Anisotropic shock response of titanium: Reorientation and transformation mechanisms

Abstract We investigate shock-induced phase transformations in titanium (α-Ti) single crystals induced by shock loading along the [0 0 0 1], [ 1 0 1 ¯ 0 ] and [ 1 2 1 ¯ 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) ( 0 0 0 1 ) α / / ( 1 0 1 ¯ 0 ) ω and [ 1 0 1 ¯ 0 ] α / / [ 1 1 2 ¯ 3 ] ω between parent and product phases are observed, which differs from that previously reported for Ti. For shock compression along the [ 1 0 1 ¯ 0 ] and [ 1 2 1 ¯ 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.