Corrosion behaviour of Mg-alloy AZ91E with atypical alloying additions

Magnesium alloys are the lightest of all the structural metals with good strength/weight ratio and castability, however their application continues to be severely limited by relatively poor resistance to corrosion. Unlike most passivating metallic materials which develop their own protective surface oxide, magnesium suffers continued dissolution in neutral chloride solutions. AZ91E is a widely used magnesium-based alloy, which exhibits a balance between mechanical properties and moderate corrosion resistance; this work explores the affect of atypical alloying additions on the corrosion behaviour of this alloy. Results are presented in the form of a survey, along with an ensuing discussion of electrochemical test results and microscopy. It is noted that several elements are beneficial in improving corrosion resistance of AZ91E, while others accelerate corrosion rather dramatically.