Magnesium automobile wheel

In the presence of O2, magnesium metal is protected by a thin coating of water-insoluble MgO. Thus, even though Mg is high in the activity series (Section 4.4), it Can be incorporated into lightweight stmctural alloys used in, for example, automobile wheels. The heavier alkaline earth metals (Ca, Sr, and Ba) are even more reactive toward nonmetals than is magnesium. 

Magnesium alloys are the lightest of the casting metals, being about 60% as dense as aluminium alloy, and are used where weight saving is important, e.g. for portable saws, cameras, projectors and automobile components including specialised car wheels. The specification of these alloys is contained in BS EN 1753. 

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