Atomistic simulations had shown that a screw dislocation in body-centered cubic metals had a complex non-planar atomic core structure. The configuration of this core controlled their motion and was affected not only by the usual resolved shear stress on the dislocation, but also by non-driving stress components. Consequences of the latter were referred to as non-Schmid effects. These atomic and micro-scale effects were the reason slip characteristics in deforming single and polycrystalline body-centered cubic metals were extremely sensitive to the direction and sense of the applied load. A three-dimensional discrete dislocation dynamics simulation model was developed here in order to understand the relationship between individual dislocation glide behaviour and macro-scale plastic slip behaviour in single crystal body-centered cubic Ta. For the first time, it was shown that non-Schmid effects on screw dislocations of both {110} and {112} slip systems had to be implemented in the dislocation dynamics models in order to predict the strong plastic anisotropy and tension–compression asymmetry experimentally observed in the stress–strain curves of single-crystal Ta. Incorporation of fundamental atomistic information was critical for developing a physics-based, predictive meso-scale dislocation dynamics simulation tool that could connect length/time scales and investigate the underlying mechanisms governing the deformation of body-centered cubic metals.

An Atomistically-Informed Dislocation Dynamics Model for the Plastic Anisotropy and Tension–Compression Asymmetry of BCC Metals. Z.Q.Wang, I.J.Beyerlein: International Journal of Plasticity, 2011, 27[10], 1471-84