(1. 浙江大学 化学系， 杭州 310027；
2. 中国科学院 金属研究所
金属腐蚀与防护国家重点实验室， 沈阳110015)
摘 要: 研究了LC4铝合金双级过时效处理板材在EXCO剥蚀溶液中的剥蚀行为及其相应的电化学阻抗谱。 结果表明， 腐蚀由晶界孔蚀发展为沿平行于表面的晶界腐蚀， 并在晶界堆积大体积的楔形腐蚀产物，挤压表层晶粒而导致剥蚀。 由于双级过时效处理使强化相η 均匀析出， 降低了合金的晶间腐蚀程度， 导致合金剥蚀程度很轻， 主要表现为局部小面积的金属表层鼓泡剥蚀。 剥蚀后， 电化学阻抗谱由两个容抗弧组成，其中高频容抗弧源于合金原表面， 而中低频容抗弧源于剥蚀后露出并与腐蚀介质接触的新界面。 有可能根据这两个容抗成分的分析来定量判断合金的剥蚀程度。
关键字: LC4铝合金； 剥蚀； 电化学阻抗
（1. Department of Chemistry, Zhejiang University, Hangzhou 310027, China;
2. State Key Laboratory for Metals Corrosion and Protection, Institute of Metals Research,The Chinese Academy of Sciences,
Shenyang 110015, China）
Abstract:The exfoliation corrosion and electrochemical impedance spectroscopy of over-aged LC4 alloy in EXCO solution were studied. During the corrosion process, pitting corrosion occurs at grain boundary first, then corrosion propagates along grain boundary parallel to the alloy surface, the corrosion product accumulates in the grain boundary and lifts the surface.η(MgZn2) phase is well-distributed due to over-aging heat treatment and intergranular corrosion is detered. As a result, the exfoliation degree is superficial and the exfoliation morphology displays as localized blisters. After exfoliation, the impedance spectroscopy is composed of two capacitive arcs, one results from original flat alloy surface, the other from the new interface contacted with the EXCO solution. It is supposed that exfoliation degree can be judged through the analysis of these two capacitive components.
Key words: LC4 aluminum alloy; exfoliation corrosion; electrochemical impedance spectroscopy
