Aluminum is available in a series of standard alloys. Their differing chemical compositions result in unique mechanical and physical properties. "Hard" alloys are frequently used in aerospace and structural applications. "Soft" alloys are the most common.

The major alloying elements - which include silicon, iron, magnesium and copper - impart varying physical and performance properties such as corrosion resistance, finishing response, weldability, machinability and formability. Alloys also vary by temper, which determines their yield tensile strength.

Extrusion-grade aluminum comes mainly in the following alloy types:

1000 series – Al

A non-heat treatable alloy often chosen in products where thermal and electrical conductivity are desired. They have low strength.

6000 series – Al + Mg + Si

A heat-treatable alloy that has good extrudability. They have medium to high strength, are easy to weld and offer good resistance to corrosion, even in marine environments. The bulk of extruded material for load bearing construction is made from these qualities.

7000 series – Al + Zn + Mg

A heat-treatable alloy with the highest strength. They have good weldability and obtain lower reduction of strength in heat affected zones than the 6000 series. Their corrosion resistance and formability are not as good as the 6000 series (this can be improved by adding small amounts of Zr, Cr or Mn). Typical applications are automotive parts, aircraft containers, bicycles, etc