ｂ／（ａ＋ｂ＋ｃ）］＋［ｃ／（ａ＋ｂ＋ｃ）］ｌｎ［ｃ／（ａ＋ｂ＋ｃ）］＋［ｄ／（ｄ＋ｅ）］ｌｎ［ｄ／（ｄ＋ｅ）］＋［ｅ／（ｄ＋ｅ）］ｌｎ［ｅ／（ｄ＋ｅ）］｝≧０．７５Ｒ（Ｒは気体定数、ｌｎは自然対数）で、ＮａＣｌ型面心立方構造を有する結晶粒を含む表面被覆切削工具。【選択図】図２