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Aluminium-lithium alloy (7132 views - Material Database)

Aluminium–lithium alloys (Al-Li) are a series of alloys of aluminium and lithium, often also including copper and zirconium. Since lithium is the least dense elemental metal, these alloys are significantly less dense than aluminium. Commercial Al–Li alloys contain up to 2.45% by weight of lithium.
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Aluminium-lithium alloy

Aluminium-lithium alloy

Aluminium–lithium alloys (Al-Li) are a series of alloys of aluminium and lithium, often also including copper and zirconium. Since lithium is the least dense elemental metal, these alloys are significantly less dense than aluminium. Commercial Al–Li alloys contain up to 2.45% by weight of lithium.[1]

Crystal structure

Alloying with lithium reduces structural mass by three effects:

  • Displacement—a lithium atom is lighter than an aluminium atom; each lithium atom then displaces one aluminium atom from the crystal lattice while maintaining the lattice structure. Every 1% by weight of lithium added to aluminium reduces the density of the resulting alloy by 3% and increases the stiffness by 5%.[1] This effect works up to the solubility limit of lithium in aluminium, which is 4.2%.
  • Strain hardening—Introducing another type of atom into the crystal strains the lattice, which helps block dislocations. The resulting material is thus stronger, which allows less of it to be used.[citation needed]
  • Precipitation hardening—When properly aged, lithium forms a metastable Al3Li phase (δ') with a coherent crystal structure.[2] These precipitates strengthen the metal by impeding dislocation motion during deformation. The precipitates are not stable however and care must be taken to prevent overaging with the formation of the stable AlLi (β) phase.[3] This also produces precipitate free zones (PFZs) typically at grain boundaries and can reduce the corrosion resistance of the alloy.[4]

The crystal structure for Al3Li and Al–Li, while based on the FCC crystal system, are very different. Al3Li shows almost the same size lattice structure as pure aluminium except lithium atoms are present in the corners of the unit cell. The Al3Li structure is known as the AuCu3, L12, or Pm3m and has a lattice parameter of 4.01 Å.[3] The Al–Li structure is known as the NaTl, B32, or Fd3m structure which is made of both lithium and aluminium assuming diamond structures and has a lattice parameter of 6.37 Å. The interatomic spacing for AlLi (3.19 Å) is smaller than either pure lithium or aluminium.[5]


Al–Li alloys are primarily of interest to the aerospace industry due to the weight advantage they provide. They are currently used in a few commercial jetliner airframes, the fuel and oxidizer tanks in the SpaceX Falcon 9 launch vehicle, Formula One brake calipers, and the AgustaWestland EH101 helicopter.[6]

The third and final version of the US Space Shuttle's external tank was principally made of Al-Li 2195 alloy.[7] In addition, Al–Li alloys are also used in the Centaur Forward Adapter in the Atlas V rocket,[8] in the Orion Spacecraft, and were to be used in the planned Ares I and Ares V rockets (part of the cancelled Constellation program).

Al-Li alloys are generally joined by friction stir welding. Some Al–Li alloys, such as Weldalite 049, can be welded conventionally; however, this property comes at the price of density; Weldalite 049 has about the same density as 2024 aluminium and 5% higher elastic modulus.[citation needed]

Although Aluminum-Lithium alloys are generally superior to Aluminum-Copper or Aluminum-Zinc alloys in ultimate strength to weight ratio, their poor fatigue strength under compression remains a problem which is only partially solved as of 2016.[9][10] Also, high costs (around 3 times or more conventional Aluminum alloys), poor corrosion resistance and strong anisotropy of mechanical properties of rolled Aluminum-Lithium products has resulted in the paucity of the applications.

On single-aisle airliners, Arconic (ex Alcoa) claims up to 10% weight reduction compared to composites leading to up to 20% better fuel economy, at a lower cost than titanium or composites. Al-Li is used on on the Airbus A380 and A350, Boeing 787 and Bombardier CSeries airliners, and on Gulfstream G650 and Bombardier Global 7000/8000 business jets.[11]

List of Aluminium-lithium alloys

Production sites

Key world producers of Aluminium-lithium alloy products are Alcoa, Constellium and Kamensk-Uralsky Metallurgical Works.

  • Alcoa Technical Center (Pennsylvania)
  • Alcoa Lafayette (Indiana); capacity 20,000 metric tons of aluminum lithium and capable of casting round and rectangular ingot for rolled, extruded and forged applications
  • Alcoa Kitts Green (United Kingdom)
  • Rio Tinto Alcan Dubuc Plant (Canada); capacity 30,000 metric tons
  • Constellium Issoire (Puy-de-Dôme)
  • Kamensk-Uralsky Metallurgical Works (KUMZ)
  • Aleris (Koblenz, Germany)
  • FMC
  • Southwest Aluminium

See also

Arsenical copper玻璃Mercury塑料Plexiglas不鏽鋼钢结构鋁鎳鈷合金Birmabright杜拉鋁HiduminiumHydronaliumItalma镁铝合金鋁合金Y alloy伍德合金Rose's metalChromium hydrideNichromeMegalliumStellite維塔立合金Beryllium copperBillon (alloy)黃銅Calamine brassChinese silverDutch metalGilding metalMuntz metalPinchbeck (alloy)Tombac青铜Aluminium bronzeArsenical bronzeBell metalFlorentine bronzeGlucydurGuanín (bronze)GunmetalPhosphor bronzeOrmoluSpeculum metal康銅氢化亚铜Copper–tungstenCorinthian bronzeCunife白铜Cymbal alloysDevarda's alloy琥珀金HepatizonManganinMelchior (alloy)Nickel silverMolybdochalkos北歐金ShakudōTumbagaAlGaGalfenolGalinstan白金 (合金)銠金礦Crown goldElinvarField's metalFernicoFerroalloyFerroceriumFerrochromeFerromanganeseFerromolybdenumFerrosiliconFerrotitaniumFerrouranium不變鋼铸铁Iron–hydrogen alloy生鐵Kanthal (alloy)KovarStaballoySpiegeleisenBulat steelCrucible steel41xx steel大馬士革鋼Mangalloy高速鋼Mushet steel马氏体时效钢High-strength low-alloy steelReynolds 531电工钢Spring steelAL-6XNCelestriumAlloy 20Marine grade stainless马氏体不锈钢Sanicro 28Surgical stainless steelZeron 100Silver steelTool steel耐候钢烏茲鋼銲料TerneType metalElektron (alloy)汞齊Magnox (alloy)AlumelBrightrayChromelHaynes International英高鎳合金MonelNicrosilNisilNickel titaniumΜ合金透磁合金超導磁率合金Nickel hydridePlutonium–gallium alloy钠钾合金MischmetalTerfenol-DPseudo palladiumScandium hydride釤鈷磁鐵Argentium sterling silverBritannia silverDoré bullionGoloidPlatinum sterlingShibuichiSterling silverTibetan silverTi Beta-C.Titanium alloy氢化钛Gum metalTitanium gold氮化钛巴氏合金Britannia metalPewterQueen's metalWhite metal氢化铀ZamakZirconium hydride甲烷Mezzanine原子

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