Showing papers on "Aluminium alloy published in 1986"

Aluminium alloy—rice husk ash particle composites

Abstract: Sous-produit agricole tres abondant, dont les cendres sont riches en silicium. Fabrication d'un composite ayant comme matrice metallique l'alliage LM 13 (contenant 10 a 12% de Si) et 3% en poids de ces particules. Microstructure

Aluminium alloy-solid lubricant talc particle composites

Abstract: This paper describes the method of synthesizing cast aluminium alloy talc particulate composites and their mechanical and wear properties. Talc particles were characterized using X-ray diffraction, infrared spectroscopy and differential thermal analysis techniques. Composites with two Al-Si alloys (LM 13 and LM 6) as matrices were prepared by heating the molten alloys to 750° C and adding the preheated talc powder (−150 + 50 μm size) after creating a vortex by mechanically stirring the melt. Simultaneous addition of 2 wt% Mg was found to facilitate the introduction and dispersion of talc particles in molten Al-Si alloys. Composites containing 2.8 wt % talc in LM 13 and 2 wt % talc in LM 6 have been prepared. Optical micrographs of composites revealed uniform distribution of talc particles. Hardness and tensile strength of LM 13+2.8% talc were 85 BHN and 126 MPa, respectively. After suitable heat treatment hardness and strength were increased to 125 BHN and 211 MPa respectively. Wear rates of LM 13+2.8 wt% talc and LM 6+2 wt % talc composites were found to be 22 to 30% less than the wear rates of corresponding base alloys without any dispersions.

Cryogenic mechanical properties of Al-Cu-Li-Zr alloy 2090

Abstract: The mechanical properties of aluminum-lithium alloy 2090-T8E41 were evaluated at 298 K, 77 K, and 4 K. Previously reported tensile and fracture toughness properties at room temperature were confirmed. This alloy exhibits substantially improved properties at cryogenic temperatures; the strength, elongation, fracture toughness and fatigue crack growth resistance all improve simultaneously as the testing temperature decreases. This alloy has cryogenic properties superior to those of aluminum alloys currently used for cryogenic applications.

Growth of cube grains during recrystaIIization of aluminium

Abstract: Recrystallization in a commercial purity aluminium alloy has been investigated. The development of recrystallization texture and the rate of grain growth during the transformation has been followed by selected area channelling patterns in a STEM microscope. It is documented that the volume fraction of the cube texture component increases at a higher rate than the other texture components during the recrystallization reaction. This behaviour is interpreted as a preferential cube site localization effect.MST/218

Microstructural characterization of two lithium-containing aluminium alloys

Abstract: The microstructures of two lithium-containing aluminium alloys have been investigated. The two alloys were an Al-Li-Mn alloy, heat treated to provide an under-aged, peak-aged and an over-aged condition, and a commercial Al-Cu-Li alloy, 2020, heat treated and aged to contain ordered precipitate structures. It was observed that both materials were recrystallized with fairly large grains. The Al-Li-Mn material had a high volume fraction of Al6Mn dispersoids and the Al-Cu-Li alloy had a substantial volume fraction of coarse intermetallic particles and intermediate size disperoids. The major strengthening precipitates were identified from brightfield and dark-field images and selected-area diffraction patterns taken in the transmission electron microscope. Precipitate-free zones were found to be present in both the Al-Li-Mn and Al-Cu-Li alloys. The results of this study suggest that the peak-aged Al-Cu-Li alloy and the under-aged and peak-aged Al-Li-Mn alloys enhance deformation to occur primarily by planar slip, and the larger particle size and interparticle spacing of the over-aged Al-Li-Mn promotes a combination of planar slip and Orowan looping.

Rolled aluminium alloy strip for forming and method for making

Abstract: Rolled strips of aluminum alloy having improved formability and bake hardening ability are suitable for use as automobile body sheets by mechanically forming the strips and baking paint coatings thereto. The alloy consists essentially of, in percents by weight, 1.2-2.5% of Si, 0.15-1.5% of Mg, 0.1-1.5% of Cu, less than 0.2% of Fe, less than 0.05% of each of Mn, Cr, Zr and V, the total amount of Mn, Cr, Zr and V being less than 0.10%, and the balance of aluminum. The strips have a conductivity of up to 50% IACS and a mean grain size of up to 100 µm at a surface. The strips are prepared by casting a molten aluminum alloy, heating the alloy at 480 to 560°C, hot rolling the alloy into a strip such that the residence time in the temperature range of from 480°C to 400°C during hot rolling following the heating step is within 30 minutes, and a solution treatment step including heating the rolled strip at a rate of at least 5°C/sec. to a temperature of 480 to 560°C, holding the strip at the temperature within 60 seconds, and sequentially cooling at a rate of at least 5°C/sec.

Aluminum alloy with superior thermal neutron absorptivity

Abstract: An aluminium alloy with superior thermal neutron absorptivity contains 0.2-30 wt. % of Gd. An aluminium alloy for an wrought material with high-temperature strength contains 0.2-20 wt. % of Gd and 0.5-6 wt. % of Mg. An aluminium alloy for casting contains 0.2-10 wt. % of Gd and 6-12 wt. % of Si.

Method for padding a copper alloy material upon a base of aluminum metal or aluminium alloy using laser beam oscillating transversely to its tracking direction

Abstract: In this method for padding, a layer of a copper type alloy material in powdered form is laid upon a portion of a base of aluminum type metal which is to be padded. Then a laser beam, concentrated to a spot from about 0.5 mm to about 2.0 mm in diameter with an output density of from about 80 watt/mm 2 to about 20,000 watt/mm 2 , is irradiated upon this layer of powdered copper type alloy material upon the base of aluminum type metal. The laser beam and the base of aluminum type metal are relatively moved in a relative longitudinal direction at a longitudinal speed of from about 100 mm per minute to about 3000 mm per minute; and they are also reciprocatingly moved in a relative direction substantially transverse to the longitudinal direction at an transverse oscillating frequency of above about 80 Hz. Thereby, good padding efficiency is obtained. The copper type alloy material may initially be applied as a powder including a binder and then be dried, before the laser irradiation; or it may be applied automatically substantially during the laser irradiation.

Method of forming a composite layer by laser irradiation on an aluminium alloy substrate surface

Abstract: In this method for forming a composite layer on the surface of an aluminum alloy substrate, a powder mixture, containing a powder of a ceramic carbide of a metal and a metallic powder containing silicon and a metal element which forms an inter metallic compound with silicon, is disposed upon the surface of the aluminum alloy substrate. This powder mixture is then irradiated with a laser, so that the metallic powder in it is melted and fused together with a surface portion of the aluminum alloy substrate, so that these two are alloyed together. The powder mixture may be a powder of an alloy of silicon and the metal element which forms an inter metallic compound with silicon, or alternatively may be a mixture of a powder of silicon and a powder of the metal element which forms an inter metallic compound with silicon. The metal element which forms an inter metallic compound with silicon may be copper or may be molybdenum; and the ceramic carbide of a metal may be titanium carbide or may be molybdenum carbide.

Sintered aluminium alloy

Abstract: A sintered aluminium alloy is formed from a green compact containing 4-12% by weight of an active ingredient consisting of one or more of iron, nickel and chromium, the balance being aluminium or aluminium based alloy containing at least 90% aluminium. The active ingredient has a particle size of not greater than 60 microns, the aluminium or aluminium alloy a particle size not greater than 120 microns, and the compact is formed with a compaction pressure in the range 60-120 MPa. The compact is sintered at a temperature which remains below the melting point of pure aluminium after initiation of an exothermic reaction between the aluminium and the active ingredient. The resulting alloy contains dispersed zones of intermetallic compounds in a matrix of aluminium or aluminium based alloy.

Effect of cutting speed and tool rake angle on residual stress distribution in machining 2024-T351 aluminium alloy — unlubricated conditions

Abstract: The residual stress distribution in the machining of 2024-T351 aluminium alloy was measured using an electrolytic etching technique. Ring-shape specimens were machined under unlubricated orthogonal conditions with high-speed steel tools having rake angles of 10, 15, 20 and 25° at cutting speeds ranging between 0.5 and 1.25 m sec−1. The results of the investigation show that the residual stresses are compressive at the machined surface and decrease with depth beneath the machined surface. The maximum (near-surface) residual stress and the depth of the severely stressed region increase with an increase in the cutting speed. There seems to be little change in the residual stress distribution due to a change in the rake angle. The results are interpreted in terms of the variations in the amount of surface-region deformation produced by changes in cutting conditions.

Aluminium alloy-silica sand composites: preparation and properties

Abstract: Ceramic particulate composites containing up to 25 wt% silica sand in commercially pure aluminium (LM-O) and its eutectic silicon alloy (LM-6) were prepared by liquid metallurgy techniques. Pre-treated sand particles of sizes ranging from −180 to +90μm were added to the alloy melts, followed by pouring the resulting mix into permanent moulds. Quantitative metallographic examination revealed that sand particles were uniformly distributed in both types of cast composite. Scanning electron microscopic examination of the composites showed voids around the sand particles. Tensile specimens, when fractured in an Instron machine, showed an interfacial mode of failure of the composite without affecting the sand particles, indicating poor bonding with the matrices. The hardness of LM-O alloyed with magnesium increased from 52 to 78 BHN, whereas the ultimate tensile stress (UTS) decreased from 92 to 62 MPa as a result of the addition of 20 wt% sand particles. In the case of LM-6-sand composites, the hardness remained almost constant but the UTS decreased from 184 to 112 MPa with the addition of 20 wt% sand particles. The compressive strength of both types of composite also decreased as a result of sand additions. However, a favourable effect of magnesium alloying on the strength of the cast composite was also observed.

Corrosion-resistant aluminium core alloy

Abstract: An aluminium alloy contains vanadium as an alloying element. The vanadium is preferably at a concentration in the range from 0.02% to 0.4% by weight and imparts corrosion-resistance to the alloy, particularly when it is used as a core alloy in a vacuum brazing sheet. Further corrosion resistance is also achieved by processing the alloy or brazing sheet in such a manner that the final processing step is a cold working effected so as to reduce the sheet by 10% to 20%.

Dependence of fatigue life on the surface integrity in the machining of 2024-T351 aluminium alloy — unlubricated conditions

Abstract: An experimental investigation was conducted to study the dependence of fatigue life on the surface integrity in the machining of 2024-T351 aluminium alloy under dry unlubricated conditions. Cutting speeds ranging from 100 to 250 ft min−1 (30.48 to 76.2 m min−1 and tool rake angles ranging from 10 to 30° were used. The results of the investigation show that the damage in the surface due to machining consists of a wide variety of defects such as cracks, long straight grooves, cavities, microcracks and macrocracks, and severe plastic deformation, etc. The severity of the damage decreases with an increase in the cutting speed and tool rake angle. An increase in the cutting speed or tool rake angle resulted in an increase in the fatigue life of the specimen.

Tensile behaviour of mechanically alloyed precipitation hardened aluminium alloy IN 9021

Abstract: The room temperature tensile behaviour of the mechanically alloyed aluminium alloy IN 9021 was studied. Precipitation hardening increases the tensile strength from 485 MN m−2 in the as-extruded condition to 620 MN m−2. Mechanical alloying produces a fine grain size, a high dislocation density, and a dispersion of ultrafine Al2O3 and Al4C3particles. During annealing at temperatures up to the solidus, recovery and continuous recrystallization take place, but there is no significant grain growth. High-temperature tensile testing showed that the precipitation hardened alloy loses strength more rapidly than the as-extruded alloy, and is the weaker at temperatures > 180°C. The as-extruded alloy has a maximum strain rate sensitivity of 0·13 at 300°C. This lack of superplasticity, in spite of the fine grain size, is believed to be due to the high hardness of the pinning oxide and carbide particles, which tend to prevent easy slip and grain boundary sliding.MST/423

Properties of Particles Produced by Different Rapid Solidification Techniques

Abstract: Two methods of producing PM rapidly solidified 7XXX series aluminium alloy are described: melt spinning (ribbons → flakes) and air atomization (powders). The microstructure and properties of particles (shape, size distribution, alloying concentration profiles) are discussed with regard to cooling rate. The reseach also emphasizes the importance of particle oxidation and its influence on their behaviour during subsequent processing. The trade-offs required between the various particle properties that are considered suggest that melt spun material should be recommended for heat treatable aluminium alloys, while powders should be used for non-heat treatable alloys. PM/0372

Laminated material for slide bearing elements with an anti-friction layer of an aluminium-based bearing material

Abstract: In a laminated material for slide bearing elements, having according to the parent patent, on a metallic support layer, an antifriction layer consisting of an almost homogeneous aluminium alloy which contains additions of 1 to 3% by weight of nickel, 0.5 to 2.5% by weight of manganese and 0 to 2% by weight of lead in the aluminium together with the usual permissible impurities, a copper addition of between 0.02 and 1.5% by weight in the aluminium alloy is additionally provided. This copper addition increases the hardness, the tensile strength and the fatigue strength of the anti-friction layer formed on the aluminium alloy, while retaining good elongation values. The hard particles present in the anti-friction layer have, as in the parent patent, substantially a particle size of

Temperature programmed desorption studies of outgassing of aluminium powder

Abstract: The mechanical properties of powder metallurgy (P.M.) aluminium alloys may be influenced considerably by the hydrogen content. To obtain high-quality alloys, it is necessary to optimize the degassing of the powder before sintering. Such a process involves an understanding of the mechanism of the desorption of H2 from the surface of the powder.

Method for producing a multi-layer slide bearing material needing little maintenance

Abstract: 1. Process for producing a maintenance-free multilayer sliding bearing material, consisting of a combination of a metal backing made of steel, bronze or a high-strength aluminium alloy, provided with a rough primer layer (2), preferably a 0.1 to 0.35 mm thick, porous sinter-bonded bronze layer, iron layer, or aluminium alloy layer, and a bearing layer (3) consisting of a matrix (4) of polytetrafluoroethylene (PTFE), with which material the valleys of the rough primer layer are also filled and which may also optionally contain friction-reducing and wear-inhibiting additives of lead, molybdenum disulphide, graphite, carbon fibres, glass fibres, ceramic fibers, glass spheres, hollow ceramic spheres, barium sulphate, zinc sulphide, lead borosilicate, individually or in combination in a quantity of 5 to 40 % weight, characterized in that the PTFE, which has a grain size of =< 35 mu m, is moulded with an admixed extrusion assisting agent into a preform, said preform is extruded into a strip 1.5 to 5.0 mm thick, the strip is formed into a sheet 0.5 to 3.0 mm thick by conditioning calendering, the sheet, which is heated to 70 to 90 degrees C, is rolled on to the rough primer layer of the metal backing, which has been heated to 130 to 180 degrees C with a decrease in thickness to 0.1 to 1.0 mm, and subsequently the PTFE is sintered by continuous heating to approximately 400 degrees C and maintaining at this temperature for a short time.

Aluminum alloy substrate for lithographic plate and production thereof

Abstract: PURPOSE:To obtain a uniform electrolytic roughened surface with a little quantity of charge electricity and to improve a lithographic plate in plate wear and resistance to stains on non-image areas in printing, by using an aluminum alloy containing Fe, Mg, Sn, Si, and Cu in specific ratios with the content of simple Si less than a specific amount. CONSTITUTION:The composition of an aluminium alloy substrate for lithographic plate is determined as follows: 0.05-0.5% of Fe, 0.7-5% of Mg, 0.01-0.2% of Sn, 0.2% or less of Si, and 0.05% or less of Cu are contained, the remainder is made of Al and an unavoidable impurities, and simple Si is contained 0.012% or less. The impurities of 0.05% or less of Mn, 0.05% or less of Cr, and 0.05% or less of Zn contained in the aluminum alloy cause no particular problem. A uniform roughened surface can be formed by applying electrochemical surface- roughening treatment to the substrate with a little quantity of electricity. In addition, a lithographic plate making use of the substrate is superior in resistance to stains on non-printing areas in printing as well as in plate wear and strength.

Clustering in Al–3Cu–0·1 Be

Abstract: The aging behaviour of Al–3Cu and Al–3Cu–0·1Be alloys has been investigated using microhardness and transmission electron microscopy techniques. The Al–3Cu–0·1 Be alloy was found to have a significantly higher hardening rate than the Al–3Cu alloy at room temperature and 110°C. An Al–0·2Be alloy showed no age hardening tendency at room temperature. The hardening in Al–3Cu alloy is the result of Guinier–Preston (GP) zone formation; no GP zones were observed in Al–3Cu–0·1Be alloy aged at room temperature and 110°C, and an additional aging at 150°C was required to initiate GP zone formation. The higher hardening rate for the Al–3Cu–0·1 Be alloy is attributed to the early and extensive formation of vacancy loops adjacent to network dislocations, the loops acting as barriers to the glide of network dislocations. The formation of Cu–Be–vacancy clusters may be the cause of the accelerated hardening rate, and this is discussed.MST/309

A New Aluminum-Base Alloy with Potential Cryogenic Applications

Abstract: An Al-Fe-Ce alloy has been recently demonstrated to be suitable as a matrix material for a composite conductor with high-purity aluminum filaments which can be used in devices operating at liquid hydrogen temperatures. The alloy is lightweight and has high strength, but just as importantly, its major alloying elements (Fe and Ce) are practically diffusionless in Al. The material was initially synthesized by ALCOA using powder metallurgy. Dynamic recrystallization processes were further developed at the Air Force Materials Laboratory, resulting in a more homogeneous microstructure. This paper describes mainly the results of microstructural, electrical resistivity, and low temperature heat capacity measurements on samples before and after dynamic recrystallization.