中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 24 No. 12 December 2014 |
（1. State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, Tianjin 300072, China;
2. Tianjin Key Laboratory of Composite and Functional Materials,
School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China）
Abstract:The pitting corrosion behaviors of 7A60 aluminum alloy in the retrogression and re-aging (RRA) temper were investigated by electrochemical impedance spectroscopy (EIS) and electrochemical noise (EN) techniques, and the microstructure and the second phase content of the alloy were observed and determined by scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS). The results show that there exist two different corrosion stages for 7A60 alloy in 3.5% NaCl solution, and the corrosion process can be detected by the appearance of EIS spectrum with two capacitive time constants and the wavelet fractal dimension D extracted from EN. SEM and EDS results also demonstrate that severe pitting corrosion in 7A60 alloy is mainly caused by electrochemical active MgZn2 particles, secondly by Al2MgCu and Mg2Si. Al7Cu2Fe particles make little contribution to the pitting corrosion of 7A60 alloy.
Key words: 7A60 aluminum alloy; constituent particles; pitting corrosion; electrochemical impedance spectroscopy; electrochemical noise; wavelet fractal dimension
