Combining the Electrochemical Microcell Technique and the Electron Backscatter Diffraction method to study the electrochemical behaviour of polycrystalline aluminium in sodium chloride solution

Abstract

The corrosion behaviour of pure aluminium was studied at the microscale in 0.1M NaCl by combining the electron backscatter diffraction technique and the electrochemical microcell technique. The microstructure was first described. It was found that plastic strain has little influence on these microstructural parameters. After surface preparation, the crystallographic orientation of grains plays a significant role in their corrosion behaviour. Grains oriented along (001) planes are the most resistant to pitting corrosion whereas those oriented along (111) planes are the most susceptible to pitting. After plastic deformation, the susceptibility to pitting corrosion of Al grains is significantly increased and there is no influence of the crystallographic orientation of grains. It was proposed that the presence of a high density of statistically stored dislocations (which cannot be detected by EBSD) affects the physical chemical properties of the oxide film formed on grains. This oxide film degenerates, leading to high susceptibility of pure Al to pitting corrosion.