Why Aluminium Alloys Have So Many Names, and What They Mean

Pure aluminium is too soft to be structurally useful on its own, and almost everything people actually mean when they say “aluminium” is really a specific, engineered alloy.

Aluminium (FCC) · FCC unit cell · a = 4.050 ÅThe same face-centred cubic structure as copper, which is why aluminium is similarly ductile. Alloying, not the base lattice, is what gives it real strength.Drag to rotate · scroll to zoom

What the 4-digit alloy codes actually encode

1100-H14 (pure Al)

117 MPa yield

3003-H14 (Al-Mn)

145 MPa yield

5052-H32 (Al-Mg)

193 MPa yield

6061-T6 (Al-Mg-Si)

276 MPa yield

2024-T3 (Al-Cu)

345 MPa yield

7075-T6 (Al-Zn-Mg-Cu)

503 MPa yield

Yield strength by alloy family. The first digit of the alloy designation names the main alloying element; 7075-T6, strong enough for aircraft structure, is over four times stronger than commercially pure aluminium.

The strongest alloys (2xxx, 6xxx, 7xxx) rely on precipitation hardening: a fine dispersion of second-phase particles forms during heat treatment and blocks dislocation motion, the same general mechanism described more fully on cobalt’s mechanics page for gamma-prime in nickel superalloys. The gain from this is real and quantifiable, though it is usually judged relative to weight, not strength alone:

\frac{\sigma_y}{\rho}

Specific strength: yield strength divided by density. Aluminium's own density (2.70 g/cm³) is already roughly a third of steel's, so even a moderately strong aluminium alloy can match or beat a stronger but much denser steel on this ratio, which is the entire reason aerospace and automotive engineers reach for it.

Why this matters for supply chain resilience research

Aluminium’s usefulness is distributed across dozens of distinct alloy formulations rather than one material, each serving a different structural role, foil-grade pure metal, marine-grade Al-Mg, aircraft-grade Al-Zn, so a supply disruption to a specific alloying element (manganese, magnesium, zinc, copper, each covered on its own page on this site) propagates unevenly across aluminium’s own end uses rather than affecting “aluminium demand” as one undifferentiated category.

Sources: alloy compositions and strength values are standard published specifications (Aluminum Association, ASM Handbook); lattice parameter is a standard crystallographic value.