2099-T83 Aluminum
A third-generation Al-Cu-Li alloy, for structural extrusions
Typical values for the temper in the title
2099 is a third-generation aluminum-lithium alloy. Lithium is the lightest metal, and each percent of lithium lowers density by about 3% and raises the modulus by about 6%. so Al-Li gives lighter, stiffer parts than conventional 2000- and 7000-series alloys.
It contains relatively much lithium (about 1.8%), so it is one of the lightest in the family. It is supplied mainly as extrusions, for floor beams and stringers in aircraft.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | 517 MPa | |
| Yield strength Rp0.2 | 483 MPa | |
| Elongation A | 10% | |
| Hardness | 145 HB | |
| Modulus of elasticity E | 79 GPa | |
| Density ρ | 2.63 g/cm³ | |
| Machinability | 25% | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cu copper | about 2.7 (nominal) | strengthening |
| Li lithium | about 1.8 (nominal) | lowers density and raises modulus |
| Zn zinc | about 0.7 (nominal) | strengthening |
| Mg magnesium | about 0.3 (nominal) | |
| Mn manganese | about 0.3 (nominal) | |
| Zr zirconium | about 0.09 (nominal) | controls the grains |
| Al aluminum | balance |
Common tempers
Al-Li alloys are supplied in T8 tempers, which include cold work before aging.
| Temper | Properties | When to choose it |
|---|---|---|
| T83 | Rm ≈ 517 MPa, Rp0.2 ≈ 483 MPa (database value) | extrusions |
Applications
- Aircraft floor beams
- Stringers and stiffening profiles
- Light structural extrusions
- Inner fuselage structures
- Replacing 7xxx extrusions
Fabrication
Machining
Machines reasonably, but follow the producer's guidelines.
Welding
Fusion welding is not recommended. Friction stir welding (FSW) is possible.
Recycling
Al-Li chips and scrap must be collected separately from ordinary aluminum: lithium harms the quality of other alloys.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| 2196-T8511 | 550 / 510 MPa | Not recommended | another Al-Li for extrusions · material page |
| 7075-T6 | 503–572 / 434–503 MPa | Not recommended — FSW | conventional extrusions, heavier · material page |
| 2055 Al-Li Gen3 | 593 / 559 MPa | Not recommended | a stronger Al-Li · material page |
Common mistakes
Mixing Al-Li chips with ordinary aluminum
Lithium contaminates the recycling stream. Keep them separate.
Replacing a conventional alloy with Al-Li without recalculating
Modulus and density differ, and properties depend on direction. The design must be redone.
Looking for it in ordinary stock
These are aerospace alloys supplied to producer and customer specifications, not off-the-shelf products.
Equivalents, standards and supply
| ASTM | 2099 |
|---|---|
| Standards | AMS and aerospace manufacturer specifications |
| Forms | rod · extrusion |
| Producers | Alcoa (proprietary) |
Learn more
Values are typical and for comparison only. For design, rely on the standard and on the mill certificate. Sources: Aluminum Association (composition), ASM and MatWeb data sheets, and the METAL HUB materials database.
Updated: October 31, 2026