Influence of Processing States on Characteristics of Artificial Aging Precipitates in an Al-Cu-Li Alloy

Comparison of the precipitation characteristics of the Al-Cu-Li alloys under different processing states, especially in the presence or absence of thermoplastic deformation, was of little concern in previous studies. In this article, samples of an Al-Cu-Li alloy with different processing states were prepared, then the differences in precipitation behavior of these samples during 200 °C aging were examined, and the internal factors affecting the aging precipitation were also discussed. It was found that the processing states have a significant influence on precipitation dynamics and characteristics for the investigated alloy. The types of peak-aged precipitates and the density, size of the main strengthening phase show a great difference among the assessed states. Further analysis suggested that the integrated effect of dislocation and vacancy may be the internal reason that accounted for the differences in characteristics of precipitates between the cast alloy and the rolled alloy, as well as the different promotional effects of the pre-rolling and pre-stretching on precipitation of the T₁ (Al₂CuLi) phase.