中文摘要：

采用AlCl3-NaCl熔盐自发置换扩散工艺在AZ91D镁合金表面制备镁铝金属间化合物涂层,并利用开路电位、电化学阻抗方法对镁合金及熔盐置换扩散改性处理试样在3.5%（质量分数）NaCl溶液中的腐蚀行为进行比较研究。结果表明：熔盐自发置换扩散铝涂层在温度为400℃,保温8h的工艺条件下呈现出了明显的分层结构特征。根据组织结构不同,可将其分为：颗粒状形貌的外层和具有网状结构的内层;经表面熔盐自发置换扩散处理后的镁合金试样,腐蚀电位比未改性的AZ91D镁合金大幅提高,膜层阻抗约为未改性的AZ91D镁合金的10倍。

英文摘要：

A dense and adhesive multilayer coating on AZ91D magnesium was successfully obtained by AlCl3-NaCl molten salt bath treatment.The corrosion resistance of AZ91D alloy without and with coating by a multilayer Mg-Al intermetallic compound was evaluated by open circuit potential and electrochemical impedance spectroscopy measurements in 3.5%（mass fraction）NaCl solutions.A multilayer structure was observed in the alloyed coating at 400℃ with 8h treatment time.The inner layer of alloyed coating presents network feature,while the outer layer of alloyed coating is composed of cubical shape particles.The coated sample shows higher open circuit potential than the uncoated one.The coating polarization resistance value of the coated sample is ten times greater.