Aluminium: Uses

Pure aluminium is not often used as it has poor mechanical properties. It is usually alloyed with other metals or silicon. The various registered alloys are identified using a 4 digit numbering system, with each "series" referring to a particular combination of elements.

Series	Additional Content	Comments
1000	Minimum 99% Aluminium (+ Fe & Si)	Quite brittle
2000	Copper	Similar strength to mild steel
3000	Manganese
4000	Silicon
5000	Magnesium	Good for welding, very resistant to corrosion
6000	Magnesium - Copper
7000	ZInc - Magnesium - Copper	Very high strength
8000	Miscellaneous alloys	For example Aluminium - Lithium

The range of uses for aluminium reflect its properties, in particular its low density, resistance to corrosion and electrical conductivity.
Aluminium's resistance to corrosion results from the formation of a protective layer of oxide, which remains stable as long as the pH range is between 4.5 and 8.5. Outside this range it will dissolve. When aluminium is used for food packaging (carbonated drinks, for example) an additional polymer layer may be added to prevent the contents reacting with the aluminium oxide.