Dislocation dissociation induces secondary twinning in titanium

The twin–twin interaction phenomenon in Ti is studied by incorporating experimental observation and theoretical analysis. Secondary {101̅2} twins are stimulated in primary {112̅2} and {112̅4} via twinning dislocation dissociation. Primary twin variants are found either share the same ⟨101̅0⟩ zone axis or with different zone axes. Schmid law, dislocation theory and crystallographic analysis are used to investigate the formation processes and physical mechanisms of the twin–twin interaction phenomenon. Results show that non-Schmid secondary twins are stimulated under the effect of primary twinning interactions. Besides to secondary twinning dislocations, glissile and sessile dislocations generate as a result of primary dislocation dissociation. Glissile dislocation glide on the easy slip prismatic plane, while sessile dislocation accumulates and leads to the increase of local strain.