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铁道科学与工程学报

JOURNAL OF RAILWAY SCIENCE AND ENGINEERING

Vol. 16    No. 6    December 2006

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Simulation on function mechanism of T1(Al2CuLi) precipitate in localized corrosion of Al-Cu-Li alloys
LI Jin-feng(李劲风), ZHENG Zi-qiao(郑子樵), REN Wen-da(任文达) , 
CHEN Wen-jing(陈文敬), ZHAO Xu-shan(赵旭山), LI Shi-chen(李世晨)

School of Materials Science and Engineering, Central South University, 
Changsha 410083, China

Abstract: To clarify the corrosion mechanism associated with the precipitate of T1(Al2CuLi) in Al-Li alloys, the simulated bulk precipitate of T1 was fabricated through melting and casting. Its electrochemical behavior and coupling behavior with α(Al) in 3.5% NaCl solution were investigated. Meanwhile, the simulated Al alloy containing T1 particle was prepared and its corrosion morphology was observed. The results show that there exists a dynamic conversion corrosion mechanism associated with the precipitate of T1. At the beginning, the precipitate of T1 is anodic to the alloy base and corrosion occurs on its surface. However, during its corrosion process, its potential moves to a positive direction with immersion time increasing, due to the preferential dissolution of Li and the enrichment of Cu. As a result, the corroded T1 becomes cathodic to the alloy base at a later stage, leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery. It is suggested that the localized corrosion associated with the precipitate of T1 in Al-Li alloys is caused by the alternate anodic dissolution of the T1 precipitate and the alloy base at its adjacent periphery.

 

Key words: Al-Cu-Li alloy; localized corrosion; mechanism; T1(Al2CuLi) precipitate

ISSN 1672-7029
CN 43-1423/U

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