EP0045622A1 - Alliages en aluminium durci par vieillissement - Google Patents

Alliages en aluminium durci par vieillissement Download PDF

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Publication number
EP0045622A1
EP0045622A1 EP19810303470 EP81303470A EP0045622A1 EP 0045622 A1 EP0045622 A1 EP 0045622A1 EP 19810303470 EP19810303470 EP 19810303470 EP 81303470 A EP81303470 A EP 81303470A EP 0045622 A1 EP0045622 A1 EP 0045622A1
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EP
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Prior art keywords
alloy
lithium
alloys
temperature
hours
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EP19810303470
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German (de)
English (en)
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EP0045622B1 (fr
Inventor
John Herbert Weber
Joseph Robert Pickens
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MPD Technology Corp
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MPD Technology Corp
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Priority claimed from US06/174,182 external-priority patent/US4532106A/en
Priority claimed from US06/174,181 external-priority patent/US4409038A/en
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/001—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides
    • C22C32/0015—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with only oxides with only single oxides as main non-metallic constituents
    • C22C32/0036—Matrix based on Al, Mg, Be or alloys thereof
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/04—Making non-ferrous alloys by powder metallurgy
    • C22C1/0408—Light metal alloys
    • C22C1/0416—Aluminium-based alloys

Definitions

  • This invention relates to dispersion-strengthened mechanically alloyed aluminium alloys, and methods of producing and age-hardening them.
  • Mechanical alloying techniques are disclosed in, for example, U.S. Patents Nos. 3 591 362; 3 740 210 and 3 816 080.
  • Mechanical alloying is a method of producing composite metal powders with a controlled, uniform,fine microstructure by means of the fracturing and rewelding of a mixture of powder particles during high energy impact milling, e.g., in an Attritor Grinding Mill. The process takes place entirely in the solid state.
  • the repetitive cold welding and fracturing of the powder particles during mechanical alloying of aluminium incorporates dispersoid materials, such as the naturally occurring oxides on the surface of the powder particles, into the interior of the composite powder particles.
  • the incorporated dispersoid particles become homogeneously dispersed throughout the powder particles.
  • metallic alloy ingredients also are finely distributed within the powder particles.
  • Powders produced by mechanical alloying may be subsequently consolidated by known methods such as hot compaction followed by extrusion, rolling or forging.
  • the present invention provides a dispersion-strengthened mechanically alloyed aluminium-lithium alloy which comprises more than 1.5 but less than 3.5 wt % lithium, from 0.4 to 1.5 wt % oxygen, and from 0.2 to 1.2 wt % carbon, the balance being essentially aluminium.
  • the essential components of dispersion strengthened aluminium base alloys of the present invention are aluminium, lithium, oxygen and carbon. Small percentages of these components are present in combination as insoluble dispersoids, such as oxides of lithium.
  • insoluble dispersoids such as oxides of lithium.
  • Other elements e.g., magnesium, iron and copper, may be incorporated in the alloy matrix, e.g., for solid solution strengthening, so long as they do hot interfere with the desired properties of the alloy for a particular end use. Thus the magnesium content should not exceed 1% and the iron content 0.5%.
  • additional insoluble, stable dispersoids may be incorporated in the system to provide increased strength at elevated temperatures so long as they do not otherwise adversely affect the alloy.
  • the lithium content of the alloy must exceed 1.5% and is preferably at least 1.7%. Amounts of lithium up to 1.5% may be present in equilibrium solution, and further amounts may be present in supersaturated solution. A small fraction of the lithium e.g. from 0.03 to 0.5%, depending on the available oxygen content of the powder charge and the total lithium content of the alloy, may be present as a stable insoluble oxide dispersoid which forms in situ during mechanical alloying and/or consolidation and is uniformly distributed in the alloy matrix. This dispersoid is believed to be lithium peroxide, and is particularly effective in increasing the strength of the alloy.
  • the lithium content must not exceed 3.5 wt % since above this figure excessive amounts of 0 phase may form, and the alloy may be embrittled.
  • the lithium content does not exceed 2.8%, as additional strength gained by the use of larger amounts does not compensate for the loss in ductility.
  • the lithium is introduced into the alloy system as a powder (elemental or prealloyed with aluminium), thereby avoiding problems which accompany the melting of lithium.
  • the oxygen content is from 0.4 wt % to 1.5 wt % and preferably does not exceed 1.0 wt %.
  • the oxygen content should be sufficient to provide enough dispersoid for the desired level of strength without being so high as to combine with the lithium in solid solution and reduce the amount of dissolved lithium below the solubility limit, taking into account the amount of lithium which may be present in supersaturated solution.
  • the oxygen level may be up to 1.5 wt %
  • the oxygen content is preferably less than 1 wt %, e.g. 0.4 to 0.5 wt %.
  • the carbon content is from 0.2 to 1.2 wt % and more preferably from 0.25 to 1 wt %.
  • the carbon is generally provided by the process control agent used during mechanical alloying to control inter-particle welding, as described below.
  • Dispersion strengthening in alloys of the present invention is provided by oxide- and carbide-based dispersoids which may be formed during the mechanical alloying or subsequent consolidation or both. Alternatively, they may be added as such to the powder.
  • dispersoid examples include Al 2 O 3 , AlOOH, Li 2 0, Li 3 AlO 4 , LiAlO 2 , LiAl 5 O 8 , Li 5 AlO 4 , Li 2 O 2 and A1 4 C 3 .
  • Other dispersoids may be used provided that they are stable in the Al-Li matrix at the temperature of service. Oxides of lithium are particularly suitable for use as dispersoid in alloys of the present invention, and,of these, Li 2 0 2 is preferred.
  • the dispersoid content is as low as possible consistent with the desired strength.
  • the dispersoid content may thus be up to 8% by volume and more preferably lies in the range from 3 to 5 vol. %.
  • the dispersoid should be'very fine, preferably having a particle size of about 0.02 microns, and should be uniformly dispersed throughout the alloy. It is believed that the fine grain size of alloys of this invention (about 0.1 microns) is, at least in part, responsible for their high room temperature strength.
  • the mechanical alloying process used to prepare the alloys of the present invention comprises the dry, high energy milling of aluminium and lithium powders in the presence of a grinding medium, e.g. balls, and a carbon- containing process control agent, so as to comminute the powder particles and, by a combination of repeated communi- tion and welding, to create new, dense composite particles containing fragments of the initial powder materials intimately associated and uniformly interdispersed.
  • the process control agent which serves to control interparticle welding, may for example be graphite or a volatilisable organic compound which may also contain oxygen. We prefer to use methanol,stearic acid, or graphite, but other organic acids, alcohols, aldehydes, ethers, or heptanes may be used.
  • the process control agent is added intermittently during milling, the amount used being calculated based in known manner on such factors as the ball-to-powder ratio, starting powder size, and mill temperature.
  • the milling is carried out under a blanket of argon or nitrogen to facilitate control of the oxygen content of the powder, as virtually the only sources of oxygen are the starting powders and the process control agent (if this contains oxygen).
  • the powder may be prepared in an attritor using a ball-to-powder weight ratio of from 15:1 to 60:1.
  • the dispersion strengthened mechanically alloyed powder is then degassed and consolidated at a temperature below its liquation temperature.
  • Degassing may be carried out at a temperature in the ranqe from 220° to 600°C.
  • Subsequent consolidation may also be carried out at a temperature in the range from 220 to 600°C, preferably at about 500 o C.
  • a separate compaction step may be employed.
  • the powder may be canned, degassed at 510°C, hot compacted and extruded at a temperature in the range from 315° to 510°C. It is believed that these preferred conditions produce alloys in which fine grain size, high dislocation density, fine uniform dispersion of oxides and carbides, and lithium in solid solution all contribute to strength.
  • alloys of the invention have good resistance to corrosion including stress corrosion cracking, and good thermal stability.
  • the strength of alloys according to the invention may be further increased by an age-hardening heat treatment.
  • This heat treatment consists of two steps; a solution treatment at a temperature not exceeding that used in the degassing or consolidation and an ageing treatment, between which the alloy is cooled.
  • the cooling may be in air, or by quenching, for example in water or oil.
  • the solution treatment is effected at the same temperature as the consolidation.
  • a suitable temperature range for both operations is from 400 to 540°C.
  • the solution treatment may be carried out for a length of time ranging from that sufficient to bring the alloy up to temperature (generally at least 0.5 hours) up to 4 hours.
  • the age-hardening may be effected at a temperature in the range from 95 to 260°C for a period of from 1 to 48 hours. More preferably, the age-hardening temperature range is from 120 to 230°C and the duration of the ageing is from 1 to 24 hours. It will be appreciated by those skilled in the art that for both solution treatment and age-hardening the time element bears an inverse relationship to the temperature.
  • Alloys of the present invention may also, of course, be used without age-hardening.
  • the strength of the alloys may be maximised by controlling their compositon very carefully to avoid excessive uncontrolled precipitation of the 0 phase (Al 3 Li) as this tends to render the alloys somewhat brittle and may impair their corrosion resistance.
  • Al 3 Li Al 3 Li
  • the lithium content preferably does not exceed 2.3% so as to minimise the risk of phase formation.
  • the Li in the system then comprises about 1.5 wt % in equilibrium solid solution and up to about 0.8 wt % in supersaturated solid solution.
  • composition range for alloys which are not to be age-hardened is from 1.7 to 2.3 wt % lithium, from 0.4 to 1.0 wt % oxygen and from 0.25 to 0.7 wt % carbon.
  • Specimens of two Al-Li alloys according to the invention were prepared from dispersion-strengthened, mechanically alloyed powders which had been ground in a high energy impact mill for 4 hours using a ball:powder ratio by weight of 40:1 under a blanket of argon in the presence of a process control agent.
  • the powders were canned, vacuum degassed for 3 hours and compacted at 510 C, then extruded to rod of diameter 1.6 cm at a temperature of 343°C.
  • compositions of alloys A and B are shown in Table I below.
  • Samples of alloys A and B were subjected to different heat treatments after extrusion and the effect of the heat treatments on the hardness of the alloys was determined.
  • the heat treatments began with a solution treatment of duration 0.5 hours at 510°C.
  • the specimens were quenched in water and then age-hardened at 177°C for various periods between O and 16 hours.
  • the age hardened alloys were air cooled and their hardnesses on the Rockwell B (R B ) scale were determined at room temperature.
  • Example I Samples of the two alloys A and B used in Example I were subjected to different heat treatments after extrusion and the effect of these heat treatments on their strength was determined. As in Example I, a solution treatment of duration 0.5 hours at the temperature previously used for degassing and consolidation, (in this case 510°C) was carried out. This was followed by a water quench and then an age hardening treatment at 177°C. Specimens of alloy A were age hardened for 1 hour whilst specimens of alloy B were age hardened for 4 hours. The alloys were air cooled and their tensile strengths were measured at room temperature.
  • heat treatment is beneficial for alloys containing more than about 2.0 wt % lithium in that the tensile properties can be improved.
  • the thermal stability of the alloys may also be improved by age-hardening. Ageing treatments at lower temperatures are expected to produce benefits in Al-Li alloys with lower lithium contents.
  • the mechanically alloyed powders were canned, vacuum degassed and compacted at 510 C and extruded to rod of diameter 1.6 cm at a temperature of 343°C or427°C.
  • the composition of each sample was analysed either as powder or as rod or both.
  • compositions of, and process details used for, the different alloys are shown in Table IV as is the Brinell hardness of the consolidated billets (Can BHN) at 500 and 3000 kg load. Alloys 13 and 14 were degassed for 4 hours and the other alloys were all degassed for 3 hours.
  • Alloys 1, 2, 5, 6, 7, 10, 11, 12, 13, 15, and 16 are according to the present invention. Of these alloys, particularly good properties are shown by alloys 1, 6, 7, 10, 11, 12, 15 and 16. All these alloys have a yield strength of at least 380 N/mm2 (tensile elongation between 2 and 13%) and a specific modulus of at least 2.89 x 10 6 m. It can be seen from Table IV that none of these alloys has a lithium content greater than 2.6 wt %. The deleterious effect of too much oxygen is shown by the results for alloy 4.
  • alloys of the invention which have a high specific modulus, (6, 7, 10, 11 and 12) have sufficiently high strength without magnesium.
  • the allowable magnesium content seems to be governed at least in part by the oxygen content.
  • Alloy 3 for example, has a magnesium content of 0.072 wt % and an oxygen content of 1.53 wt % and the ductility is poor. With higher amounts of Mg, (see Alloy 2) the effect is even more marked. The Mg content is therefore restricted to a maximum of 1.0 wt %.
  • alloys 10 and 11 of this invention showed excellent resistance to stress corrosion cracking even when loaded at the yield stress.
  • the electron diffraction pattern of a foil of alloy 1 and the X-ray diffraction pattern of extruded rod of alloy 2 were studied. Electron diffraction patterns using transmission electron microscopy and the X-ray diffraction data suggest that the dispersoid is Li 2 0 2 .
  • Transmission electron microscopy of a sample of alloy 1 showed a grain size of about 0.1 microns.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
EP19810303470 1980-07-31 1981-07-28 Alliages en aluminium durci par vieillissement Expired EP0045622B1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US06/174,182 US4532106A (en) 1980-07-31 1980-07-31 Mechanically alloyed dispersion strengthened aluminum-lithium alloy
US06/174,181 US4409038A (en) 1980-07-31 1980-07-31 Method of producing Al-Li alloys with improved properties and product
US174181 1980-07-31
US174182 1998-10-16

Publications (2)

Publication Number Publication Date
EP0045622A1 true EP0045622A1 (fr) 1982-02-10
EP0045622B1 EP0045622B1 (fr) 1984-12-05

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2549493A1 (fr) * 1983-07-21 1985-01-25 Cegedur Procede d'obtention a partir de poudre d'alliage d'aluminium a haute resistance de demi-produits files
EP0134403A1 (fr) * 1983-08-25 1985-03-20 Vereinigte Aluminium-Werke Aktiengesellschaft Fabrication par métallurgie des poudres d'un composé intermétallique lithium-aluminium et son utilisation
EP0180144A1 (fr) * 1984-10-23 1986-05-07 Inco Alloys International, Inc. Alliages d'aluminium renforcés par dispersion
EP0194700A2 (fr) * 1985-03-15 1986-09-17 Inco Alloys International, Inc. Alliages d'aluminium
EP0230123A1 (fr) * 1985-12-16 1987-07-29 Inco Alloys International, Inc. Formation d'alliages intermétalliques et de précurseurs d'alliages du type intermétallique pour des applications subséquentes d'alliage mécanique
EP0244949A1 (fr) * 1986-04-04 1987-11-11 Inco Alloys International, Inc. Préparation d'un alliage d'aluminium contenant un carbure stable par alliage mécanique
EP0130034B1 (fr) * 1983-06-24 1988-04-20 Inco Alloys International, Inc. Procédé de préparation de matériaux composites
DE3813224A1 (de) * 1988-04-20 1988-08-25 Krupp Gmbh Verfahren zur einstellung feinstkristalliner bis nanokristalliner strukturen in metall-metallmetalloid-pulvern
EP0295008A1 (fr) * 1987-06-09 1988-12-14 Alcan International Limited Alliages composites à base d'aluminium
WO1990002620A1 (fr) * 1988-09-12 1990-03-22 Allied-Signal Inc. Traitement thermique pour materiaux composites d'une matrice metallique a base de lithium/aluminium
CN116875839A (zh) * 2023-09-06 2023-10-13 山东伟盛铝业有限公司 一种铝锂合金型材及其制备方法

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2947068A (en) * 1958-04-18 1960-08-02 John S Nachtman Aluminum base powder products
DE1558491A1 (de) * 1967-04-05 1970-03-26 Ambarcumjan Sofja Mamikonovna Legierung auf Aluminiumgrundlage
GB1216513A (en) * 1967-01-16 1970-12-23 Atomenergikommissionen Improvements in and relating to dispersion strengthened aluminium products
DE1927500A1 (de) * 1969-05-30 1971-02-11 Max Planck Gesellschaft Verwendung lithiumhaltiger aushaertbarer Aluminiumlegierungen
US3591362A (en) * 1968-03-01 1971-07-06 Int Nickel Co Composite metal powder
US3740210A (en) * 1971-07-06 1973-06-19 Int Nickel Co Mechanically alloyed aluminum aluminum oxide
US3816080A (en) * 1971-07-06 1974-06-11 Int Nickel Co Mechanically-alloyed aluminum-aluminum oxide

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2947068A (en) * 1958-04-18 1960-08-02 John S Nachtman Aluminum base powder products
GB1216513A (en) * 1967-01-16 1970-12-23 Atomenergikommissionen Improvements in and relating to dispersion strengthened aluminium products
DE1558491A1 (de) * 1967-04-05 1970-03-26 Ambarcumjan Sofja Mamikonovna Legierung auf Aluminiumgrundlage
US3591362A (en) * 1968-03-01 1971-07-06 Int Nickel Co Composite metal powder
DE1927500A1 (de) * 1969-05-30 1971-02-11 Max Planck Gesellschaft Verwendung lithiumhaltiger aushaertbarer Aluminiumlegierungen
US3740210A (en) * 1971-07-06 1973-06-19 Int Nickel Co Mechanically alloyed aluminum aluminum oxide
US3816080A (en) * 1971-07-06 1974-06-11 Int Nickel Co Mechanically-alloyed aluminum-aluminum oxide

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Metal Progress, Vol. 113, March 1978, T.H. SANDERS "Aluminum-Lithium Alloys, Low Density and High Stiffness" *pages 32-37* *
Metallurgical Transactions A Vol. 10A, December 1979, D. WEBSTER: "Properties and Microstructure of Aluminum-Copper-Magnesium-Lithium Alloys" pages 1913-1912 *page 1913, left-hand column, lines 1-15, table I, page 1920, discussion, especially lines 4-23, 42-52* *

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0130034B1 (fr) * 1983-06-24 1988-04-20 Inco Alloys International, Inc. Procédé de préparation de matériaux composites
EP0133144A1 (fr) * 1983-07-21 1985-02-13 Cegedur Societe De Transformation De L'aluminium Pechiney Procédé d'obtention à partir de poudre d'alliage d'aluminium à haute résistance de demi-produits filés
FR2549493A1 (fr) * 1983-07-21 1985-01-25 Cegedur Procede d'obtention a partir de poudre d'alliage d'aluminium a haute resistance de demi-produits files
EP0134403A1 (fr) * 1983-08-25 1985-03-20 Vereinigte Aluminium-Werke Aktiengesellschaft Fabrication par métallurgie des poudres d'un composé intermétallique lithium-aluminium et son utilisation
EP0180144A1 (fr) * 1984-10-23 1986-05-07 Inco Alloys International, Inc. Alliages d'aluminium renforcés par dispersion
EP0194700A2 (fr) * 1985-03-15 1986-09-17 Inco Alloys International, Inc. Alliages d'aluminium
EP0194700A3 (fr) * 1985-03-15 1988-01-07 Inco Alloys International, Inc. Alliages d'aluminium
EP0230123A1 (fr) * 1985-12-16 1987-07-29 Inco Alloys International, Inc. Formation d'alliages intermétalliques et de précurseurs d'alliages du type intermétallique pour des applications subséquentes d'alliage mécanique
EP0244949A1 (fr) * 1986-04-04 1987-11-11 Inco Alloys International, Inc. Préparation d'un alliage d'aluminium contenant un carbure stable par alliage mécanique
EP0295008A1 (fr) * 1987-06-09 1988-12-14 Alcan International Limited Alliages composites à base d'aluminium
DE3813224A1 (de) * 1988-04-20 1988-08-25 Krupp Gmbh Verfahren zur einstellung feinstkristalliner bis nanokristalliner strukturen in metall-metallmetalloid-pulvern
WO1990002620A1 (fr) * 1988-09-12 1990-03-22 Allied-Signal Inc. Traitement thermique pour materiaux composites d'une matrice metallique a base de lithium/aluminium
CN116875839A (zh) * 2023-09-06 2023-10-13 山东伟盛铝业有限公司 一种铝锂合金型材及其制备方法
CN116875839B (zh) * 2023-09-06 2023-12-12 山东伟盛铝业有限公司 一种铝锂合金型材及其制备方法

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EP0045622B1 (fr) 1984-12-05
DE3167605D1 (en) 1985-01-17

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