Approximately 15 million tonnes of aluminium alloys use pure magnesium as an alloying element. 80% of the world's production of aluminium wrought alloys and 60% of the world's production of cast alloys use magnesium as an alloying addition.
For the former category, additions of 0.1% - 4.4% magnesium improve the formability and weldability of aluminium alloys. For the latter category, additions of 0.3% - 1.5% magnesium improve the corrosion resistance and tensile properties of aluminium alloys following heat treatment.
The magnesium containing aluminium alloys are used in 3 principal industries:
Packaging accounts for 50% of the demand for magnesium in the aluminium sector, consuming approximately 70,000 tonnes per annum. The principal use of magnesium containing alloys in this sector is for beverage cans. Other applications include aluminium foils, food cans and aerosol canisters.
The automobile industry consumes 35% or 50,000 tonnes of the magnesium being supplied to the aluminium industry. Wrought alloys containing magnesium are used primarily in the production of automotive sheet, while cast alloys containing magnesium are used in the production of cylinder heads, pistons and engine blocks.
Structural extrusion profiles in the construction industry account for the remaining 15% of the demand for magnesium in the aluminium alloying sector, totaling some 20,000 tonnes.