Deformation Behavior of Commercially Pure Titanium Subjected to Blast Assisted Deformation: New Insights on {11-21} Extension Twinning

In the present work, the microstructure and texture evolution in commercially pure titanium subjected to blast assisted deformation has been investigated by means of electron backscattered diffraction and transmission electron microscopy. The evolved texture in the deformed material is primarily attributed to the dominant ⟨1010⟩ 64.4° contraction twinning. Other deformation twins were also observed in a low fraction. A uniform dislocation background with other microstructural features observed suggested the formation of a superimposed microstructure in the material. {1121} extension twins (ET2) with a thick uniform pile-up of dislocation along its boundary have formed in the material. Parts of ET2 have detwinned leaving gaps along the twin length, revealing the unstable nature of ET2 twins. The in-depth microstructural analysis reveals the ET2 twin formation mechanism, where the instability developed in the material due to progressive lattice rotation via accumulative slip is relieved by ET2 twin formation by atomic shuffling. The gaps (local detwinning) observed in the present case is attributed to the transient oscillatory response of the material under impulsive loading, which has been previously reported in the literature.