The Effect of CeCl3 as an Inhibitor on the Localized Corrosion of AA2024-T3 as a Function of Temperature

Cerium inhibition of localized corrosion of AA2024-T3 as a function of temperature is evaluated based on the electrochemical characteristics of synthesized intermetallic compounds (IMCs) using a microcell method. Corrosion morphology studies of secondary phase particles in AA2024-T3 subjected to similar conditions are also presented. In a 4 mM Ce3+-containing solution, the anodic characteristics of IMCs are similar to those in a NaCl solution without any inhibitors at all temperatures tested, indicating Ce3+ is not an effective anodic inhibitor. Strong suppression of cathodic kinetics occurring on IMCs is observed in the presence of Ce3+ at all test temperatures. The inhibition efficiencies on cathodic reactions are similar at 30 and 50 degrees C, but become weaker at 70 degrees C. Electrochemical analysis indicates that inhibition provided by Ce3+ depends on the kinetics of local pH increases and the subsequent formation of Ce hydroxide on the surface, making Ce a slow inhibitor. The sluggish inhibition kinetics are amplified at high temperature (>50 degrees C). The initial dealloying corrosion of S-phase cannot be inhibited at ambient temperatures. This effect becomes more severe at high temperature (>50 degrees C). Trenching corrosion around Al-Cu-Mn-Fe type particles can be well suppressed with addition of Ce3+ at temperatures up to 50 degrees C. (C) The Author(s) 2016. Published by ECS. All rights reserved.