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.

diagram: composition of an aluminium alloy

graph: uses of aluminium

photo: aluminium bicycle
photo: aluminium car body
photo: electricity pylons
photo: ring-pull can
photo: ladder

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