固溶处理对Mg-6Al-5Pb-1.5In阳极腐蚀电化学性能的影响

金和喜^{1, 2}，王日初¹，彭超群¹，石 凯¹，陈雅谨¹, 许泽辉²

(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 永杰新材料股份有限公司，杭州 311222)

摘 要：在3.5% NaCl(质量分数)溶液中测定铸态和经固溶处理的Mg-6Al-5Pb-1.5In镁合金阳极的腐蚀电化学性能，采用金相(OM)、扫描电镜(SEM)和能谱分析(EDS)分别研究其显微组织、截面腐蚀形貌及相组成。结果表明：固溶后β-Mg₁₇Al₁₂相基本溶入α-Mg基体，降低微电偶腐蚀中阴极与阳极的面积比，增大阳极自腐蚀速率；Mg₂Pb相的自腐蚀电位比镁基体正，固溶后Pb以Mg₂Pb相析出，阳极表面腐蚀后晶粒中央的Mg₂Pb相并没有被腐蚀。Al含量是决定镁阳极中各相腐蚀速率的关键，相表面形成的保护膜中Al含量越高，对基体保护性能越好。

关键词：镁阳极；固溶处理；腐蚀电化学性能

Effects of solution treatment on corrosion electrochemical properties of Mg-6Al-5Pb-1.5In anodes

JIN He-xi^{1, 2}, WANG Ri-chu¹, PENG Chao-qun¹, SHI Kai¹, CHEN Ya-jin1, XU Ze-hui²

(1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Yongjie New Material Co., Ltd., Hangzhou 311222, China)

Abstract:The corrosion electrochemical properties of as-cast and solid-solution-treated Mg-6Al-5Pb-1.5In alloy anodes were examined in 3.5% NaCl (mass fraction) solution. The microstructures, cross-sectional corrosion morphologies and composition of phases in the anodes were studied by optical microscopy (OM), scanning electronic microscopy (SEM)and energy dispersive spectrometry (EDS), respectively. The experimental results show that, the β-Mg₁₇Al₁₂ phase dissolves into the α-Mg matrix, the cathode-to-anode area ratio of the anodes decreases, and the self-corrosion rates increase after solution treatment. Pb segregates in the form of Mg₂Pb and the electro-negativity of Mg₂Pb is more positive than that of the α-Mg matrix, which results in the un-corroded Mg₂Pb existing in the center of the corroded area at the surfaces of anodes. The aluminum content is a dominant factor of corrosion rate in magnesium anodes, and the higher the aluminum content of the protective film is, the better the protective properties to matrix is.

Key words:magnesium anodes; solution treatment; corrosion; electrochemical properties