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], [101¯0] and [121¯0] 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) (0001)α//(101¯0)ω and [101¯0]α//[112¯3]ω between parent and product phases are observed, which differs from that previously reported for Ti. For shock compression along the [101¯0] and [121¯0] 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.