Anisotropy
Strength in the 45° direction can be noticeably lower than longitudinal strength. Check all directions in the specification, not just L.
Aluminium-lithium aerospace alloy
2090 Aluminium-Lithium Aerospace Sheet and Plate
2090 is a second-generation aluminium-lithium alloy that is about 8 % lighter and 10 % stiffer than 7075, with comparable strength in the T8 tempers. It is supplied as 2090-T83 sheet to AMS 4251 and 2090-T81 plate to AMS 4303 for weight-critical airframe parts. Metline sources 2090 sheet and plate to order for aerospace and defence buyers worldwide, with full mill certification.
- Alloy
- 2090 (Al-Cu-Li-Zr)
- Tempers
- T83 sheet, T81 plate
- Density
- 2.59 g/cm³
- Standards
- AMS 4251 · AMS 4303
Why aluminium-lithium, and where 2090 fits
Each 1 % of lithium added to aluminium reduces density by about 3 % and raises the elastic modulus by about 6 %. No other alloying element gives both effects, which is why aluminium-lithium alloys have been developed for aircraft since the 1950s.
2090 was introduced in the 1980s as a direct, lighter replacement for 7075-T6 in sheet and thin plate. With around 2.2 % lithium and 2.7 % copper, plus zirconium for grain control, it reaches high strength after solution treatment, controlled stretching and artificial ageing. The stretch before ageing is essential: it creates dislocations on which the strengthening T1 phase nucleates, which is why the useful tempers are all T8-type.
The second-generation alloys also showed weaknesses: strong anisotropy, low short-transverse toughness and ductility in thick sections, and a tendency to lose toughness after long exposure to warm temperatures. Third-generation alloys such as 2195, 2196, 2198 and 2050 reduce lithium content and add silver, magnesium or manganese to overcome these issues, and they now dominate new programmes. 2090 remains specified on existing drawings, in thin sheet applications and in defence and space hardware designed around it.
2090 chemical composition (wt %)
Registered limits for alloy 2090. The AMS titles give the nominal composition as 2.7Cu-2.2Li-0.12Zr.
| Element | Minimum | Maximum | Role |
|---|---|---|---|
| Copper (Cu) | 2.4 | 3.0 | Forms T1 (Al2CuLi) and θ′ strengthening phases |
| Lithium (Li) | 1.9 | 2.6 | Lowers density and raises stiffness; forms δ′ (Al3Li) |
| Zirconium (Zr) | 0.08 | 0.15 | Suppresses recrystallisation, keeps a fine grain structure |
| Magnesium (Mg) | — | 0.25 | Impurity / minor |
| Silicon (Si) | — | 0.10 | Impurity |
| Iron (Fe) | — | 0.12 | Impurity; kept low for toughness |
| Zinc (Zn) | — | 0.10 | Impurity |
| Titanium (Ti) | — | 0.15 | Grain refiner |
| Manganese, Chromium (each) | — | 0.05 | Impurities |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder | About 93.2 – 95.6 % |
Mechanical and physical properties
Published typical values for 2090 in the peak-aged T8 condition are about 550 MPa tensile strength, 520 MPa yield strength and 6 % elongation. Specified minimums in AMS 4251 and AMS 4303 are lower, vary with thickness, and are set separately for the longitudinal, long-transverse and 45° directions because of the alloy's anisotropy.
| Property | 2090-T83 sheet | 2090-T81 plate | 7075-T6 sheet (for comparison) |
|---|---|---|---|
| Specification | AMS 4251 (1.02 – 6.32 mm) | AMS 4303 | AMS 4045 / ASTM B209 |
| Typical tensile strength | about 530 – 550 MPa | slightly below T83 | 572 MPa |
| Typical yield strength | about 500 – 520 MPa | slightly below T83 | 503 MPa |
| Typical elongation | about 5 – 6 % | about 5 – 8 % | 11 % |
| Density | 2.59 g/cm³ | 2.59 g/cm³ | 2.81 g/cm³ |
| Modulus | about 76 GPa | about 76 GPa | 71.7 GPa |
Typical values compiled from Aluminum Association, ASM and producer data. Some supplier sheets list 2090 in an O temper with a strength of around 300 MPa; annealed 2090 is much softer than that, and O is not a normal delivery temper for aerospace use.
Physical properties of 2090
- Density
- 2.59 g/cm³ (about 8 % lower than 7075)
- Modulus of elasticity
- About 76 GPa (roughly 10 % higher than 7075)
- Thermal conductivity
- About 88 W/m·K
- Thermal expansion
- 23.6 µm/m·°C (20 – 100 °C)
- Melting range
- About 560 – 650 °C
Designing with 2090
Short-transverse properties
Thick plate has low through-thickness ductility and toughness. Avoid loading thick 2090 parts in the short-transverse direction.
Thermal exposure
Long service at raised temperatures can reduce toughness. Keep 2090 parts away from hot zones.
Joining
Riveting and bonding are normal. Fusion welding is possible with suitable filler but is rarely used for structure.
Machining
Machines like other 2xxx alloys. Segregate lithium-bearing chips: they must not be mixed with conventional aluminium scrap.
Galvanic contact
Isolate from carbon-fibre composites and steel fasteners with sealant and coatings, as for other aluminium alloys.
Forms, sizes and inspection
Supply range
- Sheet
- 2090-T83 to AMS 4251, about 1.0 – 6.3 mm
- Plate
- 2090-T81 to AMS 4303 in thin plate gauges
- Size
- Common mill sheet sizes such as 1250 × 2500 mm and cut blanks
- Inspection
- Tensile tests in specified directions, conductivity, dimensional and surface checks; ultrasonic inspection where required
- Certification
- EN 10204 3.1 certificate with chemistry, including lithium, and mechanical results
2090 is produced in campaigns by a small number of mills, so it is ordered rather than held as general stock.
Typical uses
- Floor beams and bulkhead stiffeners where stiffness and weight govern
- Wing leading and trailing edge skins
- Fuselage bulkhead webs and frames in thin gauges
- Cryogenic and launch vehicle structures designed around Al-Li
- Defence airframes and missile bodies needing low weight
How to order 2090 sheet and plate
- SpecifyProduct (sheet or plate), temper (T83 or T81), thickness, size, quantity, AMS 4251 or AMS 4303 revision, and any customer specification.
- Confirm the specificationWe check the order against the governing AMS, ASTM or EN document, confirm tempers, sizes, tolerances and any customer flow-down clauses, and quote on EXW, FOB, CIF or DAP terms.
- ProcessSheets and plates are cut, inspected and interleaved, with lithium-bearing material marked separately for traceability and recycling.
- DocumentEach lot ships with a mill test certificate to EN 10204 3.1 showing heat or lot number, chemical analysis and mechanical test results, plus any ultrasonic or other inspection reports called for on the order.
- Pack and shipMaterial is protected against moisture and handling damage, packed in seaworthy cases or on pallets, marked for traceability and shipped by sea or air.
References and standards
- SAE AMS 4251 – Aluminum Alloy Sheet 2.7Cu-2.2Li-0.12Zr (2090-T83)
- SAE AMS 4303 – Aluminum Alloy Plate 2.7Cu-2.2Li-0.12Zr (2090-T81)
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
- ASM Handbook Vol. 2 – Aluminum-Lithium Alloys
2090 aluminium-lithium (aluminum-lithium) sheet: FAQ
How much lighter is 2090 than 7075?
About 8 % by density (2.59 against 2.81 g/cm³). Because 2090 is also about 10 % stiffer, stiffness-critical parts can save more weight than the density difference suggests.
What do T83 and T81 mean for 2090?
Both are solution heat-treated, cold worked by stretching and artificially aged. T83 is the sheet temper in AMS 4251; T81 is the plate temper in AMS 4303.
Is 2090 still used?
Yes, on existing designs and in some defence and space hardware. New aircraft programmes mostly use third-generation Al-Li alloys such as 2050, 2196 and 2198.
Can 2090 be welded?
It can be fusion welded with suitable filler, but structural parts are normally riveted or bonded. Friction stir welding is used on some Al-Li structures.
Why must 2090 scrap be kept separate?
Lithium contaminates conventional aluminium scrap streams. Al-Li chips and offcuts are collected and recycled separately.
Need 2090 aluminium-lithium sheet or plate?
Send your specification, sizes and quantity. We will confirm availability and certification.
