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稀土元素及其含量对铝合金耐腐蚀性能的影响及其机制是铝合金开发利用的重要研究课题,采用高频熔炼方法制备Al1-xCex(x=0,0.2%,2.0%(原子分数))合金,通过X射线衍射、金相分析、电化学测试、扫描电镜和能谱等分别对制备的Al1-xCex合金的结构、动电位线性扫描极化曲线、浸泡与电化学腐蚀前后表面形貌的变化进行了研究;对Al1-xCex在3.5%NaCl溶液中耐腐蚀性能与铈含量的关系进行了系统的分析。结果表明:由于Cl-离子的存在,铝在3.5%NaCl溶液中发生点蚀破坏;稀土Ce的加入能够细化晶粒,改善合金微观结构,减弱Cl-离子对点蚀的影响;Ce元素在腐蚀表面层富集,有利于形成连续钝化膜,提高合金在NaCl溶液中的耐蚀能力;微量稀土Ce(0.2%)的加入使合金的自腐蚀电位升高,腐蚀电流密度降低,耐腐蚀性能改善明显;但随着Ce含量的增加,即含量高于铈在铝中的溶解度后,铝与铈将形成金属间化合物,基底与金属间化合物相界面的存在使合金的耐腐蚀性能有所降低,Ce含量为0.2%合金的耐腐蚀性能比Ce含量为2.0%的合金要好。所有合金腐蚀后的主要产物为Al2O3。
The effects of rare earth elements and their contents on the corrosion resistance of aluminum alloys and their mechanisms are important research topics for the development and utilization of aluminum alloys. Al1-xCex (x = 0, 0.2%, 2.0%) was prepared by high- Alloys were characterized by X-ray diffraction, metallographic analysis, electrochemical tests, scanning electron microscopy and energy dispersive spectroscopy. The structures of the prepared Al1-xCex alloys, the polarization curves of potentiodynamic potentials and the surface morphologies before and after immersion and electrochemical etching The relationship between the corrosion resistance of Al1-xCex and the content of cerium in 3.5% NaCl solution was systematically analyzed. The results show that due to the presence of Cl- ions, pitting corrosion occurs in 3.5% NaCl solution. The addition of rare earth Ce can refine the grains, improve the microstructure of the alloy and weaken the effect of Cl- ions on the pitting corrosion. The enrichment of corrosion surface layer is conducive to the formation of a continuous passivation film to improve the corrosion resistance of the alloy in NaCl solution. The addition of trace rare earth Ce (0.2%) increases the self-corrosion potential of the alloy, decreases the corrosion current density, However, with the increase of Ce content, ie, the content is higher than the solubility of cerium in aluminum, aluminum and cerium will form intermetallic compounds. The existence of interface between substrate and intermetallic compound will make the corrosion resistance of alloy Decreasing, the Ce content of 0.2% alloy corrosion resistance than the Ce content of 2.0% better. The main product of all the alloys after corrosion is Al2O3.