Electrochemical behavior of anodized AA7075-T73 alloys as affected by the matrix structure

•Cryo-rolling before solution treatment can significantly reduce the intermetallic compound particle size.•The silicon-containing lumps and air-pockets were found to be trapped in the AAO film after anodization for 15min.•The anodized samples that cryo-rolled before solution treatment performed exce...

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Bibliographic Details
Published in:Applied surface science 2013-10, Vol.283, p.249-257
Main Authors: Huang, Yung-Sen, Shih, Teng-Shih, Chou, Jun-Hung
Format: Article
Language:English
Subjects:
AAO films
Alloys
Aluminum base alloys
Anodizing
Cold rolling
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Intermetallic compound
Liquid nitrogen
Microhardness
Microstructure
Physics
Potentiodynamic polarization test
Precipitates
Precipitation
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Summary:•Cryo-rolling before solution treatment can significantly reduce the intermetallic compound particle size.•The silicon-containing lumps and air-pockets were found to be trapped in the AAO film after anodization for 15min.•The anodized samples that cryo-rolled before solution treatment performed excellent in corrosion resistance. A set of standard 7075-T73 alloy samples was prepared for comparison with samples that had been cold-rolled before the T73 treatment. One set of samples was subjected to cold rolling at room temperature and another deep-cooled in liquid nitrogen prior to rolling. Both sets of samples were then subjected to a T73 treatment. The microstructure of the different samples was observed and their micro-hardness was tested and recorded. The samples that had first been subjected to the deep-cooling treatment prior to rolling and T73 treatment (CRST73) showed few subgrains and smaller amounts of second phase particles in the matrix than was the case with the other two sets of samples. The experimental results also indicated that the matrix of the CRST73 samples mostly displayed disk-like precipitates of Mg2Zn and Al2Cu. After anodization, this batch of samples demonstrated superior corrosion resistance and the lowest passive current density during potentiodynamic polarization testing.
ISSN:0169-4332
1873-5584
DOI:10.1016/j.apsusc.2013.06.094