Effect of aging temperature on the intergranular corrosion properties of Al-Cu-Li alloy

Intergranular corrosion behavior in Al-Cu-Li alloys was evaluated under different aging temperatures (150 – 200 °C). Through microstructural characterization and corrosion morphology analysis, it was found that at 150 °C aging, the continuous distribution of Cu-rich particles along grain boundaries led to comprehensive intergranular corrosion. During peak aging at 175 °C, grain boundary precipitates became coarser and less continuous with the T 1 phase precipitate, significantly reducing the sensitivity to intergranular corrosion. After aging at 200 °C, the massive T1 phase precipitates inside the grains, promoting uniform corrosion and shifting the corrosion mode to pitting. At 150 °C aging, the sensitivity to intergranular corrosion was primarily influenced by Cu-rich second-phase particles. When the aging temperature increased to 175 °C and 200 °C, the sensitivity to intergranular corrosion became predominantly governed by the grain boundary precipitates and the precipitates within grains.