Enhanced SCC resistance of 7056 aluminium alloy by Y and Si additions

Abstract

The effect of Y and Si additions on the microstructure and stress corrosion cracking (SCC) of the high Zn-containing 7056 aluminium alloy has been investigated. The morphology and composition of dispersions were analysed by transmission electron microscope equipped with super-X energy disperse spectroscopy. The SCC resistance was measured by a double-cantilever beam experiment. Results indicated that the SCC resistance was significantly improved by the mixed Y and Si additions, which can mainly be attributed to the reduction in the recrystallisation fraction and the increase in the sub-grain boundaries fraction caused by the high coherent (Al,Si)₃(Zr,Y) dispersions and another important reason was the formation of the Y–Si-containing oxide film with the higher compactness and electrochemical impedance.

KEYWORDS:

• 7056 aluminium alloy
• stress corrosion cracking
• rare-earth Y element
• Si element
• recrystallisation
• passivation film

Acknowledgements

Liang Zhou: Conceptualisation, Investigation, Data curation, Writing – original draft, Funding acquisition. Zhiyong Sheng: Investigation. Qiang Liu: Investigation. Ligang Xin: Investigation. Kanghua Chen: Funding acquisition. Songyi Chen: Funding acquisition, Writing.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability

The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of a continuing study.

Additional information

Funding

This research was supported by Hunan InnoChina Advanced Materials Co., Ltd. (grant number ZJ2021-YJ-001), National Key Laboratory of Science and Technology for National Defence on High-Strength Lightweight Structural Materials of China (grant number 20190104), National Key Research and Development Program of China (grant number 2016YFB0300801), Natural Science Foundation of Hunan Province of China (grant number 2018JJ3645), Graduate Free Exploration and Innovation Project of Central South University of China (grant number 2018zzts152), State Key Laboratory of High Performance Complex Manufacturing of Central South University of China (grant number ZZYJKT2020-03).