Abstract: A method is disclosed for controlling a self-propagating reaction in a particulate medium. The method comprises controlling the boundary heat flux of the reaction to produce reaction waves which travel through the particulate medium undergoing a self-propagating reaction. The method provides a product having a unitary, solid structure with layers of alternating density. Preferably the reaction is a reaction between two metals to produce an intermetallic compound or between a metal and a non-metal to produce a ceramic compound. Nickel aluminide is a preferred intermetallic compound. Also disclosed is a controlled reactive sintering process for producing a finely divided intermetallic compound comprising comminuting the layered body of intermetallic compound.

Abstract: A sintered titanium-based carbonitride alloy contains hard constituents based on, in addition to Ti, W and/or Mo, one or more of the metals Zr, Hf, V, Nb, Ta or Cr in 5-30% binder phase based on Cobalt and/or nickel. The content of tungsten and/or molybdenum, preferably molybdenum in the binder phase is >1.5 times higher than in the rim and >3.5 times higher than in the core of adjacent hard constituent grains. The alloy is produced by a particular method.

Abstract: There is now provided a method of manufacturing a sintered body of titanium-based carbonitride alloy comprising hard constituents in 5-25% binder phase where the hard constituents contain, in addition to Ti, one or more of the metals V, Nb, Ta, Cr, Mo or W and the binder phase is based on cobalt and/or nickel by powder metallurgical methods, i.e., milling, pressing and sintering. The composition of the hard constituents is:0.88<a<0.96;0.04<b<0.08;0.ltoreq.c<0.04;0.ltoreq.d<0.04;0.60<f<0.73;0.80<x<0.90; and0.31<h<0.40.and the overall composition of the hard constituents phase is expressed by the formula:(Ti.sub.a,Ta.sub.b,Nb.sub.c,V.sub.d).sub.x (Mo.sub.e,W.sub.f).sub.y (C.sub.g,N.sub.h).sub.z.

Abstract: Transition metal carbonitrides (in particular, titanium carbonitride, TiC.sub.0.5 N.sub.0.5) are synthesized by a self-propagating reaction between the metal (e.g., titanium) and carbon in a nitrogen atmosphere. Complete conversion to the carbonitride phase is achieved with the addition of TiN as diluent and with a nitrogen pressure .gtoreq.0.6 MPa. Thermodynamic phase-stability calculations and experimental characterizations of quenched samples provided revealed that the mechanism of formation of the carbonitride is a two-step process. The first step involves the formation of the nonstoichiometric carbide, TiC.sub.0.5, and is followed by the formation of the product by the incorporation of nitrogen in the defect-structure carbide.

Abstract: An Ni-based bearing alloy consisting, by weight, of 9-30% Cr, 5-19% Fe, 0.1-1.5% Si, 2-22% Co, 1.4-11.0% Mo, and the balance Ni and incidental impurities, said alloy having a matrix in which hard particles of a Co-Mo-Cr-Si alloy and/or BN are uniformly dispersed in weight ratios of 5 to 35% and not more than 5.0, respectively. The Ni-based alloy matrix provides superior heat resistance. Hard particles of Co-Mo-Cr-Si alloy uniformly dispersed in the matrix improve sliding characteristic with or without uniform dispersion of Bn as a solid lubricant, whereby the bearing alloy exhibits superior heat resistance and sliding characteristic when used in high temperature oxidizing atmosphere.

Abstract: Magnetic material of the Sm-Fe-N system exhibits a crystalline hard magnetic phase with a Th.sub.2 Zn.sub.17 crystalline structure wherein N atoms are incorporated in the crystalline lattice. A preliminary product having a dual component Sm.sub.2 Fe.sub.17 phase is produced by mechanical alloying followed by thermal treatment to achieve the desired microstructure. The preliminary product is heated in a nitrous atmosphere, as a result of which, the hard magnetic phase is formed. The preliminary product may also be obtained by a rapid-quenching technique.

Abstract: A coated cemented carbide alloy, excellent in toughness as well as wear resistance and which is used for cutting tools and wear resistance tools is provided herein. This coated cemented carbide alloy is composed of a cemented carbide substrate consisting of a hard phase of at least one member selected from carbides, nitrides and carbonitrides of the Group IVb, Vb and VIb metals of Periodic Table and a binder phase consisting of at least one member selected from the iron group metals, and a monolayer or multilayer provided on the substrate consisting of at least one member selected from the carbides, nitrides, oxides and borides of Group IVb, Vb and VIb metals of Periodic Table, solid solutions thereof and aluminum oxide, and wherein a binder phase-enriched layer is provided in a space 0.01 mm and 2 mm below the surface of the substrate with A-type and/or B-type pores inside the binder phase-enriched layer.

Abstract: Infiltrate a porous, self-reinforced .beta.-Si.sub.3 N.sub.4 preform with a metal or a crystallizable glass to yield a composite material. The preform possesses a low glass phase and has a density of from about 50 to about 70 percent of theoretical density. Prepare the .beta.-Si.sub.3 N.sub.4 preform by subjecting a porous body formed from an .alpha.-Si.sub.3 N.sub.4 powder composition to two sequential heat treatments. The first heat treatment occurs below the .alpha.- to .beta.- conversion temperature and results in a strengthened body that can be machined. The second heat treatment occurs above that temperature and yields the self-reinforced .beta.-Si.sub.3 N.sub.4 preform. Conventional infiltration procedures with an infiltrant that is a metal or a glass results in a Si.sub.3 N.sub.4 /metal or Si.sub.3 N.sub.4 /glass composite material that has 50 to 70 percent of its volume occupied by .beta.-Si.sub.3 N.sub.4 whiskers.

Abstract: This invention relates to a process for producing a rare earth-containing powder comprising crushing a rare earth-containing alloy in water, drying the crushed alloy material at a temperature below the phase transformation temperature of the material, and treating the crushed alloy material with a passivating gas at a temperature from the ambient temperature to a temperature below the phase transformation temperature of the material. Rare earth-containing alloys suitable for use in producing magnets utilizing the powder metallurgy technique, such as Nd-Fe-B and Sm-Co alloys, can be used. The passivating gas can be nitrogen, carbon dioxide or a combination of nitrogen and carbon dioxide. If nitrogen is used as the passivating gas, the resultant powder has a nitrogen surface concentration of from about 0.4 to about 26.8 atomic percent. Moreover, if carbon dioxide is used as the passivating gas, the resultant powder has a carbon surface concentration of from about 0.02 to about 15 atomic percent.

Abstract: The invention relates to the reprocessing of used evaporation boats. This is done by a method which comprises comminuting used, aluminum-contaminated evaporation boats and roasting them in a nitrogen-containing atmosphere.

Abstract: A sintered metal part has a magnesium metasilicate mineral, or a magnesium metasilicate mineral and a magnesium orthosilicate mineral, or at least one of a magnesium metasilicate mineral and a magnesium orthosilicate mineral and at least one of boron nitride and manganese sulfide dispersed throughout the metal matrix. An iron-based sintered sliding member is of a structure that free graphite and an intercrystalline inclusion have been dispersed throughout the metal matrix that consists essentially of, in weight ratio, 1.5 to 4% of carbon, 1 to 5% of copper, 0.1 to 2% of tin, 0.1 to 0.5% of phosphorus, 0.

Abstract: A pressure-reaction synthesis process for producing increased stiffness and improved strength-to-weight ratio titanium metal matrix composite materials comprising exothermically reacting a titanium powder or titanium powder alloys with non-metal powders or gas selected from the group consisting of C, B, N, BN, B.sub.4 C, SiC and Si.sub.3 N.sub.4 at temperatures from about 900.degree. to about 1300.degree. C., for about 5 to about 30 minutes in a forming die under pressures of from about 1000 to 5000 psi.

Abstract: This invention relates to a process for producing a rare earth-containing powder comprising crushing a rare earth-containing alloy in a passivating gas at a temperature from ambient temperature to a temperature below the phase transformation temperature of the material.Additionally, this invention relates to a process for producing a rare earth-containing powder compact comprising crushing a rare earth-containing alloy in water, compacting the crushed alloy material, drying the compacted alloy material at a temperature below the phase transformation temperature of the material, and treating the compacted alloy material with a passivating gas at a temperature from ambient temperature to a temperature below the phase transformation temperature of the material.Rare earth-containing alloys suitable for use in producing magnets utilizing the powder metallurgy technique, such as Nd-Fe-B and Sm-Co alloys, can be used.

Abstract: Self-supporting bodies are produced by reactive infiltration of a parent metal into a boron donor material and a carbon donor material. The reactive infiltration typically results in a composite comprising a boron-containing compound, a carbon-containing compound and residual metal, if desired. The mass to be infiltrated may contain one or more inert fillers admixed with the boron donor material and carbon donor material. The relative amounts of reactants and process conditions may be altered or controlled to yield a body containing a wide ranging varying volume percentage of ceramic, metal, and porosity.

Abstract: A permanent magnet essentially consisting of in weight percent, 60% to 68% at least one transition element by weight, 30% to 38% at least one rare earth element by weight, 0.1% to 1.5% nitrogen by weight, and 0.8% to 1.5% boron by weight is disclosed. A method for producing the permanent magnet containing at least one rear element, at least one rare earth element, nitrogen and boron includes melting, cooling, milling, magnetizing, and compacting the transition element, the rare earth element and boron to form a green compact, and then sintering the green compact in nitrogen atmosphere having a constant partial pressure for 1 to several hours to form the permanent magnet.

Abstract: The present invention relates to parts, such as a drive gear and driven gear, for use in a rotary gear pump exhibiting good sliding characteristics against a pump case made of light metals such as aluminum alloys. These parts are obtained by subjecting aluminum alloy powders, which have been solidified at a cooling rate of 100.degree. C./sec or more, or aluminum alloy powders having particle diameters of 350 .mu.m or less, to powder compacting and hot extrusion and optionally further to hot forging, or subjecting the aluminum alloy powders to powder forging.

Abstract: A process for reaction injection molding of ceramic articles is disclosed. The process comprises (a) injecting a fluid, non-dilatant mixture comprising a ceramic powder, a metal powder or mixtures thereof, and a curable ceramic precursor that is a liquid below its curing temperature, into a heated mold, (b) curing the ceramic precursor to produce a hardened molded article, (c) heating the hardened molded article under a suitable atmosphere to a temperature sufficient to convert the ceramic precursor to a ceramic, and (d) sintering the ceramic to the desired density.

Abstract: A composite material is provided which includes a discrete phase including grains made of a first substance; and a continuous phase including a thin coating film made of a second substance and formed on the surface of each of the grains. The thin coating film has a mean thickness smaller than the mean particle size of the grains. The grains are separated substantially from each other by the thin coating film. The porosity of the composite material is 5% or less.

Abstract: The invention relates to a composite hard metal body of hard material, a binder and embedded reinforcing material, as well as to a process for the production of the composite hard metal body by methods of powder metallurgy.In order to create a composite hard metal body with improved toughness under load, improved hardness and a lower fracture susceptibility, the invention proposes to build in monocrystalline, preferably needle-shaped and/or platelet-shaped reinforcing materials, coated with an inert layer with respect to the binder metal phase and consisting of borides and/or carbides, and/or nitrides and/or carbonitrides of the elements of Groups IVa or Va or mixtures thereof and/or coated monocrystalline reinforcing material of SiC, Si.sub.3 N.sub.4, Si.sub.2 N.sub.2 O, Al.sub.2 O.sub.3, ZrO.sub.2, AlN and/or BN.

Abstract: The present invention is a method for densifying powder metallurgical parts to 100% theoretical density. The method comprises applying a high pressure of 0.1-100 MPa during sintering in a high pressure furnace at a temperature before which the liquid phase is formed and maintaining this pressure during the rest of the sintering cycle until the furnace has cooled to almost room temperature. The method achieves rapid, complete closure of the porosity which results in parts with close dimensional tolerances and practically no warpage.

Abstract: A cermet alloy having a structure comprising a hard phase and a bonding phase, said hard phase comprising (1) at least one of MC, MN and MCN, wherein M is at least one element selected from Ti, Zr, Hf, Th, V, Nb, Ta, Pa, Cr, Mo, U and W and (2) at least one W-Co-B compound; said bonding phase comprising Co. The cermet has superior toughness and hardness, and can be worked by conventional sintering methods. The invention also includes a method for producing the cermet.

Abstract: Disclosed are a high toughness cermet comprising a sintered alloy comprising 75 to 95% by weight of a hard phase of carbide, nitride or carbonitride containing Ti, at least one of W, Mo and Cr, and N and C, and the balance of a binder phase composed mainly of an iron group metal, and inevitable impurities,wherein the content of Ti in said sintered alloy is 35 to 85% by weight calculated on TiN or TiN and TiC, and the contents of W, Mo and Cr are 10 to 40% by weight in total calculated on WC, Mo.sub.2 C and/or Cr.sub.3 C.sub.2,the relative concentration of said binder phase at the 0.01 mm-inner portion from the surface of said sintered alloy is 5 to 50% of the average binder phase concentration of the inner portion, and the relative concentration of said binder phase at the 0.1 mm-inner portion from the surface of said sintered alloy is 70 to 100% of the average binder phase concentration of the inner portion, anda compression stress of 30 kgf/mm.sup.

Abstract: A silicon nitride sintered body having a high strength at high temperatures as well as at room temperature can be provided by the method of the present invention, which includes preparing a raw material consisting of SI.sub.3 N.sub.4 powder, a rare earth element oxide powder, and SiC powder, and at least one of a W compound powder and a Mo compound powder, forming the raw material into a shaped body, and then firing the shaped body in N.sub.2 atmosphere to substantially crystallize the grain boundary phase of the Si.sub.3 N.sub.4 grains. The silicon nitride sintered body includes Si.sub.3 N.sub.4 as a main component, and the remainder of a rare earth element compound, SiC and at least one of a W compound and a Mo compound, the grain boundary phase of Sio.sub.3 N.sub.4 grains consisting substantially of crystal phases. The silicon nitride sintered body is dense and thin in color so that uneven coloring thereof can be decreased.

Abstract: Magnet material of the Sm-Fe-N system having a crystalline, hard magentic phase with a Th.sub.2 Zn.sub.17 crystal structure, wherein N atoms are incorporated into the crystal lattice, is produced. First a preliminary product is formed by sintering a Sm-Fe powder which is oriented in a magnetic field to provide a sintered body having a two-component Sm-Fe phase. The sintered body is heat treated in a nitrogen atmosphere to form the Sm-Fe-N hard magnetic phase. The nitrogen atomosphere may advantageously be reactive nitrogen.

Abstract: According to the present invention there is now provided a method of making a sintered titanium-based carbonitride alloy. According to the method, melt-metallurgical raw materials containing the metallic alloying elements for hard constituent-forming as well as binder phase-forming elements are melted and cast, using no intentional additions of the elements C, N, B and O, to form a pre-alloy which in solidified condition of brittle intermetallic phases with hard constituent-forming and binder phase-forming elements mixed in atomic scale. The pre-alloy is crushed and/or milled to powder with grain size <50 .mu.m. The powder is carbonitrided for simultaneous formation in situ of extremely fine-grained <0.1 .mu.m, hard constituent particles enclosed in their binder phase.

Abstract: A shaped body of anisotropic magnetic material based on the Sm-Fe-N system which has a crystalline, hard magnetic phase with a Th.sub.2 Zn.sub.17 crystal structure, wherein N atoms are incorporated in the crystal lattice, is produced by compacting a powder Sm-Fe preliminary product with an Sm-Fe phase having a magnetically isotropic structure, followed by hot-shaping to provide an intermediate product with a Sm-Fe phase having a magnetically anisotropic structure, followed by heat treating the intermediate product in a nitrogen atmosphere to provide a Sm-Fe-N hard magnetic phase.

Abstract: This invention relates to a process for producing a rare earth-containing material capable of being formed into a permanent magnet comprising crushing a rare earth-containing alloy and treating the alloy with a passivating gas at a temperature below the phase transformation temperature of the alloy. This invention further relates to a process for producing a rare earth-containing powder comprising crushing a rare earth-containing alloy in a passivating gas at a temperature from ambient temperature to a temperature below the phase transformation temperature of the material. This invention also relates to a process for producing a rare earth-containing powder comprising crushing a rare earth-containing alloy in water, drying the crushed alloy material at a temperature below the phase transformation temperature of the material, and treating the crushed alloy material with a passivating gas at a temperature from the ambient temperature to a temperature below the phase transformation temperature of the material.

Abstract: This invention relates to a process for producing a rare earth-containing powder comprising crushing a rare earth-containing alloy in water, drying the crushed alloy material at a temperature below the phase transformation temperature of the material, and treating the crushed alloy material with a passivating gas at a temperature from the ambient temperature to a temperature below the phase transformation temperature of the material. Rare earth-containing alloys suitable for use in producing magnets utilizing the powder metallurgy technique, such as Nd-Fe-B and Sm-Co alloys, can be used. The passivating gas can be nitrogen, carbon dioxide or a combination of nitrogen and carbon dioxide. If nitrogen is used as the passivating gas, the resultant powder has a nitrogen surface concentration of from about 0.4 to about 26.8 atomic percent. Moreover, if carbon dioxide is used as the passivating gas, the resultant powder has a carbon surface concentration of from about 0.02 to about 15 atomic percent.

Abstract: A process for producing high-strength, substantially nonporous alloys by means of a three-component mixture, including admixing a first component of one or more low-melting temperature metals or alloys thereof, a second component of one or more high-melting temperature metals or alloys thereof, and a substantially inert third component of one or more refractory compounds, subjecting the mixture to changes in temperature so as to form a mixture capable of being shaped at a temperature well below the melting or decomposition temperature of the highest melting metal and the inert refractory compound.

Abstract: A cutting insert of a sintered carbonitride alloy and with a complicated geometry, the insert having improved efficiency. This is obtained by giving the powder non-uniform compaction during pressing of the powder into a press-body so that the ultimate working edges will have a higher relative density than the surrounding, more "supporting" material in the press-body. By these means are often obtained surface defects in the form of cracks because of dissolved strains during the sintering.

Abstract: A copper alloy composite material which comprises a copper alloy matrix and at least one additive selected from solid materials having self-lubricity and wear-resistant materials and uniformly dispersed in the alloy matrix is described. The composite material has improved wear resistance and anti-seizing properties.

Abstract: Metal and ceramic particles of various morphologies are clad with a coating from the transition metal group consisting of silver, gold, copper, nickel, iron, cobalt, aluminum etc., or combinations thereof, to provide improved coated particles for microelectronics or metal matrix composites or other uses. Refractory metal precursor core particles, such as tungsten, molybdenum, niobium and zirconium, as examples, are provided from a composite of tungsten and copper, for example, made by pressurizing and infiltrating or liquid phase sintering of molten copper into a porous tungsten skeleton. Precursor chip particles derived from a tungsten impregnated billet are used as starter particles which may be further enhanced by cogrinding in an attritor ball mill with smaller copper particles to thereby produce an enhanced copper clad-coating of tungsten particles with predetermined percent by weight of copper and tungsten content.

Abstract: A method for the fabrication of a superplastic composite material having metallic aluminum reinforced with silicon nitride includes thoroughly mixing silicon nitride with metallic aluminum, pressure-sintering the resultant mixture, further heating and pressing the sintered mixture, hot extrusion-molding the resultant sintered article, subjecting the molded article, when necessary, to a heat treatment such as the T6 treatment thereby forming a superplastic composite material, and deforming the composite material in a temperature region in which the material exhibits superplasticity.

Abstract: A method for manufacturing a dense cermet article including about 80-95% by volume of a granular hard phase and about 5-20% by volume of a metal binder phase. The hard phase is (a) the hard refractory carbides, nitrides, carbonitrides, oxycarbides, oxynitrides, carboxynitrides, borides, and mixtures thereof of the elements selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, and B, or (b) the hard refractory carbides, nitrides, carbonitrides, oxycarbides, oxynitrides, and carboxynitrides, and mixtures thereof of a cubic solid solution of Zr--Ti, Hf--Ti, Hf--Zr, V--Ti, Nb--Ti, Ta--Ti, Mo--Ti, W--Ti, W--Hf, W--Nb, or W--Ta. The binder phase is a combination of Ni and Al having a Ni:Al weight ratio of from about 85:15 to about 88:12, and 0-5% by weight of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Co, B, and/or C. The method involves presintering the hard phase/binder phase mixture in a vacuum or inert atmosphere at about 1475.degree.-1675.degree. C., then HIPing at about 1575.degree.-1675.degree. C.

Abstract: A method for the production of a metallic powder molding material is disclosed which comprises a step of imparting mechanical energy due to at least one of such physical actions as vibration, pulverization, attrition, rolling, shocks, agitation, and mixing a metallic particles in a vessel whose interior is held under vacuumized atmosphere or an atmosphere of inert gas thereby enabling the metallic particles to contact each other and acquire improvement in surface quality and a step of hot molding the metallic particles thereby producing a molding material.

Abstract: Process for the powder-metallurgical production of work pieces, particularly tools, containing high-melting point carbides and/or carbonitrides homogeneously distributed in a matrix, in which an amount of elements of the IVa and Va groups, or secondary groups, of the periodic table is adjusted to at least 3 weight percent of the alloy, a low carbon and/or nitrogen concentration is established, and primary precipitates are prevented; and a desired carbon and/or nitrogen content is created by atomization of the melt into powder vaporizing medium.

Abstract: A hobbing tool made of cermet composed of 70 to 97 percent by weight of hard phase and a binder phase. The hard phase is made of a composite carbonitride of transition metals including titanium and tungsten, and at least one other element. The binder phase contains nickel and/or cobalt and inevitable impurities. The ratio between nitride atoms and carbon atoms and the ratio between titanium atoms and the atoms of transition metals other than titanium in the hard phase should be within specific ranges. The cermet having the above composition has an increased toughness and an excellent resistance to heat and wear and is difficult to weld.

Abstract: An improved ceramic-metal composite comprising a mixture of a ceramic material with a ductile intermetallic alloy, preferably Ni.sub.3 Al.

Abstract: A dispersion strengthened copper alloy containing a copper matrix, and dispersion particles dispersed in the copper matrix within a range of 0.5 to 6 vol %. In this alloy, an average diameter of a matrix region where the dispersion particles are not present is 0.3 .mu.m or less, and the total amount of solid solution elements contained in the copper matrix is determined such that, when this amount of the solid solution elements is added to pure copper, the electric conductivity of the matrix is lowered by 5% IACS or less.

Abstract: A surface refined sintered alloy with a burnt surface, comprising 75 to 95% by weight of a hard phase containing Ti, C and N as the essential components and otherwise comprising at least one of Zr, Hf, V, Nb, Ta, Cr, Mo and W and the balance of the alloy comprising a binder phase composed mainly of Co and/or Ni and inevitable impurities, wherein the sintered alloy satisfies at least two conditions selected from the group consisting of the following (1) to (3):(1) the average grain size of the hard phase in a surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.8 to 1.2-fold of the average grain size of the hard phase in the inner portion of the sintered alloy excluding the surface layer;(2) the average content of the binder phase in the surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.7 to 1.

Abstract: The proposed invention is used for the manufacture from the obtained composite of cutting tools, hard alloy tooling, dies and other products. A method according to the invention involves preparing a mixture, compacting it, placing the mixture into a synthesis zone, igniting the mixture, with subsequent reaction of components of the mixture under combustion conditions. Then cure is carried out during a period ranging from about 0.1 seconds to about 0.5 hours, and the hot combustion products are compacted under pressure at an average pressure rise rate ranging from about 10 to about 2000 kgf/cm.sup.2.s, with subsequent cure of the compacted product under isobaric conditions to complete homogenization of the composite, with subsequent cooling thereof to obtain an end composite.

Abstract: There are disclosed a high strength nitrogen-containing cermet which comprises 7 to 20% by weight of a binder phase composed mainly of Co and/or Ni, with the balance being a hard phase composed mainly of TiC, TiN and/or Ti(C,N) and inevitable impurities, wherein the hard phase comprises 35 to 59% by weight of Ti, 9 to 29% by weight of W, 0.4 to 3.5% by weight of Mo, 4 to 24% by weight of at least one of Ta, Nb, V and Zr, 5.5 to 9.5% by weight of N and 4.5 to 12% by weight of C; and a process for preparing the same which comprises via the formulating, mixing, drying, molding and sintering steps of Co and/or Ni powder, at least one powder of TiC, Ti(C,N) and TiN, WC powder, Mo and/or Mo.sub.2 C, and at least one powder of carbides of Ta, Nb, V and Zr, wherein the sintering step is carried out by elevating the temperature up to 1350.degree. C. in vacuum, with the nitrogen atmosphere being made 1 torr at 1350.degree. C.

Abstract: A superplastic composite material is produced by thoroughly and homogeneously mixing particles or whiskers of silicon nitride and aluminum metal powder in a solvent, then removing the solvent from the resultant mixture, sintering the residual mixture at an elevated temperature, further compressing it at an elevated temperature, then hot extrusion-molding the compressed mixture thereby forming a shaped article, and heat-treating this shaped article.

Abstract: The present invention relates to a method of preparing an alloy for use as a cutting tool material comprising hard principles and binder phase by which a uniform distribution of the hard principles in the binder phase is obtained, and the resulting product.

Abstract: The invention relates to sintered hard metals having high cutting properties, particularly plastic deformation resistance at high temperatures, crater resistance and the like, suitable for use as cutting tools, wear resistant tools and materials for dies, and the method for producing the same. The invention has for an object to obtain both sintered hard metals having the aforesaid high properties by sintering metallic components comprising IVa group metals, VIa group metals or metals of both groups substituted by Va group metals up to 60 mol % respectively, a B-1 type solid solution hard phase consisting of non-metallic components of C, N and O, and a metallic bonding phase, in a CO gas atmosphere, and to sintered hard metals in which an uniform hardness is imparted to the surface and interior thereof by the method of sintering the said sintered hard metal in a CO gas atmosphere.

Abstract: A method for manufacturing a sintered body is provided, comprising the steps of dispersing powdery silicon nitride and a sintering assistant into a first dispersion medium composed mainly of substance capable of being extracted by supercritical fluid to form a first slurry and casting the first slurry to form a compact; dispersing powdery material into a second medium composed mainly of substance capable of being extracted by the supercritical fluid to form a second slurry and coating the second slurry on the surface of the compact to form a film layer; dipping the compact covered with the film layer in the supercritical fluid to extract the first dispersion medium and the second dispersion medium, respectively from the compact and the film layer; heating the compact from which the first and second dispersion mediums have been removed to form the film layer into a film layer impermeable to gas; and sintering the compact covered with the film layer impermeable.

Abstract: The present invention relates to a method of sintering ceramics and ceramics obtained by said method. According to the present invention, the synthesis and sintering of ceramics can be simultaneously carried out by utilizing the reaction heat generated when at least one metallic element selected from metallic elements of IIb, IVb, Vb and VIb groups of the Periodic Table is combined with at least one nonmetallic element such as B, C N and Si without heat or by preliminarily heating the ceramics at temperatures remarkably lower than the usual sintering temperature ceramics thus-produced are superior in abrasion resistance and corrosion resistance.

Abstract: There are disclosed a surface sintered alloy with a burnt surface, comprising 75 to 95% by weight of a hard phase containing Ti, C and N as the essential components and otherwise comprising at least one of Zr, Hf, V, Nb, Ta, Cr, Mo and W and the balance of the alloy comprising a binder phase composed mainly of Co and/or Ni and inevitable impurities, wherein the sintered alloy satisfies at least one condition selected from the group consisting of the following (1) to (3):(1) the average grain size of the hard phase in a surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.8 to 1.2-fold of the average grain size of the hard phase in the inner portion of the sintered alloy excluding the surface layer;(2) the average content of the binder phase in the surface layer to the inner portion of 0.05 mm from the burnt surface of the sintered alloy is 0.7 to 1.

Abstract: Substantially dense, void-free ceramic-metal composites are prepared from components characterized by chemical incompatibility and non-wetting behavior. The composites have a final chemistry similar to the starting chemistry and microstructures characterized by ceramic grains similar in size to the starting powder and the presence of metal phase. A method for producing the composites requires forming a homogeneous mixture of ceramic-metal, heating the mixture to a temperature that approximates but is below the temperature at which the metal begins to flow and presssing the mixture at such pressure that compaction and densification of the mixture occurs and an induced temperature spike occurs that exceeds the flowing temperature of the metal such that the mixture is further compacted and densified. The temperature spike and duration thereof remains below that at which significant reaction between metal and ceramic occurs. The method requires pressure of 60-250 kpsi employed at a rate of 5-250 kpsi/second.

Abstract: This invention provides a cermet alloy improved in toughness high-temperature strength and chipping resistance. This cermet alloy consists essentially of 50-95% by weight of a hard phase of a composite carbo-nitride of at least both of W and Ti and, optionally, one or more elements selected from the group consisting of Groups 4a, 5a and 6a elements of the periodic table, the balance being a binding phase, of an Fe family element or elements and inevitable impurities, said composite carbo-nitride has a rim-and-core structure which comprises a core portion of a composite carbo-nitride poor in Ti and nitrogen, surrounded thereon by a rim portion of a composite carbo-nitride rich in Ti and nitrogen. It is preferred that the hard phase consists of 50% by volume or less of TiN or TiCN particles having N.gtoreq.C and forming no rim-and-core structure and the composite carbo-nitride having the rim-and-core structure.