Correlation of intergranular corrosion behaviour with microstructure in Al-Cu-Li alloy

• Published in: Corrosion science 2018-07, Vol.139, p.215-226
• Main Authors: Huang, Jia-lei, Li, Jin-feng, Liu, Dan-yang, Zhang, Rui-feng, Chen, Yong-lai, Zhang, Xu-hu, Ma, Peng-cheng, Gupta, Rajeev Kumar, Birbilis, Nick
• Format: Article
• Language: English
• Subjects: Aluminium; Aluminum alloys; Aluminum base alloys; Circuits; Copper; Corrosion; Grain boundaries; Heat treating; Heat treatment; Intergranular corrosion; Intergranular corrosion (IGC); Microstructure; Morphology; Open circuit potential (OCP); Predeformation; TEM
• ISSN: 0010-938X; 1879-0496
• DOI: 10.1016/j.corsci.2018.05.011

•Increasing ageing temperature and predeformation caused acceleration in the evolution of corrosion mode.•The corrosion mode in AA1460 evolved from intergranular to intragranular.•The precipitation of δ′(Al3Li) and T1 (Al2CuLi) in AA1460 resulted in a lower value of open circuit potential.•A relationship between open circuit potential and corrosion mode was presented. The IGC behaviour, OCP and microstructure of AA1460 (Al-3.12Cu-2.14Li-0.12Sc-0.12Zr, in wt.%), following HT1 (heat treatment without predeformation) and HT2 (heat treatment with predeformation) tempers were investigated. Both δ′ (Al3Li) and T1 (Al2CuLi) phases were precipitated within grains during heat treatment, while T1 phase also precipitated in the vicinity of grain boundaries. The evolution of inter- and intra-granular microstructures in AA1460 influenced the local and global electrochemical characteristics, which in turn influenced the temper dependent corrosion morphologies of AA1460. A correlation between OCP and corrosion mode was proposed, which may be used to compare the IGC sensitivity of AA1460 with different tempers.