Effect of creep ageing on the corrosion behaviour of an Al-Cu-Li alloy

Creep ageing of Al-Cu-Li alloys induces precipitation of T1(Al2CuLi) and a high fraction of low-angle grain boundaries (LAGBs) and dislocations in grain interior, factors potentially contributing to corrosion. Qualitative/quantitative analysis of precipitates and quasi-in-situ EBSD observations of stress free and stress added alloy reveal that fine dense precipitation of T-1 in grain interior and suppressed precipitation along grain/subgrain-boundary induced by stress adding make the corrosion mode evolve from intergranular to intragranular, and grain orientation displays as the most relevant metallurgical parameter for the localised corrosion although the fraction of LAGBs and dislocations have been greatly improved by stress loading.

Automated summary

Creep ageing of Al-Cu-Li alloys leads to precipitation of T1 and a high fraction of low-angle grain boundaries and dislocations which contributes to corrosion. Stress-induced fine dense precipitation of T-1 in grain interior and suppressed precipitation along grain/subgrain-boundary shift corrosion mode from intergranular to intragranular.