Abstract: A sintered hard metal body having improved heat resistance and higher cutting performance is produced by a process including mixing together at least one hard substance, at least one binder material, and at least one of at least one complex carbide and at least one complex nitride to form a starting mixture each constituent of which is in powdered form. The at least one hard substance is selected from the group consisting of carbides, nitrides, and carbonitrides of transition metals of Groups IVB, VB and VIB of the Periodic Table of Elements, is present as at least one of a carbide, a mixed carbide, a nitride, a mixed nitride, a carbonitride, and a mixed carbonitride, and has a cubic crystal form. The at least one binder metal is selected from the group including iron, nickel and cobalt.

Abstract: A apex seal is formed by cold pressing and sintering a mixture of Clevite and tungsten carbide powders to form a seal wherein harder rounded carbide particles are distributed within a softer matrix.

Abstract: A method is disclosed for producing a Wc-Co-Cr alloy which comprises alloying a mixture consisting essentially of in percent by weight of from about 85 to about 90 tungsten carbide, wherein the particle size of the tungsten carbide is less than about 1 micrometer in diameter, from about 9 to about 11 cobalt metal powder, wherein the particle size of the cobalt is from about 1 to about 5 micrometers in diameter, and from about 3.5 to about 4.5 chromium wherein the chromium is provided as chromium carbide to produce a Wc-Co-Cr alloy the alloy capable of being used as a coating wherein the hardness of the coating is from about 1060 to about 1240 DPH carbide hardness and from about 870 to about 980 DPH matrix hardness and wherein the roughness is from about 190 to about 200 AA.

Abstract: Cobalt-bound tungsten carbide metal matrix composites having a unique microstructure are produced by consolidating partially sintered greenware under high pressures, e.g., 120,000 psi, at temperatures less than those used for conventional liquid phase sintering in a relatively short time, e.g., from less than one minute to less than about one hour. The composites have a binder phase which contains less than about 80 weight percent of the tungsten found in a composite prepared from the same or similar compositions via liquid phase sintering. These composites provide cutting tools with both toughness and wear resistance which exceed that of cutting tools made from the same or similar compositions via liquid phase sintering.

Abstract: The mould of this invention is intended for the manufacture of small dimensioned parts, in particular those dimensioned on the order of 0.1 mm or less. It comprises one or several mould shells each of which is obtained by:machining a matrix (100) from a hard material of which at least a portion (104) will have the form of a negative of the desired shell, such portion having dimensions slightly greater than those of the shell to be finally obtained;positioning the matrix within a cavity (106) and obtaining a blank of the shell (116) by injecting a mixture composed of a metallic powder and a binding agent into the cavity;eliminating the binding agent by heating the blank and thereafter subjecting said blank to a sintering operation.

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 coated cemented carbide alloy having jointly a high toughness and high wear resistance is produced by specifying the cooling rate during sintering in efficient manner, which alloy comprises a cemented carbide substrate consisting of a hard phase of at least one member selected from the group consisting of carbides, nitrides and carbonitrides of Group IVa, Va and VIa 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 thereon, consisting of at least one member selected from the group consisting of carbides, nitrides, oxides and borides of Group IVa, Va and VIa metals of Periodic Table, solid solutions thereof and aluminum oxide, in which the hardness of the cemented carbide substrate in the range of 2 to 5 .mu.m from the interface between the coating layer and substrate is 800 to 1300 kg/mm.sup.

Abstract: This case relates to tough, wear resistant graded structure composites, to a process for preparing the same and to tools and products fabricated therefrom. The composites have a surface layer e.g. of WC and a binder, an interface layer, e.g. which is a stepwise transition from the surface layer whereby the binder content thereof gradually increases, a substrate layer which is a combination of e.g. an initial high carbon steel layer and finally a base layer of bainitic steel. The composites are substantially non-porous and can be used to fabricate components such as drill bits, wear plates, pump components machine tools, seals, washers, bearings and the like.

Abstract: A sintered compact is obtained by sintering a mixture containing about 50 to 75 percent by volume of cubic boron nitride and about 25 to 50 percent of a binder under cBN-stable superhigh pressure conditions. The binder contains about 20 to 50 percent by weight of Al and one or more Ti compounds selected from the group consisting of TiN.sub.z, Ti(C,N).sub.z, TiC.sub.2, (Ti,M)C.sub.z, (Ti,M) (C,N).sub.z and (Ti,M)N.sub.z, wherein M indicates a transition metal of the group IVa, Va or VIa of the periodic table excepting Ti, and wherein z is within a range of 0.5.ltoreq.z.ltoreq.0.85. The atomic ratio of the content of Ti to that of the transition metal M in the binder is within the range of about2/1.ltoreq.Ti/M.ltoreq.97/3.The binder further contains tungsten or one or more tungsten compounds, whereby the total tungsten concentration in the binder is about 4 to 40 percent by weight.

Abstract: A process of hot pressing of materials to form articles or compacts is characterized by the steps: (A) providing a compactable particulate mixture; (B) uniaxially pressing the particles without heating to provide article or compact (22); (C) placing at least one article or compact (22) in an open pan (31) having an insertable frame (32) with edge surfaces (34) that are not significantly pressure deformable, where the inside side surfaces of the frame are parallel to the central axis B--B of the open pan, and where each article or compact is surrounded by fine particles of a separating material; (D) evacuating air from the container and sealing the articles or compacts inside the container by means of top lid (36); (E) hot pressing the compacts at a pressure from 352.5 kg/cm.sup.2 to 3,172 kg/cm.sup.

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 IIIb, IVa, 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: A method is provided for producing an erosion-resistant layer or coating on the surface of a metallic workpiece. The method includes providing a thermally sprayable alloy of Ni-Cr-Fe-B-Si and thermally spraying the alloy on the workpiece to a specified thickness, following which the sprayed-on layer is heated in vacuum to a temperature between 250.degree. C. to 400.degree. C. for a time at the stated temperature of about 5 to 30 minutes sufficient to effect degassing of the layer. The temperature of the layer is thereafter raised to a range of about 800.degree. C. to 950.degree. C. and maintained at that temperature in vacuum for between 5 to 30 minutes. The temperature at the layer is then raised to between 900.degree. C. and 1100.degree. C. under a protctive atmoshpere at a pressure of between 200 to 600 mm Hg to effect fursion of the layer at above its melting point, following which the coated metallic workpiece is finally cooled to room temperature under the protective atmosphere.

Abstract: A cobalt bonded tungsten carbide powder is produced by a method comprising preparing a mixture consisting of a first tungsten carbide powder having a particle size of -5 microns, a second tungsten carbide powder having a particle size of -44+10 microns, a cobalt powder having a particle size of -5 microns and a carbon powder having a particle size of -1 micron. The mixture has proportions, by weight totaling 100%, of about 10% to 30% first tungsten carbide, 40% to 80% second tungsten carbide, 8% to 25% cobalt and 0.5 to 3% carbon. The mixture is processed by compacting, sintering, crushing, and classifying to produce the cobalt bonded tungsten powder in a size range -100+10 microns.

Abstract: A method for manufacturing a metal boride ceramic material, includes mixing metal boride powder with 1-20 wt. % metal powder and 0.1-10 wt. % carbon powder, shaping the mixture and firing it. Alternatively, the metal boride powder may be mixed with 0.1-89 wt. % metal carbide powder thereby make a mixture, followed by shaping the mixture and firing it.

Abstract: An alloy tool of hard metal has a working part and a non-working part. The working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase and an iron family metal as a basis metal of the binder phase. The working part includes a region for working a work piece. The non-working part is made of a hard metal containing carbide of at least a metal selected from a group of elements belonging to the groups IVa, Va and VIa of the periodic table as a basis metal of the hard phase of the non-working part and of an iron family metal as a basis metal of the binder phase of the non-working part. A diffused junction between the working and non-working parts bonds the two parts together.

Abstract: A compacted, single phase or multiphase composite article. Particles for use in the compacted article are produced by providing a precursor compound containing at least one or at least two metals and a coordinating ligand. The compound is heated to remove the coordinating ligand therefrom and increase the surface area thereof. It may then be reacted so that at least one metal forms a metal-containing compound. The particles may be consolidated to form a compacted article, and for this purpose may be used in combination with graphite or diamonds. The metal-containing compound may be a nonmetallic compound including carbides, nitrides and carbonitrides of a refractory metal, such as tungsten. Th metal-containing compound may be dispersed in a metal matrix, such as iron, nickel or cobalt.

Abstract: The present invention relates to a sintered body for chip forming machining containing at least one hard constituent comprising a carbide, nitride and/or carbonitride of a metal of group IVB, VB or VIB in the periodical system and a binder metal based upon Co, No and/or Fe, in which the body comprises a core containing eta-phase or an intermediate phase, substantially free of carbon and/or nitrogen surrounded by a hard constituent- and binder phase-containing surface zone, free of said eta-phase or intermediate phase.

Abstract: The present invention relates to a cemented carbide body, preferably for rock drilling, mineral cutting and wear parts, in which the content of binder phase in the surface is lower and in the center higher than the nominal content. In the center there is a zone having a uniform content of binder phase. The WC grain size is uniform throughout the body.

Abstract: A process of hot isostatic pressing of powders to form electrical contacts is characterized by the steps: (A) mixing powders, 1 in the Drawing, from metal containing powder or metal containing powder plus carbon powder, where at least one of Ag and Cu is present, (B) thermal cleaning treatment of the powder, 2 in the Drawing, (C) granulating the thermally treated powder, 3 in the Drawing, (D) uniaxially pressing the powders without heating, 5 in the Drawing, to provide a compact, (E) placing at least one compact in a pressure-transmitting, pressure-deformable container, 6 in the Drawing, and surrounding each compact with fine particles of a separating material, (F) evacuating air from the container, 7 in the Drawing, (G) sealing the compacts inside the container, 8 in the Drawing, (H) hot isostatic pressing, 9 in the Drawing, the compacts through the pressure transmitting material at a pressure from 352 kg/cm.sup.2 to 2,115 kg/cm.sup.2 and a temperature from 0.5.degree. C. to 100.degree. C.

Abstract: A sintered metal part which has a pressed and sintered core; the part is coated with a sintered metal surface layer; the layer has a property different from that of the metal part; the interior regions of the core are free of the metal constituting the coating; and process for making the parts.

Abstract: A method of manufacturing by a powder metallurgy process a rotary drill bit including a bit body having a plurality of cutting elements mounted on the outer surface thereof comprises the steps of forming a hollow mould for moulding at least a portion of the bit body, packing the mould with powdered matrix material, and infiltrating the material with a metal alloy in a furnace to form a matrix. Before packing the mould with powdered matrix material, there are postioned in spaced locations on the interior surface of the mould a plurality of cutting element, each of which is formed of a material, such as a polycrystalline diamond material, which is thermally stable at the temperature necessary to form the matrix. Also positioned in the mould, adjacent the rearward side of each cutting element, is a support material such that, at least after formation of the matrix, the support material has a higher modulus of elasticity than the matrix.

Abstract: Amorphous metal-ceramic and microcrystalline metal-ceramic composites are synthesized by solid state reaction-formation methods. These metal-ceramic composites are characterized by a composition that ranges from about 75 to about 99.9 percent ceramic in about 0.1 to about 25 percent amorphous or microcrystalline metal binder phase.

Abstract: Sputter targets and a process for producing sputter targets are provided, comprised of carbides and/or nitrides and/or borides of refractory metals. In a first step, a dense composite body is produced comprised of one or more carbides and/or nitrides and/or borides of the metals of Groups IV A-VI A of the periodic table and a metallic binding agent comprised of one or more metals of the iron group of the periodic table. This composite body in the form of a shaped blank is machined, if necessary, and the binding agent is removed by chemical or electrochemical treatment. The sputter target as so produced has excellent mechanical strength and high thermal shock resistance. Levels of contaminating elements and the residual metallic binding agent are extremely low, meeting the requirements typically placed on sputter targets.

Abstract: A blend of tungsten carbide powder and cemented tungsten carbide cobalt chips is loaded into a cavity surrounding a steel bearing blank and infiltrated with a copper base infiltrant to create a chip matrix bearing surface.

Abstract: Method for the production of a wear resistant part of a soil working tool comprising forming a mixture of 67-90% by volume of iron particles consisting of at least 97% Fe and 10-33% by volume of hard particles having a desired particle size distribution, and subsequently pressing the mixture at a pressure of at least 3500 kp/cm.sup.2 to form a compact, sintering the compact at a temperature of 900.degree.-1200.degree. C., and optionally sinter forging the sintered compact. The sintered part consists of an iron matrix in which hard particles with a predetermined particle size distribution are embedded.

Abstract: A cBN sintered compact for an end mill obtained by sintering mixed powder prepared by mixing about 35 to 50 percent by volume of cubic boron nitride powder smaller than about 2 .mu.m in average particle size with about 50 to 65 percent by volume of a binder under cBN-stable superhigh pressure conditions. The binder contains about 20 to 30 percent by weight of Al and one or more Ti compounds selected from a group of TiN.sub.z, Ti(C,N).sub.z, TiC.sub.z, (Ti,M)C.sub.z, (Ti,M) (C,N).sub.z and (Ti,M)N.sub.z (where M indicates a transition metal element of the group IVa, Va or VIa of the periodic table excepting Ti and z is within a range of about 0.7.ltoreq.z.ltoreq. about 0.

Abstract: A method is disclosed for manufacturing a reaction sintered composite article which comprises at least one ceramic component. The method comprises preparing a particulate mixture of precursor powders leading to the formation of said composite material upon reaction sintering, pressing said particulate mixture to a self-sustaining body, heating said body up to a temperature below the temperature at which the reaction sintering is initiated, comminuting the heat treating body, selecting particles of a suitable grain size distribution, pressing said particles into shapes of desired size and configuration, and heating said shapes up to a temperature at which the reaction sintering is initiated. The reaction sintered body comprises borides, carbides, nitrides or silicides of a transition metal of the groups IVb, Vb or VIb of the periodic table (comprising titanium, hafnium, zirconium, vanadium, niobium, tantalum, chromium, molybdenum and tungsten), and a metal oxide.

Abstract: An electrical contact comprises 5 to 20 weight percent tungsten carbide, 0.5 to 3 weight percent graphite, balance silver. The contact has low erosion rate, low contact resistance, and anti-welding properties.

Abstract: A sintered tungsten carbide material and method for manufacturing same in which the method includes the steps of combining metal particles composed of from 75 to 95 percent by weight of a composition containing at least 70 percent by weight of tungsten carbide and from 5 to 25 percent by weight of a binder metal composition, the binder metal composition consisting essentially of from 5 to 15 percent by weight of chromium and from 85 to 95 percent by weight of nickel; pressing the metal particles into a pressed body; sintering the pressed body in a sintering chamber for a period ranging from 20 to 200 minutes, at a temperature ranging from 1400.degree. to 1500.degree. C., and in a protective atmosphere which is one of a vacuum, a noble gas, a mixture of noble gases, and hydrogen gas to form a sintered body; and treating the sintered body for a period ranging from 20 to 200 minutes, at a temperature ranging from 1300.degree. to 1400.degree. C.

Abstract: A diamond sintered body for tools contains a diamond content in excess of 93 percent and not more than 99 percent by volume and a residue including at least one of a metal or a carbide selected from groups IVa, Va and VIa of the periodic table and an iron group metal of 0.1 to 3 percent by volume in total and pores at least 0.5 percent and not more than 7 percent by volume.

Abstract: Amorphous boron-carbon alloy cutting tool bits and methods of making them are described. The tool bits can be composites of conventional hard alloys containing the amorphous boron carbon alloy in a first layer over a conventional hard alloy layer such as cobalt bonded tungsten carbide. The amorphous boron carbon alloy used is preferably produced in bulk with a grain size less than 30 .ANG. and ground into a powder. The tool bits are produced by cold compressing, in a tool bit die, the lower layer material at about 2000 psi followed by hot compressing the composite containing the added amorphous boron carbon alloy powder at about 1350.degree.-1500.degree. C. The resultant cutting tool bit has a cutting lifetime at least four times that of conventional carbide cutting tool bits even when cutting such things as nickel superalloys at speeds in excess of 125 surface feet per minute (SFM).

Abstract: A method of manufacturing by a powder metallurgy process a rotary drill bit including a bit body having a plurality of cutting elements mounted on the outer surface thereof comprises the steps of forming a hollow mould for moulding at least a portion of the bit body, packing the mould with powdered matrix material, and infiltrating the material with a metal alloy in a furnace to form a matrix. Before packing the mould with powdered matrix material, there are positioned in spaced locations on the interior surface of the mould a plurality of cutting elements, each of which is formed of a material, such as a polycrystalline diamond material, which is thermally stable at the temperature necessary to form the matrix. Also positioned in the mould, adjacent the rearward side of each cutting element, is a support material such that, at least after formation of the matrix, the support material has a higher modulus of elasticity than the matrix.

Abstract: An electrical contact formed of a mixture of finely divided electrically conductive metal doped with graphite or cadmium oxide. A thin coating of the electrically conductive metal is disposed upon the side of the contact which is adapted to be welded or brazed to an electrically conductive support. The electrical contact is made by mixing the finely divided cadmium oxide and pressing the mixture into a desired shape. A slurry of conductive metal is then sprayed on one side of the contact. After coating, the contact is sintered at a temperature less than the melting point of the electrically conductive material, whereby the contact is formed and the coating is firmly attached to it. The invention is particularly useful with silver or copper-based electrical contacts.

Abstract: A solid particle erosion resistant coating includes angular titanium carbide particles uniformly dispersed through a high chromium iron matrix. In one form, the aggregate comprises, by weight, about 30-50% TiC, about 10-30% Cr, about 1.5-5% C and the balance essentially iron in the form of ferrite. The matrix also includes metallurgically identifiable amounts of high chromium content M.sub.7 C.sub.3 carbides therethrough. The coating does not exhibit austenitic or martensitic structure therehthough. A powder alloy consolidated body also includes a surface adjacent region having a similar TiC and high chromium iron matrix. Further, a method for obtaining the coating includes heating above the austenitization temperature of the matrix alloy and below the melting temperature of iron, and cooling the aggregate so as to attain iron in the form of ferrite in the matrix.

Abstract: A method is disclosed for applying hard tungsten carbide particles to the surface of metal stabilizers used in the drilling of oil, gas, geothermal and water wells. The process consists of applying a soft, elastic metal powder to the surface of the substrate. Large tungsten carbide particles, which have also been coated with the soft powder, are placed on top of the layer of soft powder. The particles are then covered with additional soft powder, which powder is then fused to form a homogeneous, large tungsten carbide particle containing mixture bonded to the substrate. A hard matrix is applied and fused over the large tungsten carbide particle containing mixture. The large tungsten carbide particles, which have a low coefficient of expansion, are thereby contained in a soft elastic metal matrix which acts as an expansion and cushion material, while the hard matrix presents a less resilient, more wear resistant surface.

Abstract: A method for manufacturing a metal sintered body disclosed herein is characterized by the use of steps of: mixing 70 to 90 weight % of self-fluxing alloy powder and 10 to 30 weight % of metal powder of high melting point having a higher melting point than that of the self-soluble metal powder and in which the self-fluxing alloy powder is liable to be deposited thereon to obtain a metal powder having a sintering property; using a material in which 1 to 10 weight % of plastic binder is kneaded with the metal powder having a sintering property to obtain a molded body having a predetermined shape; and sintering the molded body at a temperature in excess of a liquid phase line of the self-fluxing alloy powder.

Abstract: Disclosed is a method for preparing a sintered body containing cubic boron nitride which comprise the steps ofcontacting a starting material containing boron nitride and/or a starting material containing at least one selected from the group consisting of metals of groups IVa, Va and VIa of the periodic table, silicon, aluminum, iron group metals and compounds of the aforesaid metals with at least one selected from the group consisting of borazine, a borazine derivative and a compound composed of boron, nitrogen and hydrogen as will release hydrogen by a thermal decomposition under pressure to form boron nitride; andsintering the material under conditions of a predetermined pressure and temperature under which cubic boron nitride is kept stable. Also disclosed is a method for preparing cubic boron nitride which comprises, in addition to the above steps, recovering cubic boron nitride from the obtained sintered body by a chemical and/or physical manner.

Abstract: Replaceable nozzles may be provided in a tungsten carbide drill bit manufactured by powder metallurgical infiltration techniques wherein at least one nozzle is threaded into a corresponding molded threaded bore in the bit. Despite the practical nonmachinability and brittleness of the tungsten carbide material, secure threaded insertion can be achieved if a squared thread design is used, and if the mold plug for forming the threaded bore is oversized to take into account the average variation in shrinkage in a bit formed by powder metallurgical infiltration techniques.

Abstract: A powder metallurgy composite material comprising grains of a relatively hard material and a binder for binding the grains together, the binder being metastable and transformable at ambient temperature by the application of mechanical force from an initial state in which the major phase of the binder is austentic to a second state in which the major phase of the binder is martensitic, whereby the binder, while undergoing this transformation, absorbs mechanical energy applied to the composite material for increasing its fracture toughness and resistance to fatigue crack nucleation and propagation. Also disclosed is a method of heat-treating the composite materials to improve their transformation-toughening characteristics. A heat-treatable composite material having such improved transformation-toughening properties is also disclosed.

Abstract: A process improvement is disclosed for making diamond wire die compacts of the type which are generally described as an inner polycrystalline diamond mass surrounded by and bonded to a mass of metal bonded carbide, such as cobalt cemented tungsten carbide. It is known to make these dies by high pressure-high temperature processes, typical conditions being 50 kbar and temperatures in excess of 1300.degree. C. The improvement comprises disposing within the reaction sub-assembly (e.g. metal carbide and diamond within a zirconium cup) a set of discs of specific materials in specified arrangements. For example, on one side of the mass of metal carbide and diamond is disposed one disc of a diamond catalyst/solvent and one disc of a refractory metal such as molybdenum, and on the other side are disposed at least two discs of one or more transition metals such as zirconium. These discs are generally placed inside the sub-assembly cup.

Abstract: A hard alloy including at least one hard phase and a binary or multicomponent binder metal alloy, in which the hard substance comprises a finely dispersed, homogeneous distribution in the binder metal. The hard phase comprises a carbide of a Group IVb, Vb or VIb transition metal, and the binder metal alloy comprises a solid alloy of a Group IVb, Vb or VIb transition metal, with Re, Ru, Rh, Pd, Os, Ir, or Pt.

Abstract: An improved heat exchanger for high energy laser mirrors is provided which comprises one or more sections each hot pressed into a desired configuration to define coolant passageways, and subsequently stacked and joined by a suitable means such as diffusion bonding. A surface of one of the sections may either support a laser mirror faceplate or be finished to provide the desired laser mirror surface.

Abstract: A uniform, large size tungsten powder having properties which make it suitable for producing large size tungsten carbide powder is produced by doping a tungsten oxide starting powder with a lithium compound prior to reduction

Abstract: A method is disclosed for forming roller cutters and also for forming cutting teeth for rolling cutter bits, including cutter inserts, cutter teeth formed in place, or formed separately and welded in place, etc., by powder metallurgy as a densified powder metallurgical composite of at least two varying phases, the composite having a substantially continuous mechanical property gradient therethrough. The gradient is from one region having hardness or wear resistant properties to another region having toughness properties. The method comprises:providing a first powder mixture comprising a major proportion by volume of a powdered refractory compound and a minor proportion by volume of a powdered binder metal or alloy. Providing a second powder comprising a powdered binder metal or alloy or a mixture comprising a powdered refractory material and a powdered binder metal or alloy, present in a lesser proportion by volume than in the first powder.

Abstract: There is presented an electrical contact material consisting of an alloy of gold and a compound selected from a group consisting of a carbide, a boride, or a silicide of a refractory element. The compound of the refractory element is selected from a group consisting of WC, Hfb.sub.2, TiB.sub.2, ZrB.sub.2, WSi.sub.2, and TiSi.sub.2. The resulting alloys have a hexagonal crystal structure and exhibit high wear resistance, low contact resistance, low electrical noise, and a homogeneous uncontaminated microstructure.