Recovery Kinetics in High Purity and Commercial Purity Aluminium Alloys

Utilizing the electron backscatter diffraction (EBSD) technique, orientation dependent sub-grain growth was characterized with respect to grain size and average boundary misorientation. In the high purity alloys, small additions of Mn in solid solution slowed down the recovery kinetics. The recovery mechanisms were however not altered, but recovery kinetics were found to be orientation dependent. The presence of high angle grain boundaries or transition bands, i.e. large and shall) orientation gradients, seemed to change the growth from slow and continuous to a faster and discontinuous process. This was typical for Cube and Goss, while weak, short or long range orientations gradients observed in Copper, S and Brass, did not alter growth which was slow and continuous. Preliminary results on a commercially pure alloy indicate that iron in solid solution is dramatically slowing down the softening kinetics but can form clusters by an intermediate annealing in order to speed up recovery.