Aluminum-lithium alloy

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Aluminum-lithium alloys are aluminum alloys that have improved properties through the addition of lithium . Above all, the density of an alloy can be reduced in this way, since the density of the alloy decreases by 3% with every mass percent lithium used. In addition, the modulus of elasticity increases .

In addition to lithium, other elements are usually added to these alloys, such as copper , manganese , magnesium , silver , zirconium or scandium . In particular, the copper content can be significantly higher than the lithium content (2xxx alloys).

Aluminum-lithium alloys are used in aircraft, spacecraft and rockets, but also in vehicle construction. So z. B. the outer tank of the space shuttle and parts of the passenger aircraft Boeing B777 , Airbus A350 and Airbus A380 are made of these alloys.

The first generation of aluminum-lithium alloys - between around 1950 and 1990 - was affected by a high tendency to corrosion , low ductility ( sliding band formation due to δ'- precipitates ) and low temperature resistance . These problems have been addressed in the second generation alloys with a reduced lithium content.

In the USSR such alloys were Moscow Aviation - Technology -Institut (MATI) developed what Olga Grushko Yevgenyevna 1999 the State Prize of the Russian Federation received.

In the current third generation, the mechanical properties, apart from toughness and vibration behavior at high loads, are now uncritical. However, due to the high tendency of lithium to oxidize, special protective devices must be provided in the foundry .

Examples of aluminum-lithium alloys

  • AA 2090: 2.7% Cu + 2.2% Li + 0.4% Ag + 0.12% Zr + balance aluminum (1st generation)
  • AA 2091: 2.1% Cu + 2.0% Li + 0.10% Zr + remainder aluminum (1st generation)
  • AA 8090: 2.45% Li + 0.12% Zr + 1.3% Cu + 0.95% Mg + remainder aluminum (1st generation)
  • Weldalite 049: 5.4% Cu + 1.3% Li + 0.4% Ag + 0.4% Mg + 0.14% Zr + rest of aluminum (2nd generation)
  • AA 2196: 3% Cu + 1.4–2% Li + 0.5% Mg + 0.4% Ag + 0.35% Mn + 0.1% Zr + remainder aluminum (3rd generation)

(All data in percent by mass )

See also

Individual evidence

  1. Amit Joshi: LITHIUM ALUMINUM ALLOYS - The New Generation Aerospace Alloys ( Memento of the original from September 28, 2007 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 180 kB), accessed on June 11, 2013. @1@ 2Template: Webachiv / IABot / www.metalwebnews.com
  2. bernd-leitenberger.de: Space Shuttle Booster and the Tank , accessed on June 11, 2013.
  3. NASA, Super Lightweight External Tank (PDF; 135 kB)
  4. ^ Flake C. Campbell: Elements of metallurgy and engineering alloys . 2008, ISBN 978-0-87170-867-0 ( page 497 in the Google book search).
  5. Указ Президента Российской Федерации от 29.09.1999 г. № 1307 (accessed May 31, 2020).
  6. International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys ( Memento of December 14, 2012 in the Internet Archive ) (PDF; 393 kB)