Achieving outstanding combination of strength and ductility of the Al-Mg-Li alloy by cold rolling combined with electropulsing assisted treatment

Abstract

Outstanding combination of strength and ductility of the Al-Mg-Li alloy could be achieved using the efficient and energy saving route of cold rolling combined with two steps of electropulsing assisted treatment (EAT), namely, the electropulsing assisted recrystallization annealing (EARA) and electropulsing assisted ageing (EAA). It was found that the EARA tremendously promoted the recrystallization behavior of the cold rolled alloy, leading to the grain refinement and texture weakening. Besides, the following EAA accelerated the coarsening of the strengthening δ′ phase. As a result, there was a remarkable improvement in strength and ductility, among which the increase in strength was mainly due to the combined effect of precipitation of δ′ phase and grain refinement, while the increase in elongation was mainly attributed to the grain refinement and texture modification. The rapid recrystallization during EARA was substantially attributed to the promotion effect of electropulsing on dislocation climb, which further resulted from not only the higher diffusion coefficient of vacancies under the application of electropulsing but also the another diffusion flux of vacancies induced by electro-migration. Keywords: Al-Mg-Li alloy, Electropulsing assisted treatment, Microstructure evolution, Mechanical properties