Grain size effect on deformation twinning propensity in ultrafine-grained hexagonal close-packed titanium

The deformation behaviour of ultrafine-grained hexagonal close-packed Ti processed by dynamic plastic deformation was investigated using electron microscopy techniques. Results show that the deformation twinning propensity in ultrafine-grained Ti decreases monotonously while the number of dislocations having the 〈c〉 component increases with decreasing grain size, indicating that the transformation of the deformation mechanism from twinning to slip occurs and that the twinning mechanism does not change within the observed grain size range.