Impact of cooling rate on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy  

冷却速率对含锂7xxx铝合金抗剥落腐蚀性能的影响

作　　者：JIANG Ke-da LIAO Ze-xin CHEN Ming-yang LIU Sheng-dan TANG Jian-guo 姜科达;廖泽鑫;陈明扬;刘胜胆;唐建国(School of Materials Science and Engineering,Central South University,Changsha 410083,China;National Key Laboratory of Science and Technology on High-strength Structural Materials,Central South University,Changsha 410083,China;Key Laboratory of Non-ferrous Metals Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China)

机构地区：[1]School of Materials Science and Engineering,Central South University,Changsha 410083,China [2]National Key Laboratory of Science and Technology on High-strength Structural Materials,Central South University,Changsha 410083,China [3]Key Laboratory of Non-ferrous Metals Materials Science and Engineering,Ministry of Education,Central South University,Changsha 410083,China

出　　处：《Journal of Central South University》2024年第7期2225-2236,共12页中南大学学报（英文版）

基　　金：Project(202302AB080024)supported by the Major Science and Technology Projects of the Science and Technology Department of Yunnan Province,China;Project(U21A20130)supported by the National Natural Science Foundation of China。

摘　　要：The impact of cooling rate after solution heat treatment on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy was investigated by accelerated immersion and electrochemical impedance spectroscopy test,optical microscope,electron backscatter diffraction and scanning transmission electron microscope.With the decrease of cooling rate from 1700℃/s to 4℃/s,exfoliation corrosion resistance of the aged specimens decreases with rating changing from EA to EC and the maximum corrosion depth increasing from about 169.4μm to 632.1μm.Exfoliation corrosion tends to develop along grain boundaries in the specimens with cooling rates higher than about 31℃/s and along both grain boundaries and sub-grain boundaries in the specimens with lower cooling rates.The reason has been discussed based on the changes of the microstructure and microchemistry at grain boundaries and sub-grain boundaries due to slow cooling.采用加速浸泡、电化学阻抗谱测试、光学显微镜、电子背散射衍射和扫描透射电镜等方法,研究固溶热处理后冷却速度对含锂7xxx铝合金抗剥落腐蚀性能的影响。随着冷却速率从1700℃/s降低到4℃/s,时效试样的抗剥落腐蚀性能下降,等级从EA变为EC,最大腐蚀深度从169.4μm增加到632.1μm。在冷却速率大于31℃/s的试样中,剥落腐蚀倾向于沿晶界发展;在冷却速率较低的试样中,剥落腐蚀倾向于沿晶界和亚晶界发展。从缓慢冷却引起的晶界和亚晶界组织和微化学变化的角度分析了差异原因。

关 键 词：7xxx aluminum alloy cooling rate exfoliation corrosion microstructure 

分 类 号：TG172[金属学及工艺—金属表面处理]