Improved corrosion resistance of AZ91D magnesium alloy by a zinc-yttrium coating

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• 作者：Hongxia Wang ; Bin Yu ; Weiwei Wang ; Guangxiao Ren ; Wei Liang ; Jinshan Zhang
• 关键词：AZ91D magnesium alloy ; Zinc&ndash ; yttrium coating ; Microstructure ; Corrosion resistance
• 刊名：Journal of Alloys and Compounds
• 出版年：2014
• 出版时间：5 January, 2014
• 年：2014
• 卷：582
• 期：Complete
• 页码：457-460
• 全文大小：921 K

文摘

A zinc-yttrium coating on AZ91D magnesium alloy was conducted by diffusion treatment in order to improve its corrosion resistance and wear resistance. The microstructures and phase constituents of the zinc-yttrium coating were investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrum (EDS). The results reveal that a zinc-yttrium coating has been formed on the surface of magnesium specimens by the solidification of the liquid layer formed between the AZ91D magnesium alloy and the Zn, Y mixed powders. The microstructure of the zinc-yttrium coating is typical eutectic structure, which contains a large amount of intermetallic compound, such as Mg₅Al₂Zn₂. In addition, the microhardness values of the intermetallic compounds are much higher than those of the substrate and this would greatly contribute to the enhancement of wear resistance. The results of electrochemical corrosion tests in 3.5 wt. % NaCl solution show that the corrosion resistance of the coated specimens has been increased significantly.