Magnesium is the lightest of all metals used as the basis for constructional alloys, which is regarded as one of the most prospective metals in 21st century. Unfortunately, its poor corrosion resistance is the one of the main properties that has hindered its widespread use in many fields, particularly for outdoor applications. So it is valuable to strengthen its anti-corrosion performance through suitable surface treatment methods. Plasma electrolytic oxidation (PEO) is a new electrochemical surface treatme...