The growth in the cost of aviation fuel in the 1970s was the driving force behind the development of lithium-based alloys that could replace the existing ones because they were lighter.
Their development was initially blocked by the technological difficulties inherent in production, due to the explosive reaction that these alloys in the liquid state have with water.
Today they are widely used in the aerospace industry, a sector in which it is willing to bear higher costs to have the lightest possible materials, given the industrial weight of this sector, whose numbers give it a strategic value for the aluminum industry.
In this context, the generation of aluminum-lithium alloys or, more precisely, a new generation of lithium alloys for which the compositions and the production process have been restyled is of particular importance.
Currently these alloys are the most used by designers, especially in the aviation industry, but also in different sectors, such as land transport and sports equipment.
The most used aluminum-lithium alloys refer to the Al-Cu-Li family, with the characteristic of having a copper weight concentration higher than that of lithium.
There are several advantages that make the use of lithium alloys interesting:
- the low density of lithium (which, for the same weight, decreases the density of the total volume of the alloy)
- a high elastic module
- good fatigue resistance
- good resistance to crack propagation
- good resistance to “stress corrosion” (even if anisotropic)
The main critical issues to be monitored are instead:
- low ductility
- danger of violent oxidation of lithium in the presence of moisture
- general increase in fragility due to high levels of Li.
Aluminum-lithium alloys therefore present themselves not only as a very important reality, but also as a possible future alternative in various sectors, given the experimentations and the attempt of new applications.