Effect of Non-Glide Components of the Stress Tensor on Deformation Behavior of Bcc Transition Metals

Abstract

AbstractIn this paper we demonstrate by atomic computer simulation that the non-Schmid slip behavior in bcc metals is a direct consequence of the non-planar core structure of 1/2<111> screw dislocations and their response to the applied stress tensor. The analysis has been carried out in detail for tantalum using the Finnis-Sinclair type central force many-body potentials. Two distinct non-Schmid effects have been discerned. The first is twinning-antitwinning slip asymmetry on {112} planes. This is an intrinsic property of the bcc structure and depends on the sense of the applied glide stress. The second non-Schmid effect is extrinsic and is controlled by the non-glide shear stresses perpendicular to the total Burgers vector on {110} planes into which the stress-free core of screw dislocations spread.