Activation of contraction twins during compression and related texture characteristics in α-titanium

Abstract

This work demonstrates that axial compression along 0002and101¯0 in individual grains of α-Titanium can effectively activate up to six variants of 112¯2112¯3¯ contraction twins (CT). Compression parallel to 101¯0 primarily introduces 101¯2101¯1¯ type extension twins (ET), orienting the c-axis almost along the compression axis. Further compression activates up to six 112¯2112¯3¯ CT variants, each with a specific orientation having Euler angles of (0°−60°+n60°, 63.5°, 30°), where n is the sequence number of the CT variant. All six CT variants may not be activated during uniaxial compression due to the deviation of the parent grains' c-axis from the compression direction (CD) and deformation heterogeneities. The nucleation and interaction of CT variants lead to the formation of coincident site lattice boundaries with characteristics (θ−uvtw) angle axis pair of 63.5°101¯0−∑7b, 51.2°11¯00−∑23a, 60°112¯1−∑19b, and 77.3°18¯70−∑17b. The activation of multi CT variants and their interaction can contribute to grain fragmentation and texture weakening. From statistical analyses, the nucleation and growth of CT variants appeared to follow the Schmid law. However, deviations from the Schmid behavior occurred by the activation of low Schmid factor CT variants and could be attributed to slip and twin activities in neighbor grains.