Aluminum-Lithium Alloys: Part One


Aluminum alloys containing lithium are under much scrutiny to perform with expectations that they will improve weight and stiffness critical application even against other aluminum alloys and even carbon-fiber composites.
Specific benefits of Al-Li alloys are a reduced density and an increased modulus of elasticity with an increase in the specific modulus of 26% compared to alloy 7075-T651.

In recent years, the family of lithium containing aluminum alloys has received much attention because it offers the promise of substantial specific strength and specific stiffness advantages over other commercial 2XXX- and 7XXX-series aluminum alloys and carbon-fiber composites. This advantage makes them an ideal candidate for weight-critical and stiffness-critical structures for military, space and commercial applications.

Most high-strength aluminum alloys used in aircraft structures are mechanically fastened, which has the drawbacks of slow assembly and limitations in joining thin sections. Fusion welding of lightweight aluminum-lithium alloys has been evaluated by several investigators and has resulted in various degrees of success. However, there exists a critical need to develop new joining methods in order to extend the range of applications for these alloys and to improve the overall performance, durability, damage tolerance and life of safety-critical components and structures. Furthermore, new joining methods could facilitate use of these alloys in marine hardware, lightweight pressure vessels and lightweight armored vehicles.

Magnesium and lithium are the only two elemental additions which, when added to aluminum, have the potential ability to decrease its density. Beryllium also decreases the density of aluminum but it is extremely toxic and is a health hazard. Lithium is one of the few elements with substantial solubility in aluminum (4.2 wt % at 600°C/1112°F in a binary aluminum lithium alloy).

The potential for aluminum alloy density reduction through lithium additions is evident by comparing its atomic weight (6.94) with that of aluminum (26.98). Lithium additions to aluminum also cause a significant increase in elastic modulus. Each 1% lithium addition of aluminum, up to 4 wt-% lithium, decreases the density by 3%, and increases the elastic modulus by 6%. The specific modulus (modulus of elasticity by weight) of an alloy with 2.8 wt-% lithium is 21% higher than that of aluminum alloy 2024-T351 and 26% higher than that of aluminum alloy 7075-T651.

The higher specific modulus reduces the rate of fatigue crack growth. The decrease in density is far more effective in reducing structural weight than improved strength, modulus, toughness or fatigue resistance. For example, in an aluminum alloy having 3 wt-% lithium, structural weight savings of 10% on affected structures could be realized by direct substitution, and over 16% by design modification based on improved mechanical properties.


Li is the lightest metallic element and each 1% of Li reduces an alloy density by about 3% and increases modulus by about 6%

  • 7-10% Lower density.
  • 10-15% Higher Modulus.
  • Excellent fatigue and cryogenic toughness properties.
  • Higher stiffness.
  • Superior fatigue crack growth resistance.
  • Reduced ductility.
  • Low fracture toughness.
  • Ease of fabrication using conventional equipment and methods.
  • Some operations that generate molten metal, such as flame cutting and welding, are hazardous because of the possibility of explosion if moisture is present.
  • These alloys are typically solution-heat-treated and aged in conventional furnace equipment.


Tendency to oxidize at elevated temperatures, leading to decreases in

  • Micro-hardness
  • electrical resistivity
  • precipitate density (material softens)


1) Aircraft parts such as leading and trailing edges, access covers, seat tracks and wing skins.
2) Military Applications: Certain types of military aircrafts parts like main wing box, center fuselage, control surfaces are made by Al-Li alloys. Al-Li alloys are used as a substitute for conventional Al alloys in helicopters, rockets and satellite systems.
3) Space Applications: Of all the benefits offered, by the use of Al-Li alloys, weight savings is the most critical in space applications. Al-Li alloy is a candidate material for the cryogenic tankage of booster systems. These alloys are used in cryogenic applications for example, liquid oxygen and hydrogen fuel tanks for aerospace vehicles.

Table 1: Physical properties of Al-Li alloys

기술 자료 검색

검색할 어구를 입력하십시오:

검색 범위



Total Materia는 다양한 나라와 규격에 따른 수천개의 알루미늄 재질에 대한 정보를 포함하고 있습니다.

재질의 화학적 조성, 기계적 특성, 물리적 특성, 고급 물성 데이터 등의 전체적인 특성 정보들을 어디서든 검토하실 수 있습니다.

고급 검색을 이용하여, 검색 조건의 재질 리스트에서 '알루미늄'을 선택합니다. 검색 범위 좀 더 줄이기를 원하신다면 국가/규격과 같은 다른 조건을 지정할 수 있습니다.

검색 버튼을 클릭합니다.

선택된 정보에 부합하는 일련의 재질이 검색됩니다.

결과 리스트에서 재질을 선택하시면, 일련의 규격 사양 소그룹이 나타납니다.

여기에서 선택한 재질의 특정 특성 데이터를 검토하실 수도 있고, 강력한 상호 참조 표를 이용하여 유사 재질이나 등가 재질을 검토하는 것 또한 가능합니다.

자세한 특성 데이터를 보시려면 특성 데이터 링크를 클릭하세요.

Total Materia 데이터베이스를 사용해 보실 수 있는 기회가 있습니다. 저희는 Total Materia 무료 체험을 통해 150,000명 이상의 사용자가 이용하고 있는 커뮤니티로 귀하를 초대합니다.