On the sluggish recrystallization of a cold-rolled Al-Mn-Fe-Si alloy

Annealing of supersaturated AA3xxx alloys at low temperatures usually results in sluggish recrystallization kinetics. This is due to the joint effect of the following factors: low nucleation rate, reduced grain boundary mobility, and large amount of fine precipitates (dispersoids). In this paper, samples of Al-Mn-Fe-Si alloy were appropriately homogenized in different conditions to produce different microchemistries before deformation, i.e. solutes and second-phase particles. The sluggish recrystallization behaviour of these cold-rolled Al-Mn-Fe-Si samples annealed in three different conditions was then investigated, the first condition being recrystallization without precipitation, followed by recrystallization and precipitation occurring concurrently, and finally precipitation occurring before recrystallization. The results clearly show that in all these conditions, an incubation time is involved, which decreases with increasing annealing temperature and cold deformation, as well as with decreasing solute amount. Qualitative analysis of the microstructure evolution after a sudden increase of annealing temperature suggests that the effective retarding force from solute and/or particles decreases at higher temperatures. When recrystallization occurs concurrently with precipitation, the growth of successful nuclei can still be suppressed by concurrent precipitation.