Localized corrosion evolution associated with intermetallic particles in Al-Cu-Li alloys

Microstructure and corrosion behaviour associated with intermetallic particles (IMPs) in 2A97 Al-Cu-Li alloys of different thermomechanical conditions are characterized by a wide range of electron microscopy techniques in the present work. Three distinctive corrosion phenomena associated with IMPs are observed, including trenching, de-alloying and Cu re-distribution. Micro-galvanic interaction between IMPs and the peripheral matrix results in trenching, which may develop unevenly depending on stored energy distribution. Selective dissolution of more active elements also occurs to IMPs, which may result in de-alloyed bands related to stacking faults. The de-alloyed remnants further promote the re-distribution of Cu, which not only benefits the propagation of trenching, but may also contribute to the initiation of stable localized corrosion.