Effects of Silver on the Strength in the T8 Condition and the Heat Resistance of Al–Cu–Li–Sc Alloy

Silver (Ag) is widely used in commercial Al–Cu–Li alloys to enhance their mechanical performance. However, this study reveals a paradoxical effect of Ag incorporation in an Al–Cu–Li–Sc alloy. Ag significantly improves the strength of Al–Cu–Li–Sc alloy in the T8 condition, but it simultaneously compromises its heat resistance. This negative impact is primarily due to the formation of excessive Ag‐ and Cu‐containing phases, such as Al ₆ CuLi ₃ ‐T ₂ phase and irregular high‐contrasting phases, which are promoted by the presence of Ag and thus leading to a reduction in the coarsening resistance of T1 precipitates (Al ₂ CuLi phase). The study further demonstrates that higher thermal exposure temperature and increased Ag content exacerbate this adverse effect. This research clarifies the dual role of Ag and offers valuable insights for the compositional design of heat‐resistant Al–Cu–Li–Sc alloys, depending on the specific service conditions.