Recrystallization of pure and strontium-doped KCl crystals

The kinetics of microstructure transformations are studied during annealing of deformed single crystals of KCl and KCl:0.05wt%Sr2+ at temperatures of (0.35-0.55)T-m (where T-m is the melting temperature) and during storage at room temperature. The effect of deformation rates ranging from 0.01 mm/min to 0.1 mm/min at a deformation temperature T-d = 0.5T(m) on the crystal st ructure and on the recrystallization kinetics is noted. It is found experim entally that the incubation period for static recrystallization in single-c rystal KCl:0.05wt %Sr2+ is shortened and recrystallization takes place at r oom temperature after deformation in this temperature range. Here, during t he new recrystallization grains have a twinned orientation with respect to the initial single crystal during the first stage and to the subgrains of t he deformed crystal. As the annealing temperature is raised, the stage in w hich twins grow in KCl:0.05wt %Sr2+ crystals is shortened and it is displac ed by recrystallization through migration of high-angle grain boundaries of the common type. Deformation conditions which ensure prolonged (at least t hree months) stability of the post-deformation hardening of single crystals are found experimentally for Sr2+-doped deformed single crystals. (C) 1999 American Institute of Physics. [S1063-7834(99)01402-1].