Figure 6
A schematic illustration shows the precursors of deformation twin are initiated at a near grain boundary region as a result of the impingement between piled-up dislocations and an annealing twin boundary. The stacking fault S.F.1 is formed by a cross-slip dislocation reaction. S.F.2 and S.F.3 are formed by a grain boundary stress relaxation reaction. The Burgers vector of incoming dislocations \({\text{b}}_{\text{in}}\) was designated to be \({\text{a}}/{2}{\text{[0}\bar{1}\text{1]}}_{\text{A}}\) or \({\text{a}}/{6}{\text{[}\bar{4}\bar{1}\text{1]}}_{\text{B}}\) after a proper matrix transformation, whereas the Burgers vectors of b1 \({\text{and}}\) b2 were assumed to be two Shockley partial dislocations (\({\text{a}}/{6}{\left[\bar{2}\bar{1}{\text{1}}\right]}_{\text{B}}\) and \({{\text{a}}/{6}\left[\bar{2}{\text{11}}\right]}_{\text{B}})\) that are emitted to minimize the magnitude of Burgers vector of grain boundary dislocations.
