Electrochemical passive properties of AlxCoCrFeNi (x = 0, 0.25, 0.50, 1.00) alloys in sulfuric acids

This study investigates the electrochemical passive properties of AlxCoCrFeNi alloys in H2SO4 by potentiodynamic polarization, EIS, and weight loss tests from 20 to 65 °C. Experimental results indicate that Al harms the corrosion resistance in H2SO4 at temperatures exceeding 27 °C owing to the porous and inferior nature of the protection oxide film of Al in these alloys. Closely examining the Arrhenius plots of corrosion current density reveals that both pre-exponential factor A and activation energy Ea increase with Al content. However, A affects corrosion current density more significantly than Ea at higher temperatures and, conversely, at lower temperatures.