Showing papers on "Powder metallurgy published in 1983"

Method of consolidating a metallic body

Abstract: A method of consolidating a metallic body is disclosed. The method comprises the steps of forming an article of manufacture from powdered metal; sintering the article of manufacture so as to increase the strength thereof; coating the article with a sacrificial layer of ceramic; providing a bed of heated, generally spheroidal ceramic particles; compacting the coated article of manufacture embedded in the heated bed under pressure to thereby consolidate the article into a dense, desired shape; and, removing said sacrificial coating such that the surface of the article remains substantially free of process-related imperfections.

Method of consolidating a metallic or ceramic body

Abstract: A method of consolidating a metallic or ceramic body is disclosed. The method comprises the steps of forming an article of manufacture from powdered metal; sintering the article of manufacture so as to increase the strength thereof; providing a bed of heated, generally spheroidal ceramic particles which have been coated with a thermally stable lubricant; and compacting the article of manufacture embedded in the heated bed under pressure to thereby consolidate the article into a dense, desired shape.

Dispersion strengthened metal composites

Abstract: There is provided a substantially fully dense powdered metal composite comprising a highly conductive metal or metal alloy matrix having dispersed therein discrete microparticles of a refractory metal oxide and discrete macroparticles of a mechanical or physical property-conferring additive material. The respective components undergo minimal alloying or interdispersion because sintering is not utilized in forming the composite. These composites are characterized by high thermal or electrical conductivity and a desired property (controlled thermal expansion, high strength, wear and arc erosion resistance, or magnetic) attributable to the composite forming material, like refractory metal, alloy, or compound. The composites are useful in forming lead frames for integrated circuit chips, electric lamp lead wires, electrical contact members, and discrete component leads.

Surface modified powder metal parts and methods for making same

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

Composite metallic and non-metallic articles

Abstract: The invention is concerned with the problem of joining ceramic components to metal components. A composite ceramic-metal component is proposed, e.g. a rotor disc for a gas turbine engine (see FIG. 2), in which the main body of the component is made from a ceramic, e.g. Silicon Nitride, but the areas at which attachment is to be made to a metal component is formed from metal compacted onto the ceramic by a hot isostatic pressing process. The method of manufacture described is to form a ceramic core with holes appropriately positioned in it where a connection is to be made to another component, surround the core with a powdered metal, e.g. a Nickel-based superalloy, ensuring that the holes also fill with powder, compacting the powder by hot isostatic pressing, and then machining away unwanted metal.

Microstructures and mechanical properties of hot isostatically pressed powder metallurgy Alloy APK-1

Abstract: The influence of Hot Isostatic Pressing (HIP) and heat treatment parameters on the microstructure and mechanical properties of powder metallurgy alloy APK-1 (a low carbon modification of Astroloy) has been investigated. Poor mechanical properties result if carbide networks are present along the prior particle boundaries (PPBs). These networks which form during powder consolidation can be avoided by manipulating HIP parameters. Heat treatments which produce a large volume fraction of fine γ’ make this alloy susceptible to environment-assisted tensile embrittlement around 760 °C.

Scaleup of powder metallurgy processed Nb-Al multifilamentary wire

Abstract: Powder metallurgy processed Nb-Al superconductIng wires were fabricated from billets up to 45 mm o.d. with nominal areal reduction ratios, R, up to 2 × 105, Nb powder sizes from 40 to 300 μm from various sources, Al powder sizes from 9 to 75 μm, Al concentrations from 3 to 25 wt % Al and with a wide range of heat treatments. All the compacts used tap density powder in a Cu tube and swaging and/or rod rolling and subsequent wire drawing. Both single strand and bundled wires were made. Overall critical current densities, J c , of 2 × 104A/cm2at 14 T and 104A/cm2at 16 T were achieved for 6 to 8 wt % Al in Nb.

Cermets having transformation-toughening properties and method of heat-treating to improve such properties

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.

Aluminum powder metallurgy

Abstract: A process for making a workpiece suitable for being hot worked to produce a wrought metal poduct is described. Aluminum alloy powder is cold compacted and then heated in an inert environment to provide a sinter-sealed shape. The resultant workpiece may then be subjected to conventional processing to produce the desired wrought product.

Electrical conductors arranged in multiple layers

Abstract: A low-cost electrical conductor is prepared by applying a mixture of a metallic powder and a polymer on a substrate, curing the polymer, effecting an augmentation replacement reaction to replace some of the metallic powder with a more noble metal in such a way that the total volume of deposited metal at the surface exceeds that of the original metal powder replaced, and thereafter applying a dielectric material to selected areas of the conductor thus formed. Imperfections such as pin holes and screen marks can be eliminated by heating the dielectric material to cause a degree of flow. Multiple layer interconnected conductors can be prepared by reapplying the mixture of metallic powder and polymer such that a portion thereof contacts the first prepared conductor, curing the polymer and effecting an augmentation replacement reaction with a metal which is more noble than the powder metal and the replacement metal of the first conductor.

Preparation of titanium diboride powder

Abstract: Finely-divided titanium diboride or zirconium diboride powders are formed by reacting gaseous boron trichloride with a material selected from the group consisting of titanium powder, zirconium powder, titanium dichloride powder, titanium trichloride powder, and gaseous titanium trichloride.

Fe-Ni-Mo magnet alloys and devices

Abstract: Essentially cobalt-free alloys are disclosed having a coercive force which is greater than or equal to 40 oersteds and having a magnetic squareness which is greater than or equal to 0.6. Such alloys comprise Fe, Ni, and Mo, and their approximate compositions are specified by 16-30 weight percent Ni and 3-10 weight percent Mo, remainder essentially Fe. Disclosed alloys are useful in memory and security devices.

Engine cylinder liners based on aluminum alloys and intermetallic compounds, and methods of obtaining them

Abstract: The invention relates to cylinder liners for internal combustion engines comprising a matrix based on aluminum alloys of high mechanical strength, obtained by powder metallurgy, and methods of producing them. The liners comprise a dispersion of grains of an added intermetallic compound, apart from the dispersion of such intermetallic compounds as may exist in the alloy, the added compound having a melting temperature of over 700° C. The liners are obtained by extruding or sintering a mixture of powders. The liners of the invention may be used particularly in the automobile industry and in any kind of industry where liner-piston units of good compatibility must be obtained from aluminum alloys.

Method of sintering stainless steel powder

Abstract: A stainless steel powder is mixed with at least a Ni--Mn and a Ni--Cr powder, and the powder mixture is formed by loose packing into a required configuration. The powder mixture is sintered in a non-oxidizing atmosphere at the melting point of the Ni--Mn powder or at a higher temperature thereby to obtain a porous body.

Amorphous metal powder for coating substrates

Abstract: The present invention is for a flat B containing amorphous powder based in Fe, Ni, Co or a combination thereof; a coating resulting from deposition of the powder; and a method for depositing the powder. The composition of the powder and the resulting coating consists essentially of the formulation: (Fe,Ni,Co)bal Cr0-20 (Mn,Mo,W)0-35 (B,Si,C)5-25 (Al,Ti)0-10 where the subscripts are in atomic percent and with the proviso that 4≦B≦15, and that the balance will exceed 50%.

Powder metallurgy : applications, advantages, and limitations : a project of the Powder Metallurgy Committee of the Mechanical Working and Forming Division of American Society for Metals

Abstract: Powder metallurgy: applications, advantages, and limitations: a project of the Powder Metallurgy Committee of the Mechanical Working and Forming Division of American Society for Metals , Powder metallurgy: applications, advantages, and limitations: a project of the Powder Metallurgy Com... , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Method of preventing segregation of metal powders

Abstract: The present invention provides a method of preventing the segregation of powders of different specific gravities in a metal powder composition The powder metal is admixed with the powders of lesser specific gravities, and furfuryl alcohol is added at the same time While mixing, an acid is added to react with the furfuryl alcohol to convert the alcohol to a solid resin film on the powder metal particles The powders of lesser specific gravities are bonded to the metal powder particles by the resin, and segregation of the metal powder and the lighter powders is eliminated

Method of the preparation of high density sintered alloys based on iron and copper

Abstract: A method of the preparation of an improved high-density sintered alloy composed mainly or iron and up to 50 wt. % of copper, in which boron is added in an amount of no less than 0.03% to suppress or limit the copper growth phenomenon during sintering. The alloys prepared by the present method undergo less dimensional changes during sintering and are thus of a very high density as compared with the conventional alloys of the same type.

Liquid Phase Sintering of Nickel Base Superalloys

Abstract: (1983). Liquid Phase Sintering of Nickel Base Superalloys. Powder Metallurgy: Vol. 26, No. 1, pp. 17-22.

Submicron filament multistrand powder metallurgy processed Cu-Nb-Sn wire

Abstract: Submicron size ultrafine Cu-Nb-Sn superconducting wire has been fabricated by the powder metallurgy process simulating large scale industrial fabrication using the bundling technique. Starting copper and niobium powders ranged from 250 to 500 μm. Both external and tin core processed wires were fabricated with overall current densities of J_{c} \sim 2-3 \times 10^{4} A/cm2at 14 T, demonstrating that both particle size and billet can be scaled up to large scale fabrication.

The Direct Powder-Rolling Process for Producing Thin Metal Strip

Abstract: The direct powder-rolling process has the potential to provide strip/sheet/foil products from a wide variety of unique powder metallurgy alloys. Alloy powder particles are directly roll-compacted to form strip or sheet of near-final thickness. Subsequent heat treatment and rolling produces material which has properties equivalent to those of the ingot metallurgy (I/M) counterpart. Following a general review of the process, microstructures of powder and roll-compacted material, and their relationship to properties, are discussed.

Microcrystalline Iron-Base Alloys Made Using a Rapid Solidification Technology

Abstract: Initial results of investigation on selected iron-base alloys using a rapid solidification powder metal technology currently being developed at Marko Materials under a DARPA/AMMRC program are reported. The various alloys studied include commercial precipitation hardenable (PH) stainless steels, iron-aluminide-base alloys and high-speed steels. These alloys were modified with specific amounts of boron and processed by melt spinning as rapidly solidified powders followed by hot extrusion. The consolidated alloys were subjected to various heat treatment procedures for optimum mechanical properties. A 30–35% improvement in tensile strength combined with good ductility has been achieved in boron modified PH stainless compared to the conventional alloys. Rapidly solidified Fe-Al-B alloys show high specific strength and modulus of elasticity in the temperature range 1000–1400°F. The other noteworthy attributes of the iron-aluminide-base alloys are outstanding oxidation resistance, good low-cycle fatigue strength, and high thermal stability at elevated temperatures. Very high elongations, typically up to 280%, were achieved in these alloys at high temperatures (1600°F), indicating the possibility of superplastically hot forming these materials. A rapidly solidified boron-modified tool steel showed significant improvement in tool life in cutting (turning) tests, compared to its commercial counterpart.

Heat treating plate for powder metallurgy

Abstract: PURPOSE:To provide a titled treating plate which is inexpensive and has many service times by forming the surface of a base body of carbon or graphite into a waveform and forming a coating layer of the composite oxide of ZrO2 and a metallic oxide, etc. having a spinnel structure on the rugged surface to an adequate thickness. CONSTITUTION:The surface of a base body which is a carbon or graphite plate is formed into a waveform and a coating layer of the composite oxide of ZrO2 and a metallic oxide having a spinnel structure of further contg. Y2O3 or CaO is coated to 10-1,000mu thickness on the rugged surface thereof in a heat treating plate for powder metallurgy formed by coating the oxide on the surface of said base body. The heat treating plate which is inexpensive, is hardly comsumable by oxidation and permits an increase in service times without stripping of the oxide coating layer on account of cracking is thus obtd. Said coating layer can be formed by melt spraying the oxide of ZrO2, etc. and MgAlO4 is adequately used for the oxide having the spinnel structure. The ratio between ZrO2 and the oxide of the spinnel structure is preferably regulated to 1/5-5/1 by weight.

Tin core processing of powder metallurgy Cu-Nb-Sn

Abstract: Powder metallurgy processed CuNbSn superconducting wires were fabricated using different internal tin core geometries. Variations of the process included: 1) a single central tin core surrounded by a multifilamentary composite or by a multistran powder composite, and 2) bundled multistrand compacts, each containing a tin core. External Ta or Nb barriers were also incorporated in the wire. Nominal areal reductions of 104to 106were used. Overall critical current densities of 3 × 104A/cm2at 14 tesla were achieved.

Densification of selected areas of powder metal parts

Abstract: A method of preparing a powder metal body such as a gear having adjacent portions of different densities. In the case of a gear, the gear teeth and the root adjacent the gear teeth are provided with the greater density to give the teeth greater impact and wear resistance. The first step comprises forming a powder metal compact by pressing powder metal in a mold (10) with at least one multiple depth punch (11, 14) to produce a compact having a portion of greater length relative to the length of another portion of the compact. The next step is sintering the compact followed by repressing with a punch that applies forces only to the portion of the sintered compact having the greater length.

Oxidation behavior of Fe-Si-Al alloys at 1173-1373 K

Abstract: The oxidation behavior of Fe-Al-Si alloys prepared by ingot metallurgy (IM) and powder metallurgy (PM) in air and oxygen was investigated in the temperature range 1173–1373 K. A fine dispersion of TiB2 in the PM alloys stabilized a fine grain size (<1 Μ) up to 1273 K. Isothermal oxidation tests in air and oxygen at 1173, 1273, and 1373 K were carried out in a thermobalance system and cyclic oxidation tests were carried out in air at 1273 K. The exceptional scale adherence and the extremely low oxidation rates, in both the isothermal and the cyclic tests, of the Al2O3-scale-forming Fe-Al-Si PM alloys makes them strong candidates for use below 1273 K; the IM alloys, in comparison, showed very poor scale adherence. The results suggest that the critical Al content for continuous Al2O3 scale formation at 1373 K is increased by the addition of TiB2. The Fe-8Si PM alloy which forms an SiO2 scale showed improved scale adherence but enhanced scale growth rate compared to the Fe-8Si IM alloy. The grain-growth inhibiting effect of TiB2 was lost in the Fe-8Si PM alloy in oxidizing environments because of Ti transport across the SiO2 scale. All the IM and PM alloys tested showed superior oxidation resistance compared to the 304 stainless steel. The relative rating in terms of decreasing oxidation resistance of the alloys tested is Fe-3Al-5Si PM, Fe-8Al PM, Fe-5Al-3Si PM, Fe-3Al-5Si IM, Fe-8Al IM, Fe-8Si IM, Fe-8Si PM, and 304 stainless steel.

Process for preparation of silicon nitride powder of good sintering property

Abstract: A silicon nitride powder having an enhanced sintering activity is prepared by heating a mixture of a nitrogen-containing silane compound and a sintering aid in a non-oxidizing atmosphere.