Influence of Zn contents on precipitation and corrosion of Al-Mg-Si-Cu-Zn alloys for automotive applications

• Published in: Journal of alloys and compounds Vol. 778; pp. 256 - 270
• Main Authors: Guo, M.X., Du, J.Q., Zheng, C.H., Zhang, J.S., Zhuang, L.Z.
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 25.03.2019; Elsevier BV
• Subjects: Al-Mg-Si-Cu-Zn alloys; Aluminum base alloys; Copper base alloys; Copper zinc alloys; Corrosion; Grain boundaries; Grain boundary precipitation; Intergranular corrosion; Intragranular precipitation; Magnesium; Precipitation-free zones; Silicon; Zinc; Al-Mg-Si-Cu-Zn alloys; Grain boundary precipitation; Precipitation-free zones; Intergranular corrosion; Intragranular precipitation
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.11.146

We report on a study of the effect of Zn contents on the intragranular and grain boundary precipitation and corrosion behavior of Al-Mg-Si-Cu-Zn alloys. Our results show that with increasing Zn content, peak hardness and intragranular precipitation kinetics of the alloys are enhanced, whereas grain boundary precipitation is negatively affected. The complex interactions that occur between intragranular and grain boundary precipitation lead to differences in intergranular corrosion susceptibility for different aging conditions. Our results provide fundamental insight into the intergranular corrosion response in aged Al-Mg-Si-Cu alloys, as a function of Zn contents. [Display omitted] •Both the age hardening response and peak hardness of the aged Al-Mg-Si-Cu-Zn alloys increase with increasing Zn content.•The effect of Zn contents on the intragranular and grain boundary precipitation of Al-Mg-Si-Cu-Zn alloys was studied.•The effect of Zn contents on the corrosion of Al-Mg-Si-Cu-Zn alloys in the different aged conditions was studied.•Intergranular corrosion mechanisms in the two-step aged Al-Mg-Si-Cu alloys with different Zn contents were established.