  Dislocation motion in body centered cubic (bcc) metals displays a number of
specific features that result in a strong temperature dependence of the flow
stress, and in shear deformation asymmetries relative to the loading direction
as well as crystal orientation. Here we develop a generalized dislocation
mobility law in bcc metals, and demonstrate its use in discrete Dislocation
Dynamics (DD) simulations of plastic flow in tungsten (W) micro pillars. We
present the theoretical background for dislocation mobility as a motivating
basis for the developed law. Analytical theory, molecular dynamics (MD)
simulations, and experimental data are used to construct a general
phenomenological description. The usefulness of the mobility law is
demonstrated through its application to modeling the plastic deformation of W
micro pillars. The model is consistent with experimental observations of
temperature and orientation dependence of the flow stress and the corresponding
dislocation microstructure.
