(1. 內(nèi)蒙古工業(yè)大學 材料科學與工程學院，呼和浩特 010050；
2. 內(nèi)蒙古自治區(qū)薄膜與涂層重點實驗室，呼和浩特 010050)
摘 要: 將質(zhì)量分數(shù)0.3%、0.9%稀土Y以及0.4%、1.0%(La, Ce)混合稀土分別添加到AZ91鎂合金中，采用掃描電子顯微鏡(SEM)、掃描開爾文探針力顯微鏡(SKPFM)以及電化學測試技術研究鎂合金的腐蝕行為。采用X射線衍射(XRD)、光電子能譜(XPS)測定腐蝕產(chǎn)物膜的組成和結(jié)構(gòu)，明確不同類型、不同含量的稀土對AZ91鎂合金腐蝕行為的影響規(guī)律。結(jié)果表明：兩種稀土均可以減緩AZ91鎂合金的腐蝕速率，提高合金的耐蝕性。不同類型稀土對AZ91鎂合金腐蝕行為影響的差異一方面取決于析出相與基體之間的電勢差，另一方面與稀土對鎂合金組織結(jié)構(gòu)及表面膜的影響機制有關。稀土La在腐蝕過程中參與生成的腐蝕產(chǎn)物增加了合金的表面膜的完整性，但表面膜的鈍化能力不及含Y鎂合金產(chǎn)生的鈍化作用，稀土Y降低合金中β-Mg17Al12相的質(zhì)量分數(shù)，減弱了其與鎂基體的微電偶腐蝕作用。稀土Y提高AZ91鎂合金耐蝕性的作用比(La, Ce)混合稀土更為明顯。添加0.9%Y鎂合金比添加0.3%Y鎂合金的腐蝕速率更低、耐蝕性更好。添加0.4%(La, Ce)混合稀土的鎂合金與添加1.0%(La, Ce)混合稀土鎂合金的耐蝕性相差不大。
關鍵字: 稀土；AZ91鎂合金；顯微組織；電化學；腐蝕
（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
