Plastic deformation mechanisms of nanotwinned Mg with different twin boundary orientations: molecular dynamics simulations

Abstract

ABSTRACT Molecular dynamics (MD) are employed to study the plastic deformation mechanisms of nanotwinned (NT) Mg with different twin boundary (TB) orientations under uniaxial tension. The orientation effect on the plastic deformation mechanisms of NT Mg is discussed. When the uniaxial tension is applied perpendicular to the TB plane, the emission of basal partial dislocations (BPDs) dominates the plastic deformation. The BPD-TB interaction and the gradual loss of coherence of TBs contribute to the ductility of NT Mg. With the increasing of the TB orientation angle (α), the twining dislocations (TDs) nucleate at the TB due to the shear component on the TB plane, the basal-dislocation-governed deformation transfers to the twinning-dislocation-governed deformation. The gliding of TDs along the TBs causes the migration of TBs and the subsequent detwinning. An obvious strain hardening is observed after the detwinning due to the disappearance of TBs.