Shock-wave-induced grain refinement and phase state modification in coarse-grained and nanocrystalline titanium

We have experimentally studied the structure and phase variations in polycrystalline titanium stimulated by stepwise shock compression at pressures up to 40 GPa with subsequent unloading. The experiments were performed on samples of commercial titanium (VT1-0 grade) in a broad range of initial grain sizes (0.2-50 mu m). The phenomenon of grain refinement and phase composition variation in titanium under stepwise shock-wave action has been studied by transmission and scanning electron microscopy techniques. Specific features of these changes are discussed.