In-situ observations of dislocation recovery and low angle boundary formation in deformed aluminium

An experimental study of the recovery of dislocations and low angle boundary formation in aluminium is presented. By combining in-situ annealing with orientation mapping in the transmission electron microscope, maps of geometrically necessary dislocation estimates derived from orientation measurements and subgrain formation can be quantitatively analysed. A thin foil of a commercially pure aluminium alloy cold-rolled to a true strain of ε = 2.3 and annealed in-situ in four steps of increasing temperatures from 170 °C to 560 °C was studied. An increase in the subgrain size and low angle boundary misorientation was accompanied by a halving of the dislocation density from 1.2 × 1016 m−2 to 0.6 × 1016 m−2. Limited boundary migration was observed and the increased subgrain size was attributed to the dissolution of dislocations within the low angle boundaries upon annealing