ISSN: 1003-6326
CN: 43-1239/TG

Vol. 31    No. 8    August 2021

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Correlations among stress corrosion cracking, grain-boundary microchemistry, and Zn content in high Zn-containing Al-Zn-Mg-Cu alloys
Ding-ling YUAN1,2, Song-yi CHEN1,2, Kang-hua CHEN1,2,3, Lan-ping HUANG1,2, Jiang-yu CHANG1,2, Liang ZHOU1,2, Yun-feng DING2,3
(1. Light Alloy Research Institute, Central South University, Changsha 410083, China;
2. Collaborative Innovation Center of Advanced Nonferrous Structural Materials and Manufacturing, Central South University, Changsha 410083, China;
3. National Key Laboratory of Science and Technology for National Defence on High-Strength Lightweight Structural Materials, Central South University, Changsha 410083, China
Abstract: The correlations among the corrosion behaviour, grain-boundary microchemistry, and Zn content in Al-Zn-Mg-Cu alloys were studied using stress corrosion cracking (SCC) and intergranular corrosion (IGC) tests, combined with scanning electron microscopy (SEM) and high-angle angular dark field scanning transmission electron microscopy (HAADF-STEM) microstructural examinations. The results showed that the tensile strength enhancement of high Zn-containing Al-Zn-Mg-Cu alloys was mainly attributed to the high density nano-scale matrix precipitates. The SCC plateau velocity for the alloy with 11.0 wt.% Zn was about an order of magnitude greater than that of the alloy with 7.9 wt.% Zn, which was mainly associated with Zn enrichment in grain boundary precipitates and wide precipitates-free zones. The SCC mechanisms of different Zn-containing alloys were discussed based on fracture features, grain-boundary microchemistry, and electrochemical properties.
Key words: Al-Zn-Mg-Cu alloy; stress corrosion cracking; Zn content; grain-boundary microchemistry
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
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