Evolution of microstructural deformation mechanisms under equal-channel angular extrusion loading conditions: a molecular dynamics case study of single crystal titanium

Classical molecular dynamics simulations have been performed to investigate the microstructural evolution of single crystal titanium under equal channel angular extrusion process (ECAE). The ECAE loading condition has been simulated by constraining deformation along two directions and applying shear along one direction. We find that for the case where shear is applied along <21¯1¯0> direction, the material yields at higher value of stress in comparison to the case where shear is applied along <011¯0> direction. The {101¯1} and {101¯2} twins activate for the case where shear is applied along <21¯1¯0> direction and the deformation is primarily accommodated by twinning, dislocation slip and structural phase transformation. The ω-phase volume fraction increases, reaches a peak and then decreases. The decrease in ω-phase volume fraction indicates that the ω-phase is not stable. For the case where shear is applied along <011¯0> direction, no twinning occurs and the deformation is primarily accommodated by the dislocation slip.