RECRYSTALLIZATION NUCLEATION AND GRAIN GROWTH IN Al-1wt.Mn SINGLE CRYSTALS OF STABLE ORIENTATIONS

摘要

The crystallographic aspects of recrystallization nucleation have been characterized in Al-1%wt. Mn single crystals of Goss{110}<001> and brass{110}<112> orientations. Samples were compressed 40% and then lightly annealed to partial recrystallization. SEM/EBSD orientation maps revealed that boundaries with misorientation angles above 8° are not present in the deformed structures. During annealing high angle boundary segments (>15°) were created at an advanced stage of recovery preceding grain nucleation, i.e. some of the low-angle boundaries evolve into high-angle boundaries. As the dislocation-free subgrains are now partly or completely surrounded by high-angle boundaries, the orientations of nuclei are different from the orientations of their deformed/recovered neighbours. There is also a strong relation between as-deformed orientations and the limited number of recrystallized grain orientations. The results are discussed in terms the creation of twist or tilt grain boundaries of high misorientation by thermally activated, co-ordinated movement of dislocations during recovery.