The shock loading of polycrystalline beryllium: residual microstructure and the effects of microstructure in internal spallation

The residual microstructure of polycrystalline beryllium in both a rolled-reduced and hot-pressed form has been characterized by transmission electron microscopy following shock deformation at pressures up to 9.2 kbar, and the observation of residual shock softening was attributed to the activated-glide response of sub-grain boundaries to the shock wave passage. A marked difference in the shock-induced spallation in the roll-reduced material as compared with the hot-pressed material has been attributed to a difference in the density of grain-boundary ledge structure which induces larger spall cracks with a greater frequency when the density and size of the ledges is large. (author)