Tailoring the corrosion behavior and mechanism of AZ31 magnesium alloys by different Ca contents for marine application

Abstract The microstructure of AZ31 magnesium alloy was modified by Ca addition. AZ31-Ca alloys with refined microstructure exhibited significantly enhanced corrosion resistance in artificial seawater. AZ31-0.5Ca showed the lowest corrosion rate of 0.716 ± 0.186 mm y-1, which was about 7.4 times lower than that of AZ31 alloy (5.326 ± 0.652 mm y-1). The dominant role in the reduced corrosion rates of AZ31-Ca alloys gradually changed from the compact corrosion products film containing Al2O3 and CaCO3 to the corrosion barriers consisting of net-like (Mg, Al)2Ca phases as the Ca content increased from 0.1 wt.% to 1.5 wt.%.