人工时效对7075铝合金微观腐蚀行为的影响

Effect of artificial aging on micro⁃corrosion behavior of 7075 aluminum alloy

通过腐蚀电化学测量、扫描电镜、透射电镜和EDS元素分析,研究了时效时间对7075铝合金腐蚀行为的影响。结果表明,在120℃下时效6 h的合金试样较时效2、12、24 h的合金试样自腐蚀电位更正,腐蚀驱动力更小,合金更不易发生腐蚀。随着时效时间的增加,合金整体腐蚀形貌由晶间腐蚀转变为点蚀。利用透射电镜观察合金基体早期腐蚀形貌发现,时效6 h的合金表面呈现均匀分布的腐蚀浅坑,而时效24 h试样则呈现小而深的点蚀,基体溶质元素分布均匀程度对合金腐蚀行为有较大影响。

Effect of aging time on corrosion behavior of the 7075 aluminum alloy was investigated by means of corrosion electrochemical measurements,scanning electron microscope,transmission electron microscope and EDS elemental analysis.The results show that the specimen aged for 6 h at 120℃has a higher self⁃corrosion potential and a lower corrosion driving force than the specimens aged for 2,12 and 24 h,and the alloy aged for 6 h is less prone to corrosion.As the aging time increases,the overall corrosion profile of the alloy changes from intergranular corrosion to pit corrosion.Through the early corrosion morphologies of the substrate observed by using transmission electron microscope,the alloy aged for 6 h shows uniformly distributed shallow corrosion hollows on the surface,while the alloy aged for 24 h shows deep corrosion pits.The uniform distribution extent of solute elements in the substrate has a significant impact on the pitting behavior of the alloy.