Localized corrosion study of Al 2024-T3 alloy by scanning micro reference electrode technique

The scanning microreference electrode (SMRE) technique and scanning electron microscopy (SEM) were applied to investigate the localized corrosion in its early stage of Al 2024-T3 alloy. SMRE potential measurements revealed that localized corrosion occurred on the alloy surface immediately after the exposure to 0.01 mol . L-1 NaCl solution at open-circuit potential, which was more negative than the pitting potential. The potential peaks developed with time and reached the maximum after 2 h exposure. Consequently, the heights of potential peaks would decrease and then maintained a stable value for a long time. SEM indicated the initial of localized corrosion was associated with the second phase particles, especially the Al2CuMg (S phase). Three types of corrosion behavior of S phase were observed.