Sequential {101¯2} twinning stimulated by other twins in titanium

Abstract

We experimentally studied sequential {10 2} twinning in rolled pure titanium at room temperature and identified a new sequential twinning mechanism, i.e., {10 2} () extension twin stimulated by the twin-twin junction of two primary {11 } extension twins and , which holds a certain relation . Schmid factor analysis, as the local stress is taken into account, is able to determine the position of sequential twin variant, but cannot determine the twin variant. Displacement gradient accommodation is used to determine the twin variant. The well-known secondary {10 2} () extension twins in primary {11 2} () contraction twins (referred to as  double twinning) are also analyzed according to a generalized Schmid factor analysis. Displacement gradient accommodation and twin nucleation based on dislocations dissociation only work well for the most active twin variants, but cannot address other phenomena associated with  double twinning. For rarely activated twin variants, displacement gradient accommodation was not satisfied.

Interface structures and twinning mechanisms of twins in hexagonal metals

“…In an elastic equilibrium point of view, the internal stress inside twins is different than in the surrounding medium. The resulting internal stress in the surrounding medium intrinsically prevents the twin from growing [101,102]. But it does not change twinning mechanisms.…”

Formation of slip bands and microstructure evolution of Ti-5Al-5Mo-5V-3Cr-0.5Fe alloy during warm deformation process

“…The pure titanium (hexagonal close-packed structure, HCP) is mainly dominated by twining mechanism [9], while it has been reported that the deformation modes in the β…”

Microstructure Evolution of Commercial Pure Titanium During Interrupted In Situ Tensile Test

“…[10] C 4 -T 5 is the dominant double twin in G1. Indeed, the formed 11 22-10 12 double twins in a-Ti always follow the C i -T i /T i+1 group proposed by Xu et al [30] The T i /T i+1 variants are activated to accommodate the local shear of primary C i twin. To further investigate the variant selection between T i and T i+1 variant, the accommodation capacity on C i twinning is compared by transforming the D t of all the C 4 , T 4 , and T 5 into the crystal frame of C 4 .…”

“…[29] Twins accommodated by the twins in neighboring grain have a great capacity to develop into large size. [22] Indeed, there appears adjoined twin to active large C 4 in the upside neighboring grain (G5), the [30]. By the method of displacement gradient accommodation (DGA) criterion, they suggested that the C i -T i /T i+1 double twins are the most predominant because the T i /T i+1 variants have the highest capacity to accommodate the primary C i twin.…”