Abstract
The boundary structure of {1011} deformation twins formed in commercial pure titanium (CP-Ti) during the initial pass ECAP processing has been studied by TEM and HRTEM. A new twining mode with twinning dislocation of b3/3, has been identified by a dichromatic diagram method. The new mode of {1011} twin has substantially higher interface energy and accommodates more shear strain during deformation than the conventional b4 twinning mode. The deviation angle between the habit trace of the twin boundary and the theoretical twinning plane, K1, is dependent upon the density of twin dislocations.