Anisotropic shock response of titanium: Reorientation and transformation mechanisms

We investigate shock-induced phase transformations in titanium (α-Ti) single crystals induced by shock loading along the [0 0 0 1], image and image directions using molecular dynamics simulations. We find a significant dependence of the microstructure evolution on the crystallographic shock direction, providing insight into the nature of the coupling between deformation and phase transformation. For shock along the c-axis, the orientation relationships (ORs) image and image between parent and product phases are observed, which differs from that previously reported for Ti. For shock compression along the image and image directions, there is a reorientation of the hexagonally close-packed α phase before the α → ω martensitic transformation, and the OR is consistent with the previously proposed Silcock relationship. We associate the reorientation with a shuffle and shear mechanism and suggest that shear stress is an underlying factor for the anisotropic phase transformation sensitivity.