A high-speed dislocation mechanism was suggested for phase transition under shock loading. At shock pressures which exceeded the equilibrium pressure of the phase transformation, shock-induced shear stresses drove the generation, motion and multiplication of partial dislocations in the initial lattice. The latter was of rocksalt-type, and comprised 2 face-centered cubic sub-lattices of ions of opposite sign. The proposed mechanism resulted in the development of an intermediate structure. This comprised 2 ionic sub-lattices of like sign: an unchanged face-centered cubic one, and a transformed base-centered orthorhombic one. There was a further transformation into the final CsCl-type structure, with 2 simple-cubic sub-lattices with ions of opposite sign. Because the unrelaxed shear stress favored easy dislocation climb, the transformation rate was very high: ranging from 1 to 3/ns for various orientations of the shocked crystal. This rate was typical of the first stage of transformation. A comparatively low (5 to 25μ/s) transformation rate, in the second stage, was attributed to a decrease in the ability of dislocations to cross the parallel glide planes and to new phase regions which impeded dislocation motion.

Dislocation Mechanism and Kinetics of Shock-Induced Phase Transformation in KCl. E.Zaretsky: Journal of Physics and Chemistry of Solids, 1998, 59[2], 253-9