(1. 内蒙古工业大学 材料科学与工程学院，呼和浩特 010050；
2. 内蒙古自治区薄膜与涂层重点实验室，呼和浩特 010050)
摘 要: 将质量分数0.3%、0.9%稀土Y以及0.4%、1.0%(La, Ce)混合稀土分别添加到AZ91镁合金中，采用扫描电子显微镜(SEM)、扫描开尔文探针力显微镜(SKPFM)以及电化学测试技术研究镁合金的腐蚀行为。采用X射线衍射(XRD)、光电子能谱(XPS)测定腐蚀产物膜的组成和结构，明确不同类型、不同含量的稀土对AZ91镁合金腐蚀行为的影响规律。结果表明：两种稀土均可以减缓AZ91镁合金的腐蚀速率，提高合金的耐蚀性。不同类型稀土对AZ91镁合金腐蚀行为影响的差异一方面取决于析出相与基体之间的电势差，另一方面与稀土对镁合金组织结构及表面膜的影响机制有关。稀土La在腐蚀过程中参与生成的腐蚀产物增加了合金的表面膜的完整性，但表面膜的钝化能力不及含Y镁合金产生的钝化作用，稀土Y降低合金中β-Mg17Al12相的质量分数，减弱了其与镁基体的微电偶腐蚀作用。稀土Y提高AZ91镁合金耐蚀性的作用比(La, Ce)混合稀土更为明显。添加0.9%Y镁合金比添加0.3%Y镁合金的腐蚀速率更低、耐蚀性更好。添加0.4%(La, Ce)混合稀土的镁合金与添加1.0%(La, Ce)混合稀土镁合金的耐蚀性相差不大。
关键字: 稀土；AZ91镁合金；显微组织；电化学；腐蚀
（1. School of Materials Science and Engineering, Inner Mongolia University of Technology, Hohhot 010050, China;
2. Key Laboratory for Thin Film and Coatings of Inner Mongolia Autonomous Region, Hohhot 010050, China）
Abstract:0.3%, 0.9% (mass fraction) rare earth Y and 0.4%, 1.0% (La, Ce) mixed rare earth were added to the AZ91 Mg alloy, respectively. Scanning electron microscopy (SEM), scanning Kelvin probe force microscopy (SKPFM) and electrochemical testing techniques were used to study the corrosion behavior of Mg alloy. X-ray diffraction (XRD) and photoelectron spectroscope (XPS) were used to determine the composition and structure of the corrosion product film. It was clarified that the influence of different types and contents of rare earth on the corrosion behavior of AZ91 Mg alloy. The results show that both rare earth elements can reduce the corrosion rate and improve the corrosion resistance of AZ91 Mg alloy. The effect of different types of rare earth on corrosion behavior of AZ91 Mg alloy depends not only on the potential difference between the precipitated phase and the matrix, but also on the influence mechanism of rare earth on the microstructure and surface film of Mg alloy. Rare earth La participates in the formation of corrosion products during the corrosion process, which increases the integrity of the surface film, but the passivation ability of the surface film is not as good as the passivation effect produced by the Y-containing Mg alloy. Rare earth Y reduces the mass fraction of β-Mg17Al12 phase in the alloy and weakens its micro-galvanic corrosion effect. The role of rare earth Y in improving the corrosion resistance is more obvious than that of (La, Ce) mixed rare earth. The corrosion rate of AZ91 Mg alloy with 0.9%Y addition is lower than that of Mg alloy containing 0.3%Y. The corrosion resistance of Mg alloy with 0.4% (La, Ce) mixed rare earth is similar to that of Mg alloy with 1.0% (La, Ce).
Key words: rare earth; AZ91 Mg alloy; microstructure; electrochemistry; corrosion
