Synergistic effect of Er and Si on corrosion resistance of peak-aged AlZnMgCu alloy
(1. School of Materials Science and Engineering, Taiyuan University of Science and Technology, Taiyuan 030024, China;
2. School of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China)
2. School of Materials Science and Engineering, Beijing University of Technology, Beijing 100124, China)
Abstract: The corrosion resistance and mechanical properties of peak-aged AlZnMgCu alloys containing Si and Er elements were investigated with hardness test, tensile test, intergranular corrosion test, exfoliation corrosion test and transmission electron microscopy. The results indicate that peak-aged AlZnMgCuSiEr alloy is strengthened by co-precipitation of η′ phases and nano-sized GPB-II zones. The yield strength of the AlZnMgCu alloy is increased by 38.5 MPa and the elongation is increased by 4.5%. At the same time, the corrosion resistance of the AlZnMgCuSiEr alloy is enhanced due to the synergistic effect of Er and Si. The maximum intergranular corrosion (IGC) depth decreases from 264.2 to 9.9 μm. The fundamental reason is that the co-addition of Si and Er regulates the evolution of precipitated phases in grains and at grain boundaries.
Key words: AlZnMgCu alloy; GPB-II zones; intergranular corrosion; exfoliation corrosion; mechanical properties