(沈陽(yáng)工業(yè)大學(xué)材料科學(xué)與工程學(xué)院，沈陽(yáng) 110870)
摘 要: 為探究和改善7xxx系鋁合金耐腐蝕性能，采用電化學(xué)分析和透射電鏡觀察等手段，針對(duì)7075鋁合金回歸再時(shí)效(RRA)處理過(guò)程中的不同回歸程度進(jìn)行電化學(xué)腐蝕行為研究。結(jié)果表明：較為充分的回歸處理有利于基體析出相回溶，經(jīng)再時(shí)效處理后基體析出相細(xì)小彌散，有利于鈍化膜的修補(bǔ)；晶界析出相粗大且斷開(kāi)分布，阻斷腐蝕通道，延緩腐蝕的進(jìn)行；較為明顯的晶間無(wú)析出帶，更大程度地減緩了基體與晶界析出相之間的電位差，緩解合金的腐蝕敏感性。RRA處理后的合金電化學(xué)腐蝕抗性均優(yōu)于峰值時(shí)效處理的，經(jīng)過(guò)120 ℃預(yù)時(shí)效20 h、190 ℃回歸15 min、120 ℃再時(shí)效20 h處理的樣品在電化學(xué)腐蝕過(guò)程中自腐蝕電位、自腐蝕電流密度和腐蝕速率分別為-1.12 V、3.4 μA/cm2和為0.11 mm/a，電化學(xué)腐蝕抗性得到顯著改善。
關(guān)鍵字: 7075鋁合金；電化學(xué)；析出相；極化曲線；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.
Key words:
