THE INFLUENCE OF ALLOYING AND IMPURITY ELEMENTS ON THE CORROSION OF MAGNESIUM ALLOYS

摘要

Magnesium (Mg) is a low density metal with excellent strength-to-weight ratio and casting properties - however its more widespread application in industry is currently limited by its poor corrosion resistance. Mg is an attractive alternative for application in the automotive industry as it can be used to replace both structural and drive-train components currently made of heavier metals. The immediate uptake on new Mg-based products by the automotive and other industries is restricted by the inherently high electrochemical reactivity of Mg and the inability to form a stable passive surface film. For this reason, Mg alloys display high rates of corrosion in neutral salt solutions. The effect of alloying elements has been considered in some detail in the context of mechanical properties however to date little has been detailed as to the effect of alloying elements on corrosion properties in a holistic manner. This work summarises a series of investigations which studied the effect of a range of common alloying and impurity elements on the corrosion behaviour of Mg and suggests methods of limiting aqueous corrosion of Mg through strategic alloy design.