A novel AZ91 Ce containing magnesium alloy characterized by excellent corrosion resistance is fabricated by adding rare earth Ce (cerium) in the form of a Mg-Ce master alloy. The metallographic investigation shows that Ce added to AZ91 can obviously decrease the size of b-Mg 17 Al 12 and forms Al 11 Ce 3 intermetallic compounds in the shape of fine needles. The corrosion tests and electrochemical measurements indicate that the corrosion resistance of AZ91 Ce containing magnesium alloy is obviously higher than that of AZ91. Furthermore, increasing the content of Ce in the magnesium alloy can further enhance the corrosion resistance. X-ray photoelectron spectroscopy (XPS) reveals that Ce can be incorporated into corrosion products in the form of CeO 2 in the course of corrosion. Based on the preliminary analysis, the addition of Ce can improve the corrosion resistance of AZ91 by decreasing the size of bMg 17 Al 12 and enhancing the protective effectiveness of corrosion products.
Micro-arc oxidation (MAO) is very effective to enhance the corrosion performance of Mg alloys. However, the micro-pores in MAO coatings provide a channel for the corrosion medium to reach the alloy matrix. In this work, electron beam strengthening (EBS) is performed to improve the microstructure of the Mg alloy and the MAO coating is prepared subsequently to improve the corrosion performance. The crystalline size of the Mg alloy decreases, the roughness improves, and the corrosion resistance increases. Furthermore, refinement of the grain size by EBS improves the discharge in MAO. The noticeable effect of EBS on the microstructure of the coating lies in the improvement of density, such as porosity reduction by 47.8%. The compactness of the coatings also increases significantly, subsequently improving the corrosion resistance. The corrosion mechanism is proposed.
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