Al-Li alloys

Aluminium-lithium alloys are a separate class of alloys characterised by valuable combination of properties:

  • lower density
  • higher Young's modulus
  • relatively high mechanical properties
  • corrosion resistance.

There are at present about 20 Russian wrought alloy grades. Developed for different purposes, they have different physical, mechanical, corrosive, technological and operational properties.

For instance, density of Al-Li alloys is in the range of 2,47 — 2,55 g/cm3 against 2,75 – 2,80 for traditional alloys of similar purpose, and Young's modulus is 75 – 80 GPa against 70 – 72 GPa

The processing technology makes Al-Li alloys somewhat more expensive than traditional aluminium alloys. This is, however, justified by their areas of use. Al-Li alloys are widely used in aviation and aerospace engineering. Using Al-Li alloys allows to reduce the weight of flight units, thus leading to fuel economy, increased carrying capacity and enhancement of other characteristics.

Widely used by the Russian aviation industry as sheet, plate, forgings etc, the following aircraft can be cited as examples of Al-Li alloys usage:

  • carrier-based attack Yak-38
  • passenger jets Yak-42, Tu-204
  • helicopter Mi-26Т
  • fighters Su-27, MiG-29
  • amphibious aircraft Be-200.

Al-Li alloy 1421 was used as forgings for the bodies of Makeyev Rocket Design Bureau's sea-based missiles. Alloy 1460 was used for liquid oxygen tanks (4500 mm diameter, 4000 mm height) of McDonnell Douglas's Delta rocket used for communication satellite launch to orbit.

Price is a factor limiting use of these alloys on a wider scale. In professional sport, however, seconds can be more precious than alloy.

SMWE has developed and mastered the technology of forging automobile wheels from Al-Li. Testing of the wheel demonstrated its advantages over wheels made from traditional aluminium alloys. At given dimensions, Al-Li exhibited properties 8-13% higher. Calculations show that at the same level of operational characteristics, 20-25% weight reduction is possible for Al-Li wheel.