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通过真空热扩渗技术在AZ31B镁合金表面制备一层合金化涂层。采用OM、SEM、EDS及XRD等方法分析合金化涂层的显微组织、成分和相组成,并利用显微硬度计和PS-168a型电化学腐蚀测试系统分别对合金化涂层的显微硬度和耐腐蚀性能进行测试分析。研究结果表明:恒温条件下,随着保温时间的延长,在AZ31B镁合金表面可以形成合金化涂层。随着保温时间的延长,涂层与基体之间结合界面形貌由平直结合转变成“锯齿”状咬合;且合金化涂层与基体之间存在明显的过渡层,过渡层逐渐变宽。EDS及XRD分析结果表明,合金化涂层为Mg-Al共晶组织α-Mg和β-Al_(12)Mg_(17),合金化涂层的平均显微硬度比基体的平均显微硬度提高了113%;自腐蚀电位也由基体的-1.389 V提高到-1.268 V。
A layer of alloying coating was prepared on the surface of AZ31B magnesium alloy by vacuum thermal expansion technique. The microstructure, composition and phase composition of the alloying coating were analyzed by OM, SEM, EDS and XRD. The micro-hardness and PS-168a electrochemical corrosion testing system were used to analyze the microstructure, Hardness and corrosion resistance test analysis. The results show that the alloy coating can be formed on the surface of AZ31B magnesium alloy under the condition of constant temperature with the extension of holding time. As the holding time prolongs, the bonding interface between the coating and the substrate changes from flat bonding to “serrated” bite; and there is a clear transition layer between the alloying coating and the substrate, and the transition layer gradually changes width. The results of EDS and XRD show that the average microhardness of the alloying coating is higher than that of the matrix by Mg-Al eutectic α-Mg and β-Al 12 Mg 17. 113%. The corrosion potential also increased from -1.389 V to -1.268 V in the matrix.