K. Hamulka; T. Vermeij; A. Sharma; R. Pero; J. Michler; X. Maeder
Acta Materialia 306 (2026) 121923
The plastic deformation behavior of high-purity alpha-titanium (α-Ti) single crystals is investigated through micropillar compression experiments over a wide range of strain rates (10−3 to 103 s−1) at room temperature. For c – axis compression, where prismatic slip is geometrically unfavorable, two distinct deformation regimes emerge. At low to intermediate strain rates (ε̇ < 102 s−1) plasticity is governed by a non-classical kink band-type mechanism. Deformation is accommodated within broad, localized bands exhibiting significant continuous lattice rotation and internal 〈c +a〉 dislocation structures. These bands lack discrete slip traces and show features distinct from conventional slip or twinning. At higher strain rates (ε̇ ≥ 102 s−1) a transition to deformation twinning is observed, characterized by exhaustive {1122}〈1123〉 twinning and twin-twin interactions. This shift in deformation mode coincides with a notable increase in flow stress. In contrast, for compression perpendicular to the c – axis, plastic deformation is consistently accommodated by prismatic {1010}〈1120〉 slip across the entire range of strain rates, without showing any evidence of twinning or kink band formation. Additionally, the flow stress is significantly (7x) lower than that under c – axis loading. This work provides direct experimental evidence of strain rate-induced transitions in deformation mechanisms of α-Ti at the microscale