邹安,邓运来,叶凌英,郭晓斌.7050铝合金局部腐蚀与电化学性能的关联性研究[J].表面技术,2022,51(10):226-234.
ZOU An,DENG Yun-lai,YE Ling-ying,GUO Xiao-bin.Correlation between Localized Corrosion and Electrochemical Performance of 7050 Aluminum Alloy[J].Surface Technology,2022,51(10):226-234
7050铝合金局部腐蚀与电化学性能的关联性研究
Correlation between Localized Corrosion and Electrochemical Performance of 7050 Aluminum Alloy
  
DOI:10.16490/j.cnki.issn.1001-3660.2022.10.023
中文关键词:  Al7Cu2Fe相  7050铝合金  原位腐蚀  电化学
英文关键词:Al7Cu2Fe phase  7050 aluminum alloy  in-situ corrosion  electrochemistry
基金项目:国家新材料生产应用示范平台建设项目重点项目(TC190H3ZV)
作者单位
邹安 中南大学 材料科学与工程学院,长沙 410083 
邓运来 中南大学 材料科学与工程学院,长沙 410083 
叶凌英 中南大学 材料科学与工程学院,长沙 410083 
郭晓斌 中南大学 材料科学与工程学院,长沙 410083 
AuthorInstitution
ZOU An School of Materials Science and Engineering, Central South University, Changsha 410083, China 
DENG Yun-lai School of Materials Science and Engineering, Central South University, Changsha 410083, China 
YE Ling-ying School of Materials Science and Engineering, Central South University, Changsha 410083, China 
GUO Xiao-bin School of Materials Science and Engineering, Central South University, Changsha 410083, China 
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中文摘要:
      目的 探明7050铝合金的点腐蚀机理。方法 利用ZEISSM10A扫描电子显微镜(SEM)和能谱仪(EDS)对在NaCl溶液中腐蚀不同时间的7050铝合金试样表面的Al7Cu2Fe相进行原位分析,并结合对应的电化学阻抗谱,研究Al7Cu2Fe相成分、尺寸的差异性对7050铝合金腐蚀性能的影响。结果 原位腐蚀结果表明,AlxCuyFe相的点蚀特征取决于相的尺寸和成分,AlxCuyFe相中Fe含量的变化率呈先增大后减小的趋势。其中Fe含量变化程度最大的是平均直径约1.7 μm的Al7Cu2Fe相,在经过1.5 h腐蚀后,其变化率达到了58.62%;其次是平均直径约2.4 μm的Al7Cu2Fe相,在经过1 h腐蚀后,其变化率为52.13%;而2.5 μm以上的Al7Cu2Fe相在点蚀过程中Fe含量的变化率大都在10%以下。电化学阻抗谱结果表明,T6态7050铝合金在150 g/L NaCl溶液中经过2 h腐蚀后阻抗最强,其Rp值为229.3 Ω,Rb值为2 801 Ω。结论 在150 g/L NaCl溶液中T6态7050铝合金表面点蚀主要发生在0.5~1.5 h以内,腐蚀2 h时合金已不受Al7Cu2Fe相引起的表面点蚀的影响。当浸泡时间达到2 h后,Al7Cu2Fe相尺寸、Fe含量都略有减小,相比未腐蚀状态Al7Cu2Fe相的总体面积减少了4.72%,Fe含量减少了7.59%。对Rb值影响较大的是平均直径为1.5~2.5 μm的Al7Cu2Fe相。
英文摘要:
      In order to explore the pitting corrosion mechanism of 7050 aluminum alloy and the influence of Al7Cu2Fe on the corrosion performance of 7050 aluminum alloy. In this paper, ZEISSM10A scanning electron microscope (SEM) and energy spectrometer (EDS) were used to analyze the Al7Cu2Fe phase on the surface of 7050 aluminum alloy samples corroded in NaCl solution for different time. Combined with the corresponding electrochemical impedance spectroscopy, the influence of the difference of Al7Cu2Fe phase composition and size on the corrosion performance of 7050 aluminum alloy was studied. The study found that the specific composition of the AlxCuyFe phase on the surface of the T6 7050 aluminum alloy is in the range of Al60.3Cu2.7Fe to Al7.4Cu2Fe, so the second phase of the Al7Cu2Fe type is studied in this paper. And with the increase of the size of the Al7Cu2Fe phase, its Fe content tends to increase overall. Among them, the Al7Cu2Fe phase with the size in the range of 1.5-3 μm has the largest number and the largest area, accounting for 79.1% of the total Al7Cu2Fe phase area. The in-situ corrosion results show that the pitting characteristics of the AlxCuyFe phase depend on the size and composition of the phase, and the change rate of Fe content in the AlxCuyFe phase first increases and then decreases. Among them, the largest change in Fe content is the Al7Cu2Fe phase with an average diameter of about 1.7 μm. After 1.5 h of corrosion, the change rate reaches 58.62%. Secondly, the Al7Cu2Fe phase with an average diameter of about 2.4 μm has a change rate of 52.13% after 1 h of corrosion, while the Fe content change rate of the Al7Cu2Fe phase with an average diameter of about 2.4 μm during the pitting corrosion process is mostly below 10%. The results of electrochemical impedance spectroscopy showed that the Rs value of the samples after different corrosion treatments changed greatly. The Rs value of the sample after corrosion for 0.5 h was the highest, reaching 29.84 Ω, and the Rs value of the sample after corrosion for 1.5 h was the lowest, which was 2.20 Ω. The resistance of 7050 aluminum alloy in T6 state after being immersed and corroded in a NaCl solution with a concentration of 150 g/L decreases first and then increases. After 2 h of corrosion, the resistance is the strongest, with Rp value of 229.3 Ω and Rb value it is 2 801 Ω. Therefore, we can find that the surface pitting corrosion of 7050 aluminum alloy in T6 state in 150 g/L NaCl solution mainly occurs within 0.5 h to 1.5 h, and the alloy is not affected by surface pitting corrosion caused by Al7Cu2Fe phase after 2 h corrosion. When the immersion time reaches 2 h, the size and Fe content of the Al7Cu2Fe phase are slightly reduced. Compared with the uncorroded state, the overall area of the Al7Cu2Fe phase is reduced by 4.72%, and the Fe content is reduced by 7.59%. The Al7Cu2Fe phase with an average diameter in the range of 1.5-2.5 μm has a greater influence on the Rb value. In summary, the main influence on the pitting corrosion performance of 7050 alloy is the AlxCuyFe phase with a size range of 1.5-2.5 μm. The Fe content and size change during the corrosion process are more significant than those in the size range of 2.5-9.5 μm.
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