Non-Schmid behavior of extended dislocations in computer simulations of magnesium

Abstract

Critical resolved shear stresses are studied by means of atomistic simulations for dissociated screw dislocation with Burgers vector 1/3[112¯0] in magnesium. Deviation from Schmid law is demonstrated for dislocation glide on basal and prismatic planes. It was shown that all stress components have influence on the critical resolved shear stress. The non-Schmid behavior is caused by changes of dislocation core width due to acting of non-glide stress components. In atomistic simulations, the critical resolved shear stress varies in the range of 0.2–6.7 MPa for basal slip and 25–55 MPa for prismatic slip depending on values of non-glide stress components. It is expected that such behavior can be partially responsible for scattering of experimental data for yield stress in magnesium.