Corrosion behavior of ultrafine-grained copper processed by equal channel angular pressing in simulated sea water

The corrosion behavior of copper fabricated by equal channel angular pressing and further annealing was systematically investigated in 3.5 wt% NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy, and weight loss method. Microstructure and corroded surface morphologies were observed by electron backscattered diffraction and scanning electron microscopy, respectively. Results indicated that ultrafine-grained copper had much lower corrosion current density and corrosion rate than annealed coarse-grained counterparts. Transition from uniform to intergranular mode of corrosion happened, which can be attributed to the dominance of two times larger volume fraction of high angle grain boundaries formed during annealing process.