中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 33 No. 7 July 2023 |
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. Key Laboratory of Non-ferrous Metals Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
3. National Key Laboratory of Light and High Strength Structural Materials, Central South University, Changsha 410083, China;
4. School of Metallurgy and Environment, Central South University, Changsha 410083, China）
Abstract:The effect of Cu content on intergranular corrosion (IGC) and exfoliation corrosion (EXCO) susceptibility of Al-Zn-Mg-(Cu) alloys was investigated by electrochemical test, immersion test, electron backscattered diffraction, optical microscope, scanning electron microscope, scanning transmission electron microscope and scanning Kelvin probe force microscope. As Cu content increases from 0 to 2.6 wt.%, IGC susceptibility increases, while EXCO susceptibility first increases and then decreases, reaching the maximum at Cu content of 1 wt.%. With the increase of Cu content, the area fraction of recrystallized grains increases, and the aspect ratio of recrystallized grains first decreases and then increases; moreover, the Volta potential difference between grain boundary precipitates (GBPs) and the matrix increases, making GBPs more susceptible to corrosion. The initiation and propagation of IGC and EXCO are discussed mainly based on the features of GBPs, grain structure, and the Volta potential difference between GBPs and the matrix.
Key words: copper; intergranular corrosion; exfoliation corrosion; Al-Zn-Mg-Cu alloy; scanning Kelvin probe force microscope
