(1. 中南大学 材料科学与工程学院，长沙 410083；
2. 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；
3. 中国兵器科学研究院 宁波分院，宁波 315103)
摘 要: 利用金相显微镜(OM)、扫描电镜(SEM)、能谱分析(EDS)、X射线衍射分析、集气法及动电位极化曲线研究了微量Er对铸态AZ91镁合金显微组织和腐蚀性能的影响。结果表明：微量Er可细化AZ91镁合金的铸态组织，当AZ91镁合金中加入Er的含量不高于0.7%(质量分数)时，随着Er含量的增加，镁合金中的γ-Mg17Al12相由粗大、连续块状分布逐渐转变为细小、岛状均匀分布，并且有Al3Er相生成；同时，微量Er也可显著提高铸态AZ91的耐腐蚀性能，当Er含量为0.7%时，合金耐蚀性能大幅度提高，在3.5%(质量分数)NaCl水溶液中浸泡的腐蚀速率为0.546 06 mg/(cm2·d)，仅为常规AZ91镁合金的1/15；微量Er使得AZ91镁合金在3.5% NaCl溶液中的自腐蚀电位升高，自腐蚀电流降低，从而提高AZ91镁合金的耐腐蚀性能。
关键字: AZ91镁合金；Er；显微组织；腐蚀性能
AZ91 magnesium alloy
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education,
Central South University, Changsha 410083, China;
3. Ningbo Branch, Ordnance Science Institute of China, Ningbo 315103, China）
Abstract: The microstructure and corrosion behavior of AZ91 magnesium alloys with trace addition of Er were investigated by optical microscopy (OM), scanning electronic microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffractometry (XRD), collecting gas, immersion test and potention dynamic polarization. The results show that with Er addition in the range of 0%−0.7% (mass fraction), the γ-Mg17Al12 phase is refined with increasing Er addition and disperses well in the matrix, and Al3Er phase forms. The corrosion resistance of alloy is significantly improved. The alloy with 0.7% Er has the best corrosion resistance, and the corrosion rate is 0.546 06 mg/(cm2·d), only 1/15 of that of common AZ91 alloy. Trace addition of Er enhances the electrode voltage and lowers the corrosion current of AZ91 alloy in 3.5% NaCl solution, thus improves the corrosion characters of magnesium alloy.
Key words: AZ91 magnesium alloy; Er; microstructure; corrosion resistance
