Influence of dislocation morphology on T1 precipitation of an Al-Cu-Li alloy

It has been known for decades that dislocation density can significantly affect the precipitation of the strengthening phases for the age-hardening alloys. However, an understanding of the relationship between dislocation morphology and their ageing precipitation is still far limited. Here we study the impacts of especially helical dislocation morphology on the T1 precipitation of an Al-Cu-Li alloy. We find that this "opened out" helical dislocation line, tailored by pulsed currents, can markedly accelerate T1 precipitation during ageing of 155 degrees C. It is also revealed that a new and beneficial dislocation configuration, formed by these heavily deformed helices, can effectively decrease the field size of interacting among T1 precursors, and the resultant enhancement in nucleation and growth of T1 phases. This study is the first to propose an innovative method, tailoring helical dislocation morphology, to accelerate ageing precipitation process. (c) 2023 Published by Elsevier B.V.