Ultrafast recrystallization and grain refinement of 2A97 Al-Cu-Li alloy by electropulsing assisted annealing at lower temperature

In the current work, a pulsed current was applied on recrystallization annealing to promote the recrystallization of cold-rolled 2A97 Al-Cu-Li alloys. Besides, the effect of stored deformation energy on electropulsing assisted recrystallization was also investigated. The results indicated that, with the assistance of electropulsing, the complete recrystallization temperature of the 55 % cold-rolled alloys was decreased from 480 degrees C to 440 degrees C, and the holding time was significantly decreased from 30 min to 15 s. Moreover, the recrystallization promotion effect of electropulsing was enhanced with the increment of stored deformation energy. As the rolled reduction increased from 23 % to 55 %, the drop in complete recrystallization temperature induced by electropulsing rose from 20 degrees C to 40 degrees C. Additionally, the average grain size decreased from 46.8 mu m to 22.6 mu m, leading to an enhancement in the mechanical properties of the 2A97 alloy. The microstructure observation showed that the electropulsing assisted recrystallization was a process of nucleation and nuclei growth dominated by dislocation rearrangement, and the ultrafast recrystallization at lower temperature induced by electropulsing may be attributed to the reduction of the nucleation energy barrier and the promotion of dislocation rearrangement caused by the 'local hot spot effect' and 'electromigration effect'.