Electrochemical behavior of anodized AA7075-T73 alloys as affected by the matrix structure

A set of standard 7075-T73 alloy samples was prepared for comparison with samples that had been cold-rolled before the T73 treatment. One set of samples was subjected to cold rolling at room temperature and another deep-cooled in liquid nitrogen prior to rolling. Both sets of samples were then subjected to a T73 treatment. The microstructure of the different samples was observed and their micro-hardness was tested and recorded. The samples that had first been subjected to the deep-cooling treatment prior to rolling and T73 treatment (CRST73) showed few subgrains and smaller amounts of second phase particles in the matrix than was the case with the other two sets of samples. The experimental results also indicated that the matrix of the CRST73 samples mostly displayed disk-like precipitates of Mg ₂ Zn and Al ₂ Cu. After anodization, this batch of samples demonstrated superior corrosion resistance and the lowest passive current density during potentiodynamic polarization testing.