Showing papers on "Powder metallurgy published in 1971"

Consolidated composite materials by powder metallurgy

Abstract: Directed to the powder metallurgy production of consolidated metal products wherein the starting material comprises dense wrought particles containing at least 15 percent by volume of a compressively deformable metal with the remainder being one or more other metals or non-metals with the internal structure of the particles being non-porous and with the constituents thereof being intimately united and interdispersed, ie, mechanically alloyed, said particles, upon consolidation, yielding metal or cermet products having unusual properties and capable of compositioinal characteristics not available as a result of other processing techniques

Porous metal structure

Abstract: An open-pore polyurethane structure containing powdered metal comprising coherent spherical particles separated by interconnected interstices and a method of producing this structure comprising mixing metal powder with the components to make a polyurethane structure in a container, polymerizing the mixture in place without stirring after onset of gelation. The polyurethane can be removed preferably by heating in air at a temperature below the sintering temperature for the metal, and the remaining metal can then be sintered forming a sintered porous metal or metal oxide structure depending on the metal used and sintering conditions. A number of porous nickel products were made by the process of the invention and after the removal of the polyurethane depending on the particle size of the nickel and the amount and conditions of sintering densities of the products ranged from 1 to 5 g./cc., compressive strengths from 100 to 20,000 and porosity from 20 to 80 percent. The porous metals or sintered porous metals can be used in mechanical support, air and liquid filters, porous bearings, porous electrodes, acoustic filters, impact absorbers, capillary wicks, void fillers, integral conductor-insulator rods, and three-dimensional highmodulus reinforcements.

Wrought dispersion strengthened metals by powder metallurgy

Abstract: THIS INVENTION RELATES TO THE POWDER METALLURGY OF WROUGHT, DISPERSION STRENGHTENED METALS AND ALSO TO A POWDER METALLURGY METHOD FOR PRODUCING WROUGHT DISPERSION STRENGTHNED METAL SHAPES SELECTED FROM THE GROUP CONSISTING OF NICKEL, COPPER, LOWER ALLOY STEELS, MARAGING STEELS, ZINC-BASE METALS, COLUMBIUM-BASE, TANTALUM-BASE AND TUNGSTEN-BASE REFRACTORY METALS, PLATINUMBASE METALS, AND GOLD-BASE METALS CHARACTERIZED METALLOGRAPHICALLY BY A UNIFORM DISTRIBUTION OF DISPERSOIDS IN BOTH THE LONGITUDINAL AND TRANSVERSE DIRECTIONS.

Method for making powder metallurgy shapes

Abstract: PRODUCTION OF POWDER METALLURGY SHAPES BY INTRODUCING A CHARGE OF POWDERED METAL TO BE COMPACTED TO A MOLD HAVING A CONFIGURATION CORRESPONDING GENERALLY TO THE DESIRED CONFIGURATION OF THE FINAL ARTICLE, PLACING THE MOLD IN A CONTAINER HAVING A SECONDARY PRESSURE MEDIA THEREIN AND SURROUNDING THE MOLD, HEATING THE ENTIRE ASSEMBLY TO AN ELEVATED TEMPERATURE FOR COMPACTING AND ISOTATICALLY COMPACTING THE POWDER BY THE APPLICATION OF FLUID PRESSURE WHITLE AT ELEVATE TEMPERAUTE.

Sintered austenitic-ferritic chromium-nickel steel alloy

Abstract: Powdered austenitic chromium-nickel stainless steel is blended with a powdered metal ferrite stabilizer, such as molybdenum, and the resulting blend is sintered to produce a new steel, namely, an unwrought austenitic-ferritic chromium-nickel alloy having, as sintered, desirably high tensile and yield strength and other desirable properties.

Powder-metallurgical products and the production thereof

Abstract: 1298944 Powder metallurgy INTERNATIONAL NICKEL Ltd 19 Aug 1970 [26 Aug 1969] 42490/69 Heading C7D Wrought homogeneous composite particles containing at least 15% volume of a compressively deformable metal made by dry impact milling according to Specification 1265343 are consolidated by compacting and sintering. Consolidation may be by hot or cold extrusion in a sealed compressible can, forging, rolling, pressing or hot pressing. The average spacing between the interdispersed constituents in the composite particle is <10 microns particle size being 20-200 microns and the consolidated product contains no more than 10% volume of segregated regions exceeding 25 microns in minimum dimension. A wide range of powder metallurgy products are made by the process and among these are alloys based on Pt, An, Pb, Zn, Al, Mg, Cu, Ni, Co, Fe, refractory metals. The "super" alloys Ni-Cr, Co-Cr, Fe-Cr with or without Mo, W, Nb, Ta, Al, Ti, Zr, Si, C, B; alloy steels, tool steels, moraging steels, stainless steels; B containing steels; limited solubility alloy systems such as Pb/Cu, Cu/Fe, Cu/W, Ag/W, Cu/Cr, Ag/Cr, Cu/Mo, Ag/Mo, Ag/Mn, Ag/Ni, Pt/An, Be/Mo, Ag/Pt; Ni-1%Li, Ni-B, Fe-SiŒ10%Ni; Rare earth permanent magnet compositions such as RCO 5 ; cemented carbides, borides and nitrides of Ti, Zr, Hf, Cr, W, Mo, V, Nb, Ta, SiC; oxides of Al, Be, R.E. Mg, Zn, Ti, Th and also cermets. The process is particularly suitable for the production of dispersion strengthened alloys which are strengthened with 0A05-25% volume of the oxides, carbides, nitrides or borides of Th, Y, Zr, Hf, Ti on the oxides of Si, Al, Ce, U, Mg, Ca, Be and rare earths. A large number of specific compositions are included.

Mechanism of the Oxidation of Titanium Disilicide

Abstract: Study of the oxidation of TiSi2 at temperatures of 300 to 1300 C. Wafers prepared using the techniques of powder metallurgy had densities of 95 to 98% of the theoretical value. On oxidation at temperatures up to 600 C, the polished wafers formed a protective, titania-silica glass. The rate data indicate a complex surface and diffusion-limited mechanism. Above 600 deg C, the oxide consisted of an amorphous SiO2 film with crystalline islands of TiO2 (rutile). From 1000 to 1300 C, parabolic kinetics with an activation energy of 21.3 kcal/mole were observed. These data are consistent with a model in which the rate-determining step is the diffusion of oxygen through the silica film with the simultaneous diffusion of titanium from the substrate to the islands of rutile growing on top of the amorphous silica.

PRELIMINARY STUDIES OF THE FABRICATION OF UAl4–Al TEST-PLATES BY POWDER-METALLURGICAL TECHNIQUES

Abstract: The preparation of UAl4 by induction melting and annealing (720°C, 993 K) yielded a product of restricted UAl4 content (81 wt.-%). The UAl4 phase has a variable stoichiometry (UAl4.0–UAl4.8), which leads to a slightly modified U–Al phase diagram. UAl4–Al dispersions can be prepared by powder-metallurgical techniques, resulting in structures with higher UAl4 content, improved phase-distribution rates, and specific particle sizes, compared with melting techniques. The thermal conductivity and thermal expansion of UAl4–Al dispersions have been measured over the whole concentration range. No technological difficulties, by comparison with UAl3-Al plate fabrication, were encountered. The production of UAl4-Al test plates (33 vol.-% UA14 ≃ 35 wt.-% U) is thus feasible on a laboratory scale. The work reported is the final stage in a series of studies of uranium aluminide-aluminium dispersion fuels obtained by powder routes.

Production of copper and copper oxide powder for powder metallurgy

Abstract: Copper base (including pure copper and copper alloy) or copper oxide powder is produced by atomizing a sulfurized copper base melt in the presence of oxygen to produce particles which are hollow as a result of sulfur dioxide formation therewithin, oxidizing the hollow particles in the presence of oxygen in order to cause weakening at the grain boundaries as a result of more sulfur dioxide formation therein, and crushing in order to make available the copper base particles. If desired, the oxidizing step, when carried for a longer time, results in oxidation of copper as well as sulfur and the crushing step results in copper oxide particles.

Creep of fine wires of powder metallurgical tungsten

Abstract: The creep behaviour of fine wires of pure powder metallurgical tungsten was studied over the temperature range 2100–3100°C. It was found that the steady-state creep rate is given by This result differs substantially from other reported work performed on specimens of larger diameter of polycrystalline pure tungsten. The difference is due to the fact that in the fine wire specimens numerous grain boundaries traverse the entire diameter. Creep can therefore take place by grain boundary sliding in these samples without the necessity of extensive grain deformation as is required for larger specimens where the grain size is much smaller than the sample diameter.

Application of powder metallurgy to an advanced-temperature nickel-base alloy, NASA-TRW 6-A

Abstract: Bar stock of the NASA-TRW 6-A alloy was made by prealloyed powder techniques and its properties evaluated over a range of temperatures. Room temperature ultimate tensile strength was 1894 MN/sq m (274 500 psi). The as-extruded powder product showed substantial improvements in strength over the cast alloy up to 649 C (1200 F) and superplasticity at 1093 C (2000 F). Both conventional and autoclave heat treatments were applied to the extruded powder product. The conventional heat treatment was effective in increasing rupture life at 649 and 704 C (1200 and 1300 F); the autoclave heat treatment, at 760 and 816 C (1400 and 1500 F).

Method of making alloy steel powder

Abstract: AN ALLOY STEEL POWDER TO BE USED FOR POWDER METALLURGY PROCESSES. THE POWDER IS PRODUCED BY ATOMIZING A MOLTEN STREAM OF ALLOY STEEL CONTAINING UP TO 0.40% BY WEIGHT OF CARBON AND CONTAINING ONE OR MORE OF THE FOLLOWING ELEMENTS: PERCENT NICKEL 0.20 TO 3.0 MOLYBDENUM 0.2 TO 1.0 CHROMIUM 0.2 TO 1.0 THE SILICON AND MANGANESE CONTENTS OF THE STEEL SHOULD BE LESS THAN 0.10% AND .50% BY WEIGHT RESPECTIVELY. FOLLOWING THE ATOMIZATION, THE RESULTANT PARTICLES ARE HEAT TREATED AT A TEMPERATURE OF 1500-2100*F. TO SOFTEN THE STEEL AS WELL AS REDUCING THE CARBON CONTENT. AFTER ANNEALING, THE CAKE-LIKE STRUCTURE IS BROKEN UP BY HAMMER-MILLING TO RESTORE THE AS-ATOMIZED PARTICLE SIZE.

Synthesis of superconducting compounds by explosive compaction of powders

Abstract: SUPERCONDUCTING INTERMETALLIC COMPOUNDS, SUCH AS NB3SN ARE PREPARED BY DISPOSING A FINELY DIVIDED, STOICHIOMETRIC MIXTURE OF ELEMENTAL METAL POWDERS IN A CONTAINER, SURROUNDING THE CONTAINER WITH AN EXPLOSIVE AND DETONATING THE EXPLOSIVE. THE RESULTING EXPLOSIVE SHOCK WAVE PROVIDES THE NECESSARY REACTION CONDITIONS FOR COMPOUND FORMATION.

SYNTHESIS OF Nb3Sn BY SHOCK WAVES

Abstract: Superconducting Nb-Sn intermetallic compound synthesis from elemental powders by converging shock waves

Powder metallurgy aluminum parts

Abstract: A powder metallurgy aluminum article and a method of producing it in which a lubricant is mixed with an aluminum powder of selected particle shape and size and the mixture is cold compacted to a desired density. The compacted mixture is then sintered in air or a protective atmosphere. The sintered article may then be coined or sized.

Heat tube - with dual porosity capillary structure

Abstract: Heat tube with a capillary part, the diameter of which in the heat-absorbing zone is small and is large in the heat-delivery and transport zones. The capillary structure of the inside wall, and the front walls of the tube are prepd. by powder metallurgy using Cu, Ni, Ti, Al or stainless steel powder.

Composition and properties of the binder metal in cobalt bonded tungsten carbide.

Abstract: The properties of tungsten carbide-cobalt hard metals are determined by three parameters: a) properties of the carbide phase, b) properties of the cobalt binder phase and c) interaction between carbide and binder. The present paper is intended as a contribution to the problem of the binder metal. It is known that cobalt is not present in the hard metal in pure form but as a solid solution with tungsten and carbon because of its ability to solve considerable amounts of tungsten carbide at sintering temperature. Since the solubility of WC in Co increases substantially with temperature, the composition of the binder phase at room temperature can be expected to be determined by many features such as sintering temperature and time, rate of cooling, particle size of the carbide used and, consequently, the mean free path in the binder.

New developments in superalloy powders.

Abstract: The advantages of a P/M process for Ni-based superalloys are shown in terms of better homogeneity than cast alloys. By using low interstitial-atomized powders densified by direct extrusion, superplastic structures are developed. The results of a thermo-mechanical process are presented through which large grained or even single crystal structures can be fabricated. Finally, an alloy series made specifically for P/M processes is presented. These alloys have no carbon as atomized, densified or formed. The resultant solution-annealed grain sizes are ASTM 1 to 0. These alloys are subsequently carburized to stabilize the grain boundaries.

Exothermic structuring of aluminum

Abstract: Strongly bonded aluminous bodies with produced by powder metallurgy by blending an amount of nickel powder with aluminum powder at least sufficient to effect the exothermic sintering of a pressed compact of the blended powder by heating the compact in a furnace maintained at a temperature below the eutectic temperature of the aluminum-nickel system and higher than the temperature at which nickel reacts exothermically wth aluminum.

Corrosion resistant powder metal parts

Abstract: A METHOD OF PROVIDING A POWDER METAL ARTICLE SUBJECTED TO A CORROSIVE HALOGEN ION CONTAINING ENVIRONMENT WITH CORROSION RESISTANCE THERETO, WHICH COMPRISES THE STEPS OF: PRESSING METAL POWDER INTO A GREEN COMPACT; SINTERING THE GREEN COMPACT IN A SUBSTANTIALLY NON-OXIDIZING ATMOSPHERE, THEREBY FORMING A SINSTERED ARTICLE; SUBSTANTIALLY IMPREGNATING AND COATING THE SINSTERED ARTICLE WITH AN AQUEOUS ALKALI METAL SILICATE SOLUTION; CURING THE SOLUTION AT A TEMPERATURE OF AT LEAST ABOUT 300*F. TO DRIVE OFF THE WATER RADICAL OF THE SOLUTION, AND RENDER THE ARTICLE POROUS AAND THE SILICATE IMPREGNAT AND COATING WATER INSOLUBLE; AND PLACING THE ARTICLE INTO SERVICE IN A CORROSIVE HALOGEN ION CONTAINING ENVIRONMENT. A PRESSED AND SINSTERED POROUS POWDER METAL ARTICLE COATED BOTH EXTERNALLY AND INTERNALLY ALONG POROUS PASSAGES WITH A CURED ALKALI SILICATE COATING HAVING AN AVERAGE THICKNESS OF AT LEAST 15 MICROINCHES AND WHICH IS CAPABLE OF WITHSTANDING A 5% AQUEOUS SODIUM CHLORIDE SPRAY SOLUTION, WITHOUT SHOWING SIGNS OF RUSTING, PITTING OR STANING AT NORMAL VISUAL LEVELS, FOR A PERIOD IN EXCESS OF 100 HOURS, IN ACCORDANCE WITH TESTING PROCEDURES ESTABLISHED BY ASTM DESIGNATION B117-64.

Creep behavior of electron-beam-melted rhenium

Abstract: Creep deformation in electron-beam-melted polycrystalline rhenium sheet was evaluated at 2200° to 4200°F (1477° to 2588°K) and 4 to 40 ksi (28 to 276 MN per sq m). Comparisons were made with powder metallurgy rhenium under similar conditions. Changes in creep-rupture behavior resulting from electron beam melting of rhenium were greater ductility, higher primary creep rate, and longer rupture life, especially at lower temperatures. The activation energy for creep was 72 kcal per mole for electron-beam-melted rhenium and 64 kcal per mole for powder metallurgy rhenium.

A Correlation of Mechanical Properties of Sintered U-700 Powder with Particle Boundary Morphology

Abstract: Difficulties in forging cast superalloys have caused the Air Force and engine manufacturers to concentrate their efforts to develop a powder metallurgy preform which would be suitable for forging. superalloys have developed, large concentrations of alloying additions have been made to improve high temperature properties. These increased additions have promoted segregation within the cast alloy. This segregation has narrowed the forging temperature range and resulted in alloys which are difficult to forge. Since a powder particle is an extremely small casting, segregation is restricted to each particle of powder. The fine particles with their microsegregation then facilitate complete homogenization of solubles. This in turn provides a more efficient utilization of alloying elements and implies that the optimum alloy composition for superalloy powders may be different than present alloys which are now fabricated by the cast/forge process. Similarly, it might be suspected that heat treatment response could be different for a powder compact because of the homogeneity of the powder and the increased degree of supersaturation.

Study on Spark sintering Method with Nickel Powder

Abstract: For the purpose of an effective spark sintering, differences of sintering state by the graphite and insulating dies, are investigated with Ni powder. Main results obtained are as follows.(1) In the case of graphite dies, almost all the initial electric current goes through this dies and nickel powders are heated by this graphite mold. We may not expect the powder itself as a main heater at the first stage of sintering. Temperature distribution in the specimen is small and sintering time is very short (10-15 see).(2) In the case of insulating die, there exists a critical pressure (below which the current path melts but other part keeps its original powder state) and it is impossible to set the primary pressure considerably low. This results in the slow temperature rise and eventually makes the sintering time longer (40-80 see). Temperature distribution in the specimen is larger than in the case of graphite die.

Machining sintered powder metal

Abstract: A method of providing a machined powder metal article, which comprises the steps of: pressing metal powder into a green compact; sintering the green compact in a substantially non-oxidizing atmosphere; substantially impregnating and coating the sintered compact with an aqueous alkali metal silicate solution; and machining the sintered compact, thereby forming a machined article.

The influence of silicon and other elements in controlling interparticle friction and sintering of beryllium powder

Abstract: The effect of small additions of activating elements such as silicon on the consolidation behaviour of beryllium powder has been investigated. Evidence is given that compacts of activated powder have more uniform high density than those produced from non-activated material. Studies carried out on prepared beryllium discs show that silicon modifies the micro-structure of the surface layer of beryllium oxide and, in consequence, affects its sliding behaviour and bonding characteristics.From these results a model is proposed to account for the observations made on both sintered and hot-pressed beryllium which leads to the conclusion that, in addition to interparticle bonding, some measure of metal particle rearrangement is necessary for maximum densification. Activating elements may, in modifying the surface characteristics of the individual powder particles, assist in achieving an improved balance between particle sliding on the one hand and interparticle bonding on the other. In taking into account...

Process for the production of iron powder from aman oxide

Abstract: 1,219,674. Producing iron powder. BRITISH IRON & STEEL RESEARCH ASSOCIATION. Sept.30, 1969 [Oct. 7,1968], No.47530/68. Heading C7D. Iron powder suitable for use in powder metallurgy is produced by reducing an oxide produced by the Aman process (roasting of iron chloride residues from HC1 pickling baths) in a reducing atmosphere at elevated temperature under conditions which give rise to partially sintered iron powder. A thin bed of oxide may be reduced in a continuous band furnace by hydrogen at 860‹-1200‹C, and the initial oxide preferably has a density of at least 0.65 with at least 75% of the particles between 100 and 350 BSS mesh. Sulphur may be added to the ore as such or as ferric sulphate to facilitate reduction. The product may be ball-milled to increase its density.