Inhibition of AA2024-T3 on a Phase-by-Phase Basis Using an Environmentally Benign Inhibitor, Cerium Dibutyl Phosphate

Abstract

Inhibition of anodic and cathodic reactions on intermetallic compounds in aluminum alloy 2024-T3 (Al-4.4Cu-1.5Mg-0.6Mn) by cerium dibutyl phosphate [Ce(dbp)_3] additions to dilute chloride solutions was studied using a microelectrochemical cell approach. Cathodic polarization curves were measured on Al_2Cu, Al_7Cu_2Fe, Al_20Cu_2Mn_3, and Al_3Fe. Results showed the Ce(dbp)_3 effectively inhibits oxygen reduction on each phase. Anodic polarization curves were measured for Al_7Cu_2Fe and Al_2CuMg compounds. Results showed that Ce(dpb)_3 additions stabilized passivity of these phases. This work suggests that Ce(dbp)_3 may effectively inhibit localized corrosion owing to its mixed nature, providing retardation of the oxygen reduction reaction upon noble intermetallics and concomitant retardation of dissolution of phases that may be prone to attack.