A cutting tool comprises a substrate and an AlTiN layer, the AlTiN layer including cubic Al.sub.xTi.sub.(1-x)N crystal grains, an atomic ratio x of Al in the Al.sub.xTi.sub.(1-x)N being 0.7 or more and 0.95 or less, the AlTiN layer including a first major surface on a side of a surface of the cutting tool and a second major surface on a side of the substrate, the AlTiN layer including a first region having a distance of 0 nm or more and 100 nm or less from the first major surface, and a second region having a distance of more than 100 nm and 150 nm or less from the first major surface, the first region having a maximum oxygen content ratio of 5 atomic % or more and 30 atomic % or less, the second region having a maximum oxygen content ratio of less than 5 atomic %.

A surface coated cutting tool comprises a base material and a coating layer that coats the base material, the coating layer including an alternate layer composed of a first unit layer and a second unit layer alternately stacked, the first unit layer being composed of a nitride containing aluminum and zirconium, in the first unit layer, when the total number of metal atoms constituting the first unit layer is represented as 1, a ratio thereto of the number of atoms of the zirconium being not less than 0.65 and not more than 0.95, the second unit layer being composed of a nitride containing titanium and silicon, in the second unit layer, when the total number of metal atoms constituting the second unit layer is represented as 1, a ratio thereto of the number of atoms of the silicon being larger than 0 and not more than 0.20.

Cemented carbide contains a first hard phase and a binder phase. The first hard phase is composed of tungsten carbide particles. The binder phase is composed of cobalt, nickel, iron, and copper as constituent elements. An average content of each of the constituent elements is not lower than 10 atomic % and not higher than 30 atomic %. Cemented carbide contains no second hard phase, or a content of the second hard phase is equal to or lower than 2 mass % of a total amount of cemented carbide. The second hard phase is composed of a compound containing at least one type of a metal element selected from the group consisting of a group-IV element, a group-V element, and a group-VI element in a periodic table except for tungsten and at least one type of an element selected from the group consisting of carbon, nitrogen, and oxygen.

A cutting tool comprises a substrate and a coating layer provided on the substrate, the coating layer including a multilayer structure layer composed of a first unit layer and a second unit layer, and a lone layer, the lone layer including cubic Ti.sub.zAl.sub.1-zN crystal grains, an atomic ratio z of Ti in the Ti.sub.zAl.sub.1-zN being 0.55 or more and 0.7 or less, the lone layer having a thickness with an average value of 2.5 nm or more and 10 nm or less, the multilayer structure layer having a thickness with an average value of 40 nm or more and 95 nm or less, one multilayer structure layer and one lone layer forming a repetitive unit having a thickness with an average value of 50 nm to 100 nm, a maximum value of 90 nm to 110 nm, and a minimum value of 40 nm to 60 nm.

A coated cutting tool including a substrate and a coating is provided. The coating includes a nano-multilayer of alternating layers of a first nanolayer being Ti.sub.1-xAl.sub.xN, 0.35≤x≤0.70, and a second nanolayer being Ti.sub.1-yAl.sub.yN, 0.12≤y≤0.25. A sequence of one first nanolayer and one second nanolayer forms a layer period. The average layer period thickness in the nano-multilayer is ≤7 nm. The nanomultilayer has a columnar structure with an average column width of ≤70 nm.

Improved thin film coatings, cutting tool materials and processes for cutting tool applications are disclosed. A boron-doped graded diamond thin film for forming a highly adhesive surface coating on a cemented carbide (WC—Co) cutting tool material is provided. The thin film is fabricated in a HFCVD reactor. It is made of a bottom layer of BMCD in contact with a surface layer of the cemented carbide, a top layer made of NCD and a transition layer with a decreasing concentration gradient of boron obtained by changing the reaction conditions through ramp up option in hot filament CVD reactor. The top layer has a low friction coefficient. The bottom layer in the coating substrate interface has better interfacial adhesion through cobalt and boron reactivity and decreased cobalt diffusivity in the diamond. The transition layer has minimized lattice mismatch and sharp stress concentration between the top and bottom layers.

A method of forming a polycrystalline diamond body includes mixing a sintering agent with diamond powder to form a premixed layer, the sintering agent including at least one alkaline earth metal carbonate; forming an infiltration layer adjacent to the premixed layer, the infiltration layer including an infiltrant material including at least one alkaline earth metal carbonate; and subjecting the premixed layer and the infiltration layer to high pressure high temperature conditions.

A surface-coated cutting tool comprises a hard coat layer including a complex nitride layer on the tool substrate. The complex nitride layer has a composition: (Me.sub.1−x−yAl.sub.xM.sub.y)N.sub.z where Me is Ti or Cr, x≤0.80, 0.00≤y≤0.20, 0.20≤(1−x−y)≤0.65, and 0.90≤z≤1.10 (where x, y, and z represents atomic ratios, M is at least one element selected from the group consisting of Groups 4 to 6 elements, Y, Si, La, and Ce in the IUPAC periodic table). The hard coat layer has an interfacial region extending from a point above the surface of the tool substrate and having a thickness in a range of 5 to 100 nm, and the N content to the total of Me, Al, M, and N contents is 10 to 30 atomic % at the point and increases toward the surface of the cutting tool.

A cBN-based ultra-high pressure sintered body contains cBN particles and a binder phase. The binder phase contains at least one of a nitride or oxide of Al or a nitride, carbide, or carbonitride of Ti, and a metal boride having an average particle diameter of 20 to 300 nm is dispersed in an amount of 0.1 to 5.0 vol % in the binder phase. The metal boride includes a metal boride (B) containing at least one of Nb, Ta, Cr, Mo, and W as a metal component and containing no Ti and a metal boride (A) containing only Ti as a metal component. In a case where a ratio (vol %) of the metal boride (A) in the metal boride is represented by V.sub.a and a ratio (vol %) of the metal boride (B) is represented by V.sub.b, a ratio of V.sub.b/V.sub.a is 0.1 to 1.0.

Provided is a coated cutting tool, which includes a hard coating film containing a layer (b) formed of a nitride or a carbonitride, a layer (c) which is a layered coating film formed by alternately layering a nitride or carbonitride layer (c1) that contains 55 atom % or more and 75 atom % or less of Al, Cr having a second highest content percentage, and at least Si and a nitride or carbonitride layer (c2) that contains 55 atom % or more and 75 atom % or less of Al and Ti having a second highest content percentage, each layer having a film thickness of 50 nm or less, and a layer (d) that is a nitride or carbonitride that contains, with respect to a total amount of metal elements (including metalloid elements), 55 atom % or more and 75 atom % or less of Al, Cr having a second highest content percentage.