Magnesium became a technically important element during the 1920s. The raw material can be worked cost-favourably, and has a low specific gravity. On an identical component, the weight-saving compared to aluminium is 40 per cent, and compared to steel it is as much as 80 per cent. For this reason, magnesium is attractive in vehicle and aircraft construction.

Further advantages of magnesium are:

• Strength
• Easy to machine
• Good for welding
• Optimal material for casting

The biggest share of recycled magnesium is used in the aluminium and steel industry.

To improve corrosion characteristics, magnesium can be coated with chemical conversion layers or anodic oxidation layers. The porosity of these layers make them an excellent key for an additional protective paint coating.

http://en.wikipedia.org/wiki/Magnesium