Influence of the Microstructure on the Corrosion Behavior of Brazed Al-layers

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Abstract

Aluminium alloy is widely used in the industry, while aluminium brazing sheets are mainly applied in heat-exchanger. The corrosion mechanism and corrosion behaviors have been studied in recent years. The aim of this thesis is to explore the difference of corrosion performance and microstructure at the distinguished regions in two specific systems - alloy FAB913 and alloy 8125. The samples were etched by GDOES sputtering in order to evaluate the corrosion performance at different depths. Electrochemical and SKPFM experiments were carried out to elucidate the differences in corrosion rate and surface potential. Furthermore, the microstructure changes after corrosion were observed by SEM analysis. The results indicate that the re-solidified clad surface was susceptible to localized corrosion attack while the heat affected area and diffusion zone show good corrosion performance. Furthermore, the Cu- and Si- content played a crucial role in the corrosion resistance of the alloys.