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 structure and on the recrystallization kinetics is noted. It is found experimentally that the incubation period for static recrystallization in single-crystal KCl:0.05wt %Sr2+ is shortened and recrystallization takes place at room temperature after deformation in this temperature range. Here, during the new recrystallization grains have a twinned orientation with respect to the initial single crystal during the first stage and to the subgrains of the deformed crystal. As the annealing temperature is raised, the stage in which twins grow in KCl:0.05wt %Sr2+ crystals is shortened and it is displaced by recrystallization through migration of high-angle grain boundaries of the common type. Deformation conditions which ensure prolonged (at least three 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].