Intergranular Corrosion and Exfoliation Corrosion Behaviors of 2197 Al-Li Alloy with Different Aging Treatments

The intergranular corrosion and exfoliation corrosion behaviors of 2197 Al-Li alloy with T6 temper and T8 temper were investigated.The results show that with the increase of aging time,the number of T1 phase and precipitate-free zone(PFZ) at grain boundaries increased,and the susceptibility to intergranular corrosion and exfoliation corrosion was enhanced.The corrosion resistence of the alloy under T8 condition was better than that under T6 condition,because lower aging temperatured and pre-deformation prior to aging promoted T1 phase precipitation and minimize PFZ at grain boundaries.The susceptibility to exfoliation corrosion estimated by the electrochemical impedance spectruscopy(EIS) was the same as the one estimated by exfoliation photograph observesion.