Aluminium is the most widely used non-ferrous metal and the second most used metal overall after steel. It combines a unique set of physical, chemical, and mechanical properties that make it indispensable across virtually every major industrial sector.
Basic Identification
| Property |
Value |
| Appearance |
Silvery-white, lustrous |
| Chemical symbol |
Al |
| Atomic number |
13 |
| Category |
Light Metal; Non-Ferrous Metal |
| Natural occurrence |
Never found as free metal in nature; occurs as oxides and silicates |
Physical & Chemical Properties
| Property |
Value |
| Density |
2.70 g/cm³ |
| Melting point |
660.3°C |
| Boiling point |
2,519°C |
| Hardness (Mohs) |
2.5–3.0 |
| Electrical conductivity |
~37.7 × 10⁶ S/m (~61% of copper) |
| Thermal conductivity |
205 W·m⁻¹·K⁻¹ |
| Tensile strength (pure) |
~90 MPa |
| Tensile strength (alloyed) |
200–700 MPa |
| Crystal structure |
Face-centred cubic (FCC) |
Key Characteristics
Aluminium owes its commercial dominance to an exceptional combination of properties:
- Low density — approximately one-third the density of steel, enabling significant weight savings in structural applications
- Corrosion resistance — a thin, self-healing aluminium oxide (Al₂O₃) passivation layer forms instantly on any exposed surface, providing excellent resistance to atmospheric and aqueous corrosion
- High electrical conductivity — the preferred conductor for high-voltage overhead power transmission lines where weight is critical
- Thermal conductivity — excellent heat dissipation properties used in heat exchangers and electronics cooling
- Recyclability — can be recycled indefinitely without loss of properties; recycling requires only ~5% of the energy needed for primary production
- Non-magnetic — valuable in electronics, medical equipment, and applications requiring magnetic neutrality
- Non-toxic — safe for food and pharmaceutical contact applications
Production
Primary aluminium is produced exclusively via the Hall–Héroult electrolytic process, in which alumina (Al₂O₃) — derived from bauxite ore via the Bayer Process — is dissolved in molten cryolite (Na₃AlF₆) at approximately 960°C and subjected to a high direct electrical current. Aluminium deposits at the carbon cathode while oxygen is released at the carbon anode. The production chain therefore runs:
Bauxite → Alumina (Bayer Process) → Aluminium (Hall–Héroult Process)
Approximately 4–5 tonnes of bauxite yield 2 tonnes of alumina, which in turn produces 1 tonne of primary aluminium. Primary aluminium production is highly energy-intensive, consuming approximately 13–15 MWh of electricity per tonne.
Commercial Forms
Aluminium is traded and supplied in a range of physical forms:
- Primary aluminium ingots — standard LME-traded form (P1020 grade)
- Billets — cylindrical feedstock for extrusion
- Slabs — flat feedstock for rolling into sheet and plate
- Wire rod — feedstock for electrical conductor wire
- Foundry alloys — liquid or solid alloys for casting
- Powder & flake — for pyrotechnics, coatings, and powder metallurgy
Alloying & Grades
Pure aluminium (>99% Al) has limited mechanical strength and is used primarily in electrical conductors and foil. For structural applications, aluminium is alloyed with other elements, organised into standardised series:
| Series |
Principal Alloying Element |
Typical Applications |
| 1xxx |
None (>99% Al) |
Electrical conductors, foil, chemical equipment |
| 2xxx |
Copper |
Aerospace structures, aircraft skin |
| 3xxx |
Manganese |
Beverage cans, cooking utensils |
| 4xxx |
Silicon |
Welding wire, brazing alloys |
| 5xxx |
Magnesium |
Marine structures, automotive panels |
| 6xxx |
Magnesium + Silicon |
Architectural extrusions, structural profiles |
| 7xxx |
Zinc |
High-strength aerospace components |
| 8xxx |
Other elements (Li, Fe) |
Lithium-aluminium aerospace alloys, foil |
Applications
Aluminium's versatility makes it present across virtually every sector of the economy:
- Transport — automotive body panels, aircraft fuselages, railway carriages, ship superstructures
- Packaging — beverage cans, food foil, pharmaceutical blister packs
- Construction — window frames, curtain walling, roofing, structural profiles
- Electrical — overhead transmission lines (ACSR and AAAC cables), busbars, transformer windings
- Machinery & engineering — heat exchangers, pressure vessels, pistons
- Consumer goods — electronics casings, bicycles, sports equipment
- Defence & aerospace — structural airframes, armour plate, missile components
World Production & Trade
Global primary aluminium production exceeds 70 million tonnes per year, with China accounting for approximately 55–60% of global output. Aluminium is one of the most actively traded industrial commodities globally, with primary aluminium (P1020 grade) traded on the London Metal Exchange (LME) and the Shanghai Futures Exchange (SHFE). The leading producing countries outside China include India, Russia, Canada, the UAE, and Australia.
Sustainability & Recycling
Aluminium is one of the most sustainable industrial metals. Approximately 75% of all aluminium ever produced remains in active use today, a testament to its recyclability. Secondary (recycled) aluminium accounts for roughly one-third of global supply and requires only ~5% of the energy of primary production, making recycling a critical component of the aluminium industry's decarbonisation strategy.
References
- Wikipedia. Aluminium (Page version: Feb 24, 2026)
- Royal Chemical Society. Aluminium (Accessed Feb 24,2026)
- AZoM. (May 17, 2020) Aluminium properties, production and applications: An introduction
- AZoM — AZO Materials (May 17, 2005). Aluminium: Specifications, properties, classifications and classes
- Advanced Refractory Metals. Top 10 Properties of Aluminium and Its Applications (Accessed Feb 24,2026)
- Righton Blackburns (Feb 24, 2021). Properties and applications of aluminium
- London Metal Exchange (LME). LME Aluminium (Accessed Feb 24,2026)
- International Aluminium Institute (Apr 11, 2024). Primary aluminium production statistics
- Home A., Reuters. (Sep 19, 2025). Aluminium's years of plenty are drawing to a close
- Wikipedia. LME Aluminium (Page version: Feb 22, 2026)