等离子喷涂Al_(65)Cu_(23)Fe_(12)涂层的组织与性能研究

Microstructure and property of Al_(65)Cu_(23)Fe_(12) coating prepared by plasma spraying

采用等离子喷涂方法在AZ31镁合金表面制备一层Al65Cu23Fe12涂层以改善其表面性能。通过OM、XRD及EDS等分析方法,分析了涂层热处理前后的组织及性能。结果表明:等离子喷涂Al65Cu23Fe12涂层组织由Al65Cu20Fe15准晶相和Al(Cu,Fe)相两相组成;经过T4和T6处理后,相组成没有发生变化,T6处理使准晶相含量明显增加,由喷涂态的31.3%(原子分数)提高到40.4%(原子分数);Al65Cu23Fe12涂层的硬度与其准晶含量呈正比,T6态下的准晶含量最多,硬度最大,达到752.8HV0.1,比喷涂态提高了22.2%,远远大于AZ31基体的硬度;涂层的耐腐蚀性(自腐蚀电位=-1.22～-0.79V,自腐蚀电流密度=21.5～58.7A/m2)远高于基体的耐腐蚀性(自腐蚀电位=-1.6V,自腐蚀电流密度=135.8～242.7A/m2)。热处理使涂层和基体的耐蚀性能降低。

In order to improve the surface performance of AZ31 magnesium alloy, Al65Cu23Fe12 coating was prepared on the surface of the alloy by plasma spraying. The microstructures and properties of the coating were studied by means of OM, XRD, and EDS etc. The results showed that the coating consists of quasicrystalline Al65Cu20Fe15 phase and Al（Cu, Fe） phase. After T4 and T6 heat treatments, phase constituents of the coating remain unchanged, whereas the Al65Cu20Fe15 quasicrystal content in the coating increases from 31.3 at% to 40.4 at% after T6 heat treatment. The micro-hardness of the coating is in direct proportion to the Al65Cu20Fe15 quasicrystal content. The amount of Al65Cu20Fe15 in the coating after T6 treatment is the largest, so the microhardness of the coating is the highest, and equals 725.8HV0.1, which increases by 22.2% compared with that of the coating before heat treatment, and is much higher than that of the AZ31 alloy. Corrosion resistance of the coating （corrosion potential=-1.22--0.79V, corrosion current density=21.5-58.7A/m^2） is much higher than that of AZ31 alloy （corrosion potential =-1.6V, corrosion current density =135.8-242.7A/m^2）, whereas the corrosion resistance of both coating and AZ31 alloy decrease after heat treatment.