Cast Magnesium

Magnesium is very abundantly available, for example in sea water. The extracting process however takes a large amount of energy: 72 MJ/kg Mg, which makes it relatively expensive. Magnesium has a density even lower than Al. However also the Young's modulus is lower than that of Al, hence stiffness must be achieved by design. Mg is not covered by a protective oxide layer, but oxidation rates are normally low. In wet environments protection is necessary (anodising, coating). Strength can only be enhanced by alloying. Castability of Mg is good, and its machinability is excellent: it is fast and offers a high quality. For that reason castings of Mg and alloys represent about 85% of the Mg applications.