Lateral stress and shear strength measurements in polycrystalline potassium chloride, above and below the B1/B2 phase transition during shock loading

Manganin stress gauges have been placed in potassium chloride plates, in such orientation that they are sensitive to the lateral component of stress during shock loading. At ∼2 GPa, this material undergoes a dynamic phase change from the B1, NaCl structure under ambient conditions to the B2 CsCl structure. Impact conditions were chosen such that measurements were made both above and below this stress. In combination with known longitudinal stresses, the shear strengths were determined and plotted as a function of impact stress. In the low pressure phase, it would appear that shear strength is constant or only increases marginally, while at higher stresses, strengthening is clearly observed. Both observations are discussed in terms of dislocation motion, generation, and storage.