Influence of Crystallographic Orientation on Twin Nucleation in Single Crystal Magnesium

CD Barrett and MA Tschopp and H El Kadiri and B Li, MAGNESIUM TECHNOLOGY 2011, 295-299 (2011).

Experimental plasticity on single crystals has found substantial non- Schmid effects in both twinning and non-basal slip in pure magnesium. The deviation from Schmid's law has been attributed to the strong sensitivity of both twinning and slip to small lattice heterogeneities 1 and the effect of pre-slip and non-planar dislocation dissociation 2. However, most molecular dynamics simulations use heterogeneities so the effect of slip on twin nucleation and vice-versa has been shrouded. This has motivated us to investigate the influence of crystal loading orientation on homogeneous slip and twin nucleation using molecular dynamics. These simulations allowed us to appreciate the propensity and nature of twin nucleation when pre-existing defects are absent. Analyses of deformation mechanisms and stress-strain responses shows that homogeneous dislocation nucleation on the basal slip system is correlated with the highest Schmid resolved shear stress, while homogeneous nucleation of tensile twins did not always correlate with the highest Schmid resolved shear stress.

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