(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 中南大学 轻合金研究院，长沙 410083；
3. 中南大学 有色金属材料科学与工程教育部重点实验室，长沙 410083)
摘 要: 借助扫描电子显微镜(SEM)和X射线衍射(XRD)对AZ31-xCu(x=0，0.5，1.5，3，质量分数，%)合金的铸态组织、相结构及表面腐蚀形貌进行测试和分析。采用浸泡试验和电化学试验对研究合金在3.5%氯化钠溶液中的腐蚀行为进行系统地对比研究。结果表明：随铜含量的增加，研究合金中的主要第二相AlCuMg相递增；腐蚀过程的主要腐蚀机制是微电偶腐蚀，AlCuMg相作为微电偶腐蚀阴极与镁基体阳极构成微电偶腐蚀对，随AlCuMg相体积分数增加，形成的微电偶腐蚀对增多，相应的腐蚀速率增大。当铜含量为3%时，研究合金的腐蚀速率最大，研究合金的析氢速率和腐蚀电流密度分别为：75？mL/(cm2？d)和698？μA/cm2。
关键字: AZ31-xCu合金；AlCuMg相；腐蚀速率；微电偶腐蚀阴极；镁基体阳极
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Light Alloy Research Institute, Central South University, Changsha 410083, China;
3. Key Laboratory of Nonferrous Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China）
Abstract:The as-cast microstructure, phase composition and surface corrosion morphologies of AZ31-xCu(x=0, 0.5, 1.5, 3, mass fraction, %) alloys were observed by scanning electron microscope (SEM) equipped with energy dispersive spectroscope (EDS) and X-ray diffraction (XRD). The corrosion behavior of the alloys in 3.5% NaCl solution was investigated by immersion test and electrochemical test. The results indicate that the content of AlCuMg phase, main secondary phase in the Cu-containing alloys, is positively dependent on copper concentration. Acceleration of corrosion rate is found in Cu-containing alloys due to micro-galvanic corrosion. AlCuMg phase acts as micro-galvanic cathode against anodic magnesium matrixes. The corrosion rate of the alloy with Cu content of 3% is the fastest. The AZ31-3Cu alloy exhibits the maximum hydrogen evolution rate of 275？mL/(cm2？d-1) and corrosion current density of 698？μA/cm2.
Key words: AZ31-xCu alloy; AlCuMg phase; corrosion rate; micro-galvanic cathode; anodic magnesium matrixe
