Study on the effect of pre-deformation on the intergranular corrosion performance of Al-Cu-Li alloy

Abstract Through a systematic study involving combined pre-deformation (ranging from 0% to 6%) and aging treatment at 175 °C, the influence of precipitates on intergranular corrosion behavior was investigated. The results indicate that, in the under-aged stage, unpredeformed alloys undergo generalized intergranular corrosion due to the continuous distribution of Cu/Li-rich phases along grain boundaries. During peak aging, the uniform precipitation of the T 1 phase within grains inhibits intergranular corrosion propagation, while in the over-aged stage, the coarsening of grain boundary phases and the formation of the precipitate-free zone (PFZ) lead to a transition to pitting corrosion. Upon introducing pre-deformation at 4%-6%, high-density dislocations promote the uniform and dispersed precipitation of the T 1 phase within grains, inhibiting the aggregation of Cu-rich phases at grain boundaries and significantly reducing the tendency towards intergranular corrosion. As the level of pre-deformation increases, the corrosion mode dynamically shifts from localized intergranular corrosion to pitting corrosion. Pre-deformation improves the susceptibility to intergranular corrosion by optimizing the distribution of precipitates (dense within grains and discontinuous at grain boundaries) and balancing the potential difference between grain boundaries and grains.