Strength scaling law, deformation kinetics and mechanisms of nanostructured Ti

We investigate the tensile properties, strain rate sensitivity, and activation volume of nanostructured Ti prepared by equal channel angular pressing plus a series of thermal treatment. Simultaneous enhancement of strength and tensile ductility is achieved. The strain rate sensitivity is found to decrease with decreasing grain sizes (~150-450. nm). A new Hall-petch relationship is presented and discussed. The analyses on the internal friction peaks at around -70 °C suggest that twins could play the primary role for the strain hardening of the annealed nanostructured Ti, consistent with the miniscule activation volumes.