Bulk submicrocrystalline ω-Ti produced by high-pressure torsion straining

Pure Ti consisting of 90 mass% ω-phase with a grain size of a few hundred nanometers and a Vickers microhardness of Hv 3.7 GPa is produced by high-pressure torsion straining under 5 GPa with an equivalent strain of >100 at 0.2 rpm at room temperature. The stabilization of ω-phase at ambient condition occurs via the application of shear deformation in the ω-phase state, and the fraction of ω-phase increases with strain. The metastable ω-phase reverse-transforms to α-phase at 150 °C.