(沈阳工业大学材料科学与工程学院，沈阳 110870)
摘 要: 为探究和改善7xxx系铝合金耐腐蚀性能，采用电化学分析和透射电镜观察等手段，针对7075铝合金回归再时效(RRA)处理过程中的不同回归程度进行电化学腐蚀行为研究。结果表明：较为充分的回归处理有利于基体析出相回溶，经再时效处理后基体析出相细小弥散，有利于钝化膜的修补；晶界析出相粗大且断开分布，阻断腐蚀通道，延缓腐蚀的进行；较为明显的晶间无析出带，更大程度地减缓了基体与晶界析出相之间的电位差，缓解合金的腐蚀敏感性。RRA处理后的合金电化学腐蚀抗性均优于峰值时效处理的，经过120 ℃预时效20 h、190 ℃回归15 min、120 ℃再时效20 h处理的样品在电化学腐蚀过程中自腐蚀电位、自腐蚀电流密度和腐蚀速率分别为-1.12 V、3.4 μA/cm2和为0.11 mm/a，电化学腐蚀抗性得到显著改善。
关键字: 7075铝合金；电化学；析出相；极化曲线；阻抗
（School of Materials Science and Engineering, Shenyang University of
Technology, Shenyang 110870, China）
Abstract:In order to explore and improve the corrosion resistance of 7xxx series aluminum alloys, the electrochemical corrosion behavior of 7075 aluminum alloy treated via retrogression and re-aging (RRA) with different retrogression was studied by electrochemical analysis and transmission electron microscope. The results show that a more adequate retrogression treatment is beneficial to re-dissolution of matrix precipitates. After re-aging treatment, the matrix precipitates are fine and dispersed, which are conducive to repair the passivation film. In addition, the coarse and disconnected grain boundary precipitates are blocking the corrosion channel and delaying the progress of corrosion. A more obvious precipitate-free zone effectively reduces the potential difference between the matrix and the grain boundary precipitates, and the corrosion sensitivity of the alloy is alleviated. The electrochemical corrosion resistance of RRA-treated alloy is better than that of peak-aged. The self-corrosion potential, self-corrosion current density and corrosion rate of the sample, which is pre-aged at 120 ℃ for 20 h, retrogression at 190 ℃ for 15 min and re-aged at 120 ℃ for 20 h, are -1.12 V, 3.4 μA/cm2 and 0.11 mm/a, respectively. The electrochemical corrosion resistance is remarkably improved.
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