Effect of Zn Addition on Corrosion Behavior of Mg-8%Al Casting Alloy

Abstract

Effects of Zn addition on the microstructure and corrosion behavior of Mg-8%Al-(0-1)%Zn casting alloys were investigated. With increasing Zn content, the amount of β(Mg 17 Al 12 ) phase increased, while α-(Mg) dendritic cell size became reduced. The corrosion rate decreased continuously with the increase in the Zn content. The evaluation of the microstructural evolution indicates that the improved barrier effect of β particles formed more continuously along the dendritic cell boundaries and the incorporation of more ZnO into the surface corrosion product, by which the absorption of Cl − ions is impeded, are responsible for the better corrosion resistance in relation to the Zn addition.