Microstructure And Corrosion Resistance Of AZ91 Magnesium Alloy Modified By Rare Earth

Magnesium alloys, with low density, high special strength and rigidity, good electromagnetic shielding characteristics, high damping characteristics, good machinability and easy to be recycled, have become promising materials for various machines. However, the poor corrosion resistance of magnesium alloys has been becoming the"bottle-neck"in their application. Both rare earth (RE) alloying and micro-arc oxidation (MAO) are effective methods to improve the corrosion resistance of magnesium alloys. Nevertheless, at present, the research in the two areas is not systemic and cannot provide the academic support and practical instruction. As for RE alloying, the present research mainly concentrates on the preparation of magnesium alloys with good corrosion resistance and their performance evaluation by adding misch metal (MM), but the researches on effect mechanism of the single RE element are not extensive. As for MAO, the present researches mainly focus on the dependence of electrolyte compositions, electric parameters on the microstructures, compositions and performances of MAO coatings, but it is not clear about the interrelation between the microstructures of magnesium alloys modified by RE and the microstructures and performance of MAO coatings, on which the further researching is necessary. Based on the above insufficiencies in corrosion researching of magnesium alloys, some valuable researches have been done and some innovative results have been obtained in this dissertation.Firstly, AZ91RE magnesium alloys have been successfully prepared by adding...