Aluminium Alloys 2xxx and 7xxx: Lightweighting Aircraft and Vehicles

Wrought aluminium alloys are grouped by principal alloying element (1xxx pure, 2xxx Cu, 3xxx Mn, 5xxx Mg, 6xxx Mg+Si, 7xxx Zn). The heat-treatable 2xxx (Al-Cu) and 7xxx (Al-Zn-Mg-Cu) families provide the highest strengths (up to about 600 MPa) and are the backbone of aerospace structures.

Starke and Staley (1996) summarised how precipitation hardening governs properties: 2xxx alloys age-harden via S' (Al2CuMg) and theta' (Al2Cu); 7xxx alloys via eta'/eta (MgZn2). 2024 (high toughness) and 7075-T6 (high strength) are classics for wings and fuselage; 7050/7150 and 7085 improve toughness and exfoliation resistance for thick sections. Polmear (2006) updated the science, including dispersoid control and the newer Al-Li alloys. 6xxx alloys (6061, 6082) trade peak strength for corrosion resistance and extrudability and dominate automotive and structural profiles.

Selection note: 2xxx are less corrosion-resistant (clad for skin) while 7xxx need prudent ageing (T73/T76) to resist stress-corrosion cracking. JLHSteel stocks 1050/3003/5052/5083/6061/6063/7075 plate, sheet, extrusions and bar with EN 573 / ASTM B209 certificates.

References
1. Starke, E.A., Staley, J.T. (1996). Application of modern aluminum alloys to aircraft. Progress in Aerospace Sciences 32(2-3): 131-172. https://doi.org/10.1016/0376-0421(95)00010-2
2. Polmear, I.J. (2006). Light Alloys: From Traditional Alloys to Nanocrystals. Butterworth-Heinemann.
3. ASM Handbook, Volume 2: Nonferrous Alloys and Special-Purpose Materials (1990). ASM International.