Showing papers on "Powder metallurgy published in 1979"

Analytical Study of Effects of Pore Geometry on Tensile Strength of Porous Materials

Abstract: (1979). Analytical Study of Effects of Pore Geometry on Tensile Strength of Porous Materials. Powder Metallurgy: Vol. 22, No. 3, pp. 119-123.

Products made by powder metallurgy and a method therefore

Abstract: An article such as a gas turbine rotor blade or bladed rotor is made by consolidation of metal powders contained in a mould using the technique of hot isostatic pressing. Different properties are produced in different portions of the mould corresponding to those parts with either metal powders of different alloys or with metal powders made from one alloy but differently pretreated, e.g. by rolling, to impart mechanical strain into the powders.

High‐current A‐15 microcomposite materials

Abstract: Powder metallurgy is used as an alternative process to produce Nb3Sn and V3Ga composite superconductors with large critical transport currents in magnetic fields above 15 T. Whereas for a Cu–30 wt.%Nb +Sn composite the overall current density Jc amounts to 1.0×108 A/m2 at 16 T, values in excess of 4×108 A/m2 (16 T) are observed for Cu–30 wt.% V+Ga composites.

Internal combustion engine tappet comprising a sintered powdered metal wear resistant composition

Abstract: An internal combustion engine tappet comprising a sintered powdered metal wear resistant composition having a matrix formed from iron powder, carbon in the range of 0.50-1.0% by weight, and a ferroalloy powder with a mesh size of +50-325 acting as a nucleus for diffusion of the alloying metal into the surrounding iron particles. The alloying metal in the composition is in the range of 1-10% by weight and is selected from the group consisting of chromium, titanium, boron, vanadium, columbium, molybdenum, tantalum and tungsten. The iron, carbon and ferroalloy are briquetted at a pressure of 40-60 tons/sq.in. and sintered, in solid phase, at a temperature of 2000°-2100° F. in a reducing atmosphere. The resulting product is heterogeneous and has hard ferroalloy nuclei and interconnected porosity with a density at the tappet wear surface of approximately 6.8-7.0 gm/cc.

Sintered ferromagnetic powder metal parts for alternating current applications

Abstract: A method of making a metal core for alternating current applications by powder metallurgy is disclosed. Ferro-magnetic powder is pressed into a cross section of the core, with the thickness of the cross section approaching that below which the green density is no longer uniform throughout the volume of the part. Additional cross sections are pressed to meet the overall core thickness requirement when the sections are subsequently stacked. The sections are stacked in non contacting relationship and sintered. The sections are separated by an air gap or magnetic insulating medium.

Practical Metallurgy and Materials of Industry

Abstract: 1. Extracting Metals from Ores. 2. Casting Processes. 3. The Physical and Mechanical Properties of Metals. 4. The Crystal Structure of Metals and Phase Diagrams. 5. Identification and Selection of Iron Alloys. 6. The Manufacturing of Steel Products. 7. The Iron-Carbon Phase Diagram. 8. I-T/T-T-T Diagrams and Cooling Curves. 9. Heat Treating Equipment. 10. Annealing, Stress Relieving and Normalizing. 11. Hardening and Tempering of Steel. 12. Hardenability of Steels. 13. Welding Processes for Iron and Iron Alloys. 14. Identification of Nonferrous Metals. 15. Heat Treating of Nonferrous Metals. 16. Metallurgy of Welds: Nonferrous Metals. 17. Powder Metallurgy. 18. Precious Metal Processing. 19. Corrosion of Metals. 20. Nondestructive Testing. 21. Composite Materials. 22. Plastics and Elastomers. 23. Ceramic Materials. 24. Wood and Paper Products. 25. Adhesives and Industrial Lubricants and Gases. 26. Hardness Testing. 27. Failure Analysis. Appendix 1: Industrial Methods of Specimen Preparation. Appendix 2: Tables. Appendix 3: Self-Evaluation Answers. Glossary. Index.

Corrosion-resistant powder-metallurgy stainless steel powders and compacts therefrom

Abstract: Disclosed is a process for improving the corrosion resistance of a stainless steel powder or compact thereof wherein said powder is produced by atomizing a melt of metals in an oxidizing environment whereby the resulting stainless steel powder is surface-enriched in silicon oxides. The process comprises adding an effective proportion of modifier metal to said melt prior to said atomization, said modifier metal selected from the group consisting of tin, aluminum, lead, zinc, magnesium, rare earth metals and like metals capable of enrichment about the surface of said resulting atomized stainless steel powder and effective under reductive sintering conditions in the depletion of said silicon oxides about said surface; and sintering said resulting atomized powder or a compact thereof under reducing conditions, said sintered powder or compact thereof being depleted in said silicon oxides and the corrosion resistance of said powder or compact thereof being improved thereby.

Superconductivity in filamentary CuNb composites produced by powder metallurgy

Abstract: Composite wires with discontinuous Nb filaments embedded in a Cu matrix are produced by hot extrusion of a powder mixture and subsequent wire drawing. The specimens exhibit superconductivity with critical current densities in zero field up to 4×104 A/cm2 at 4.2 K (after a reduction of the cross‐section area of 5×104 by wire drawing). The origin of resistanceless currents in these materials with only 10 wt% Nb is due to superconducting bridges between the filaments which are formed by the proximity effect. The critical currents are drastically enhanced by a final heat treatment, by which additional Nb precipitates are produced in the Cu marix.

Rare earth-cobalt system permanent magnetic alloys and method of preparing same

Abstract: Permanent magnetic alloys comprising 115-125% rare earth components of which 63-12% is samarium and 05-62% is yttrium; 02-25% hafnium, 195-265% iron, 7-105% copper, and 52-707% cobalt, the ranges of the components being in atomic ratios The alloys are prepared by obtaining 1-50 μm powders of the components, compacting the powder after magnetic field orientation sintering the compacted powders at 1160°-1220° for 1-10 hours, cooling the sintered body at a rate of at least 1° C/second until the temperature is about 900° C, and then annealing the body at 750°-900° C

Effect of thermally induced porosity on an as-HIP powder metallurgy superalloy

Abstract: The impact of thermally induced porosity on the mechanical properties of an as-hot-isostatically-pressed and heat treated pressing made from low carbon Astroloy was determined. Porosity in the disk-shape pressing studied ranged from 2.6 percent at the bore to 1.4 percent at the rim. Tensile, yield strength, ductility, and rupture life of the rim of the porous pressing was only slightly inferior to the rim of sound pressings. The strength, ductility, and rupture life of the bore of the porous pressing was severely degraded compared to sound pressings. At strain ranges typical of commercial jet engine designs, the rim of the porous pressing had slightly inferior fatigue life to sound pressings.

Superconducting properties and annealing behavior of filamentary Cu-based composites produced by powder metallurgy

Abstract: Composite wires with discontinuous Nb filaments embedded in a Cu matrix are produced by hot extrusion of a powder mixture and subsequent wire drawing. Nb 3 Sn layers on the surface of the Nb filaments are formed by a diffusion treatment after plating with Sn. The peculiarities of the powdermetallurgical preparation technique and the origin of resistanceless currents in these materials are discussed. For Cu-Nb composites, it is shown that the critical currents are drastically enhanced by a final heat treatment, by which additional Nb precipitates in the Cu matrix.

Hot pressing and vacuum sintering of fine titanium nitride powder

Abstract: Increasing the specific surface of titanium nitride from 18 to 90 m2/g lowers the initial recrystallization temperature of loosely poured powder from 1300 to 600°K. The temperature at which blanks attain practically 100% density in the hot pressing of finely divided titanium nitride (a starting powder particle size of 0.05–0.07 μm) is 1600°K, which is 500–700°K below the temperature level of full sintering of relatively coarsegrained powders (a particle size of about 0.5 μm). At hot-pressing temperatures above 1800°K a fall in the density of sintered compacts is observed, which is apparently attributable to the beginning of nitrogen evolution from the nitride and also to the formation of microcracks. In vacuum sintering without a plasticizer, crack formation lowering the density of specimens by 3–4% is characteristic of the whole sintering temperature range. The grain size in hot pressing and vacuum sintering is practically the same, being determined chiefly by the sintering temperature and time. At the maximum specimen density the maximum grain size is 20 μm.

Fully dense wear resistant alloy

Abstract: An alloy steel is provided along with a method of making the same. The alloy is heat, wear, corrosion and oxidation resistant, and is preferably made utilizing powder metallurgy techniques. The method involves the addition of carbon and silicon to an iron base alloy containing chromium to improve the properties of the steel.

Powder-metallurgy vanadium-containing tungsten-type high-speed steel

Abstract: A powder-metallurgy produced, vanadium-containing, tungsten-type high-speed steel wherein hardness at elevated temperature is achieved without resorting to conventional, high cobalt contents. This is achieved by providing a critical amount of tungsten and/or molybdenum above that conventionally used in combination with vanadium and carbon in an amount sufficient to combine with the vanadium present and with an excess carbon to provide matrix strengthening. The high hardness and wear resistance at elevated temperature is imparted to the steel by the carbides of vanadium, tungsten and/or molybdenum. Columbium may be substituted for a portion of the vanadium.

Powder metal composition

Abstract: A powder metal composition containing 1.0-2.5% Ni, 0.3-0.7% Mo, 0.15-0.30% Mn, 0.5-1.5% Cu, 0.3-0.7% C, 0.50-1.0% zinc stearate, the balance being Fe.

Production of gear by powder metallurgy

Abstract: PURPOSE:To achieve the improvement in finish dimensional accuracy by providing a pressing margin only to the portions requiring dimensional accuracy at the compression molding prior to sintering and performing dimensional correction to said portions only after the sintering. CONSTITUTION:At the compression molding of a gear 1 by compaction pressure, its tooth flank 2 and tooth face 3 are formed to nearly the same finish sizes and only the tooth surface 4 is molded to a slightly larger size by providing a pressing margin 5 thereto. This is then sintered at the specified temperature. When lubricating oil is sufficiently absorbed in the sintered gear and the gear is pressed in dies, only the pressing margin 5 of the tooth surface 4 receives ironing and its internal structure shrinks, thus the dimensional correction by the compression is effected. Since this method necessitates small pressing force at the die correcting, makes the elastic deformation amount of the dies slight and decreases the spring back amount at the removal from the dies, the assuring of dimensional accuracy becomes easy.

Sintering method for green material of aluminum powder

Abstract: PURPOSE: To uniformalize dimensional change rates over the entire part of an Al molding and prevent the decrease in tensile strength after sintering by burying a green material of Al powder into ceramic powder, and sintering the same in the state that it is held by the ceramic powder. CONSTITUTION: A green material of Al powder molding 1 is bured into ceramic powder 6 and in the state that the molding 1 is held by the powder 6, a vessel 7 is disposed in a sintering furnace and is sintered in an N 2 gas atmosphere. Then, the deformation of the molding 1 at the sintering is suppressed effectively; in addition, the dimensional change rates thereof is made uniform over the entire part of the molding 1 and at the same tme, the dimensional change rate is kept low. nevertheless, the tensile strength of the molding 1 after sintering is made stable and of a high value. COPYRIGHT: (C)1981,JPO&Japio

Process for producing alloy articles by powder metallurgy

Abstract: of EP00056681. Process for the production of alloy bodies by powder metallurgy, characterized in that it comprises preparing, from the constituents of said alloy, a homogeneous mixture of a powder of a first alloy A1 , and a powder of a second alloy A2 , said alloys A1 and A2 comprising all the constituents of said alloy but having a different content of at least one alloying element, whereby alloy A1 forms a liquid phase at a temperature T1 which is lower than the temperature T2 at which alloy A2 forms a liquid phase, and sintering the mixture of said powders under pressure at a temperature between T1 and T2 , holding the mixture at said temperature for at least one hour.

History of the Development of Sintered Permanent Magnets

Abstract: (1979). History of the Development of Sintered Permanent Magnets. Powder Metallurgy: Vol. 22, No. 3, pp. 132-138.

Method of manufacturing powder compacts

Abstract: A method of making high density powdered metal compacts and also a method for making high density powder metal sintered products is disclosed. With respect to the compacts, iron powder of coarse or fine configuration is mixed or coated with a low-melting metal additive selected from the group consisting of tin, copper-tin, copper-lead, or lead in a percentage by weight of 2-5% of the admixture. The admixture is subjected simultaneously to both heat (at a temperature level such that the low-melting alloy is in a liquid phase) and pressure which is in the range of 10-30 tsi. Upon relief of heat and pressure, the agglomerated or compacted product will possess an increased density in excess of 80% and an improved hardness and strength level. With respect to a sintered product, the powder metal is selected to have a fine particle size (average range of about 4-5 microns) and the powder is dry impact coated by ball milling with a low-melting additive such as tin, copper-tin, copper-lead or lead; the coated particles are warm briquetted and subjected to a sintering operation whereby the resulting product has a minimum density of 97% or more.

Heat resistant spring

Abstract: PURPOSE:To enhance the mechanical properties and heat resistance of the resulting lightweight spring by using inorg. fiber such as ceramic fiber or metallic fiber having high elastic modulus and high strength as a reinforcing material for a metal matrix. CONSTITUTION:As a reinforcing material aluminous fiber consisting of >= about 72wt% Al2O3 and <= about 28wt% SiO2 and practically showing no reflection of alpha-Al2O3 in the X-ray structure is used especially preferably. Such aluminous fiber has high tensile strength and high tensile elastic modulus. When aluminous fiber is used as a reinforcing material, a matrix metal used is required to have <= about 1,700 deg.C m.p. in order to avoid the reduction of the high temp. strength of the fiber. A composite material consisting of the fiber and matrix metal is manufactured by liq. metal impregnation, powder metallurgy, deposition, plastic working or other method.

Brazing of Hastelloy X with wide clearance butt joints

Abstract: : Wide clearance butt joints of Hastelloy X base metal were vacuum furnace brazed by first sintering a nickel base powder of high melting point (sinter filler metal) in the joint. This was followed by filling the powder interstices with a nickel base brazing filler metal and a diffusion treatment. Various combinations of sinter filler metals and brazing filler metals were studied by the production and examination of small wafers, which were sintered and brazed. These studies proved to be an efficient means of obtaining valuable information regarding the subsequent fabrication of brazed joints. A technique for brazing butt joints of consistent high quality, with virtually unlimited joint clearance, was developed.

Sigma phase formation in conventional and PM nickel-base superalloys

Abstract: Ageing treatments of up to 5000 h at 705–980°C have been carried out on five chemically modified nickelbase superalloys based on Astroloy (No. I), MAR-M432 (No.2), IN-100 (No.3), PAI0l(No. 4), and AF-2-IDA (No.5). The kinetics and morphology of a-phase formation were examined in two unstable heats (Alloys 3 and 5) processed by powder metallurgy methods and by conventional casting and extrusion procedures. The morphologies of σ were similar in both forms of a given alloy; however, σ precipitation occurred sooner in the powder metallurgyform of Alloy 3 than in the cast and extruded form. Numerical methods based on electron-vacancy concepts predicted σ formation correctly when experimentally determined γ-phase (austenite) compositions were used. Standard methods for computing γ and γ′ contents and compositions were unsuccessful with these modified alloys, and therefore a new regression equation was developed for γ′ contents using a 71 alloy data base. Using this new equation, more accurate γ and γ′ c...

Raw material powder containing molybdenum and tungsten for powder metallurgy and product of powder metallurgy

Abstract: PURPOSE:To enable the alloy powder consisting of Mo-W solid solution and having a specified grain size to be utilized as the raw material for powder metallurgy CONSTITUTION:This alloy powder is a solid solution consisting of Mo and W and the quantity of W in Mo is 5-95 atom weight % Further, the grain size of this alloy powder is below 20mu For example, 54 g of Mo powder and 46 g of W powder are dissolved in aqueous ammonia of 28% When these ammonium salts are neutralized gradually with hydrochloric acid, a needle crystal is deposited By sintering the mixture of these coprecipitated WO3 and MoO3 at 800 degC in the air and reducing it at 1000 degC in the stream of H2 gas, the raw material powder having grain size of 2mu is obtained