Deformation and mechanism of {10–11} twinning in cryo-rolled fine-grained α-titanium

• Rare {10–11} compression twinning is activated in commercially pure titanium through precise initial texture control during single-pass cryogenic rolling at low strain levels. • The activated twins exhibit pronounced non-Schmid behavior where variant selection is governed by local stress concentrations rather than the global macroscopic stress state. • A dual mechanism is elucidated wherein the dissociation of pyramidal dislocations provides the energetic driving force for nucleation while high geometric compatibility with slip systems facilitates twin growth. Activating rare twinning modes has emerged as an effective strategy for tailoring the mechanical properties of hexagonal materials; however, experimentally inducing specific variants such as the {10–11} twin remains challenging. This study systematically investigates the formation mechanism of the rare {10–11} compression twin in fine-grained commercially pure Ti during cryogenic rolling at 77 K. Electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) analyses reveal that the initial crystallographic texture largely dictates twinning activity. With increasing deviation of the {0001} axis from the rolling direction, the activity of conventional {11–22} twinning is progressively suppressed, while the occurrence of {10–11} twinning becomes increasingly prevalent, accounting for approximately 8.8% of the twin boundary length at a strain of 5%. Notably, these {10–11} twins exhibit pronounced non-Schmid behavior, as evidenced by a low average Schmid factor of approximately 0.14. Dislocation analysis reveals a dual-mechanism pathway governing twin nucleation and growth: pyramidal 〈c + a〉 dislocations dissociate to supply the necessary c-axis shear for nucleation, while a high slip–twin geometric compatibility ( m’ > 0.85) promotes twin propagation. These results provide mechanistic insights into the nucleation-to-growth evolution and identify twinning-based modification as an effective strategy for achieving a favorable strength–ductility synergy in cryogenic environments.