Shock-Induced Phase Transformation in Cadmium Sulfide Dispersed in an Elastomer

摘要

The study of structural phase transitions under dynamic high pressures produced by shock loading is an area of considerable interest. In general, crystal structures cannot be observed directly in shock-wave experiments, and comparisons with static high-pressure data are needed to interpret and understand shock-wave results. One of the factors that complicates such comparisons is the ability to account for the role of stress deviators in shock-wave experiments, particularly, for materials that may display large strength. The effects of stress deviators or shear stresses are not easily incorporated in the thermodynamic analysis of shock-induced phase changes in solids. Shock-wave response of cadmium sulfide powder has been examined by conducting impact experiments on cadmium sulfide/elastomer composites. Particle-velocity profiles at different sample depths were measured in experiments ranging from 7 to 45 kbar. Although no two-wave structure was observed in the wave profiles, the peak pressure-volume states and the wave-velocity results indicate a shock-induced phase transformation in the cadmium sulfide. Calculations based on a simple mixture model constructed from the hydrostatic data on cadmium sulfide and shock data on the elastomer are in good agreement with the experimental results. Reasons for the good agreement between the shock data and the hydrostatic results are attributed to nearly hydrodynamic compression of the cadmium sulfide particles because of the elastomer matrix. Reprints. (AW)