Unraveling the Role of Copper on the Corrosion Behavior of Fe-20Cr-xCu Alloys in 3.5% NaCl Solution

This study systematically investigates the impact of copper (Cu) incorporation on the microstructure and corrosion resistance of newly developed ferritic stainless-steel alloys in NaCl environment. The study has utilized conventional advanced microelectrochemical techniques such as scanning electrochemical microscopy (SECM), to gain detailed insights into localized corrosion characteristics of Fe-20Cr-xCu (x = 0, 2, 4 wt.%) alloys. Potentiodynamic polarization (PDP) analysis revealed that Fe-20Cr-2Cu alloy exhibited more noble E_corr (− 215.55 mV versus SCE )_, lowest i_{corr (}0.0069 µA cm^{− 2}), lowest i_pass (0.0001 A cm^{− 2}) and highest pitting potential (23.658 mV versus SCE), indicating its enhanced corrosion resistance. Dynamic EIS measurements confirmed the enhanced electrochemical stability of the Fe-20Cr-2Cu alloy, suggesting the growth of a dense and robust passive layer. Scanning electrochemical microscopy (SECM) results further confirmed the sustained stability of this alloy after 24 hr. exposure, revealing a uniform surface with minimal heterogeneity. The obtained results corroborate that the addition of 2 wt.% Cu is the optimal alloying concentration for improving the corrosion resistance of newly developed Fe-20Cr-xCu alloys.