关键词: Al合金, 局部腐蚀, 微Cl-复合电极, 表面Cl-浓度分布

Abstract: Micro combination Ag/AgCl electrode with a tip measuring tens micron in diameter was fabricated. The probe satisfied in situ imaging of Cl - distribution at metal surface in chloride solution because of its excellent linearity between potential and Cl - concentration, rapid response, good stability and selectivity. With the aid of the home made Micro Electrode Scanning system and scanning Cl - probe, the effect of the [Cl - ] at 2024_Al/solution interface on localized corrosion process was investigated. It was demonstated directly that Cl - ion in solution immigrated toward, then adsorbed preferentially and accumulated at the junction between the Al_Cu_Mg secondary phase and Al matrix, the uneven distribution of Cl - accelerated the initiation and development of localized corrosion of 2024_al alloy in Cl - containing solution.