Interaction of recrystallization and precipitation: The effect of Al3Sc on the recrystallization behaviour of deformed aluminium

The kinetics and mechanisms of recrystallization in high purity binary Al-Sc alloys have been investigated. In an Al-0.25wt.%Sc alloy, precipitation always precedes recrystallization, which is severely inhibited. However, in an Al-0.12wt.%Sc alloy, precipitation is found to either precede, follow or occur concurrently with recrystallization, depending on the processing conditions, and the resultant complex microstructures are interpreted in terms of the interactions between precipitation and recrystallization. Coherent precipitates are found to coarsen and become semi-coherent during the passage of low-angle boundaries during recovery. The passage of high-angle boundaries through semi-coherent precipitates during recrystallization occurs by migration of the boundary through the particle, resulting in the precipitates maintaining semi-coherency with the new grain.