On radiation-free velocities of edge dislocations in arbitrary slip systems of anisotropic crystals

Transonic defect motion is of interest for high strain-rate plastic deformation as well as for crack propagation. Ever since Eshelby's 1949 prediction in the isotropic limit of a 'radiation-free' transonic velocity $v_\text{RF}=\sqrt{2}c_{\textrm{T}}$, where shock waves are absent, there has been speculation about the significance of radiation-free velocities for defect mobility. Here, we argue that they do not play any significant role in dislocation dynamics in metals, based on comparing theoretical predictions of radiation-free velocities for transonic edge dislocations with molecular dynamics simulations for two face-centered cubic (FCC) metals: Cu, which has no radiation-free states, and Ag, which does.