A composite composed of one or a plurality of principal strengthening compounds and at least one principal cemented refractory metal that is prepared by combining a suitable binary to senary borides and/or carbides with a unitary to binary principal refractory metal is disclosed. As compared with the conventional sintered cemented carbides, the composite of the disclosure not only possess high hardness and high toughness but also has various ratios of principal components since it is not prepared with equal mole during the process.

In one aspect, methods of making freestanding metal matrix composite articles and alloy articles are described. A method of making a freestanding composite article described herein comprises disposing over a surface of the temporary substrate a layered assembly comprising a layer of infiltration metal or alloy and a hard particle layer formed of a flexible sheet comprising organic binder and the hard particles. The layered assembly is heated to infiltrate the hard particle layer with metal or alloy providing a metal matrix composite, and the metal matrix composite is separated from the temporary substrate. Further, a method of making a freestanding alloy article described herein comprises disposing over the surface of a temporary substrate a flexible sheet comprising organic binder and powder alloy and heating the sheet to provide a sintered alloy article. The sintered alloy article is then separated from the temporary substrate.

In one aspect, methods of making freestanding metal matrix composite articles and alloy articles are described. A method of making a freestanding composite article described herein comprises disposing over a surface of the temporary substrate a layered assembly comprising a layer of infiltration metal or alloy and a hard particle layer formed of a flexible sheet comprising organic binder and the hard particles. The layered assembly is heated to infiltrate the hard particle layer with metal or alloy providing a metal matrix composite, and the metal matrix composite is separated from the temporary substrate. Further, a method of making a freestanding alloy article described herein comprises disposing over the surface of a temporary substrate a flexible sheet comprising organic binder and powder alloy and heating the sheet to provide a sintered alloy article. The sintered alloy article is then separated from the temporary substrate.

A method for producing a cermet composition, including mixing a first predetermined amount of a yttria stabilized zirconia powder with between 2 and 8 weight percent mu-metal powder to define a homogeneous admixture, oxidizing the mu-metal in the admixture, forming the homogeneous admixture into a green body, calcining the green body in a first reducing atmosphere to remove oxygen from the oxidized mu-metal to yield a calcined body, and sintering the calcined body in a second reducing atmosphere to yield a densified body having no more than 0.8% porosity. The densified body has a plurality of mu-metal particles distributed therethrough, a hardness of at least 1450 HV, flexural strength of at least 200 kPSI, and a relative permeability μ/μ.sub.o of at least 850.

A cubic boron nitride sintered material includes: more than or equal to 85 volume % and less than 100 volume % of cubic boron nitride grains; and a remainder of a binder, wherein the binder includes WC, Co and an Al compound, and when a TEM-EDX is used to analyze an interface region including an interface at which the cubic boron nitride grains are adjacent to each other, oxygen exists on a whole or part of the interface, and a width D of a region in which the oxygen exists is more than or equal to 0.1 nm and less than or equal to 10 nm.

A cubic boron nitride sintered material includes: more than or equal to 85 volume % and less than 100 volume % of cubic boron nitride grains; and a remainder of a binder, wherein the binder includes WC, Co and an Al compound, and when a TEM-EDX is used to analyze an interface region including an interface at which the cubic boron nitride grains are adjacent to each other, oxygen exists on a whole or part of the interface, and a width D of a region in which the oxygen exists is more than or equal to 0.1 nm and less than or equal to 10 nm.

A sintered cemented carbide body including tungsten carbide, and a substantially cobalt-free binder including an iron-based alloy sintered with the tungsten carbide. The iron-based alloy is approximately 2-25% of the overall weight percentage of the sintered tungsten carbide and iron-based alloy. The tungsten carbide may be approximately 90 wt % and the iron-based alloy may be approximately 10 wt % of the overall weight percentage of the sintered tungsten carbide and iron-based alloy. The tungsten carbide may comprise a substantially same size before and after undergoing sintering. The iron-based alloy may be sintered with the tungsten carbide using a uniaxial hot pressing process, a spark plasma sintering process, or a pressureless sintering process. The sintered tungsten carbide and iron-based alloy has a hardness value of at least 15 GPa and a fracture toughness value of at least 11 MPa√m.

A sintered cemented carbide body including tungsten carbide, and a substantially cobalt-free binder including an iron-based alloy sintered with the tungsten carbide. The iron-based alloy is approximately 2-25% of the overall weight percentage of the sintered tungsten carbide and iron-based alloy. The tungsten carbide may be approximately 90 wt % and the iron-based alloy may be approximately 10 wt % of the overall weight percentage of the sintered tungsten carbide and iron-based alloy. The tungsten carbide may comprise a substantially same size before and after undergoing sintering. The iron-based alloy may be sintered with the tungsten carbide using a uniaxial hot pressing process, a spark plasma sintering process, or a pressureless sintering process. The sintered tungsten carbide and iron-based alloy has a hardness value of at least 15 GPa and a fracture toughness value of at least 11 MPa√m.

The cutting insert may include a substrate including a first surface, a second surface, and a cutting edge. The substrate may include a hard phase and a binder phase, and the hard phase may include a first hard phase and a second hard phase. In X-ray diffraction analysis, a peak of the first hard phase may be observed on a higher angle side than a peak of the second hard phase. The second hard phase in the second surface may include a compressive residual stress of 150 MPa or more. A maximum height (Rz) in the second surface may be 0.2 to 1.5 μm. A maximum height of the cutting edge may be 2 to 30 times the maximum height in the second surface.

The present invention provides a sintered body containing W and WC, having excellent hardness, strength, compactness, and corrosion resistance, without containing W.sub.2C, and capable of being used for the purpose of a cutting tool or a glass molding die, or a seal ring. There is provided a sintered body containing 4 to 50 vol % of tungsten metal as binder phases, 50 to 95 vol % of tungsten carbide (WC), and 0.5 to 5.0 vol % of tungsten oxide (WO.sub.2), in which the tungsten oxide (WO.sub.2) has an average grain size of 5 nm to 150 nm and is present in a sintered body structure at an average density of 5 to 20 particles/μm.sup.2.