Microstructure and Corrosion Behavior of Magnesium Alloy with the Addition of Ce

The microstructure and corrosion properties of AZ91D magnesium alloys with the addition of Ce were observed and analyzed.The results indicated that the casting microstructure was refined obviously and reticular β-phase that exhibited graininess dispersion was distributed at grain boundaries,and a large amount of spicule Al4Ce phase appeared when the addition of Ce was 0.69%.But when the addition of Ce was 0.93%,the casting microstructure of the alloy was more coarse and spicule compound grow up to be rhabditiform.The corrosion rate of the alloy with the 0.26% Ce and 0.93% Ce increased rapidly in the beginning and then reduced obviously;but the corrosion rate of the alloy with 0.69% Ce kept constant.The corrosion rate of AZ91D magnesium alloy increased with the increase of NaCl concentration;The corrosion rate of the alloy with 0.26% Ce increased slowly;The corrosion rate of the alloy with 0.69% Ce decreased with the increase of NaCl concentration;The corrosion rate of the alloy with 0.93% Ce increased a little in low concentration,but decreased quickly in high NaCl concentration.The corrosion feature showed non-uniform corrosion.The corrosion product mainly consisted of Mg(OH)2.There was Al4Ce compound observed in the corrosion products of AZ91D magnesium alloys with Ce.The improvement of corrosion resistance of the alloy with Ce resulted from the refinment of microstructure and reduction of segregation of Al element.