General Corrosion Behavior of Pure Copper with Optimized Structure Based on Grain Boundary Engineering

The corrosion behavior of copper (M1) samples in the as-received state, after recrystallization and after structure optimization based on grain boundary engineering was investigated using polarization tests in a specially non-aerated 0.1 M NaCl solution. The general view, morphology, chemical and phase composition of the corrosion products formed on the samples surface during polarization tests were investigated using scanning electron microscopy, energy dispersive and X-ray diffraction analysis. It was established that optimization of the structure in two thermo mechanical treatment modes—TMT I and TMT II—leads to a consistent increase in the overall corrosion resistance of the samples compared to the recrystallized state of copper. The increase in corrosion resistance of copper is consistent with increase in the proportion of special twin boundaries resistant to corrosion and a decrease in the proportion of random high-angle boundaries susceptible to corrosion during TMO I and TMO II. The features in the cathode region of the polarization curve and in the general view and morphology of the corrosion products for copper samples after TMO II allow us to assume a qualitative change in the nature of their overall corrosion in comparison with other studied samples.