Corrosion behavior of aluminum alloys in Na2SO4 solution using the scanning electrochemical microscopy technique

The corrosion behavior of aluminum alloys 1060 and 2A12 in a 10 mM Na2SO4+5 mM KI solution was investigated by scanning electrochemical microscopy(SECM) and scanning electron microscopy(SEM) . The potential topography and corrosion morphology results show that the potential of the sample surface over the same area changes with the increase of immersion time. The corrosion area becomes large,and the potential becomes more negative. The corrosion potential of the 2A12 alloy surface is lower than that of 1060 aluminum,and 2A12 alloy becomes easily corrosive. This is the reason that preferential dissolution in the boundary region of some intermetallic particles(IMPs) occurs and different dissolution behaviors are associated with different types of IMPs because of different potentials.