Dislocation motion in phonon liquids

The motion of dislocations through a phonon liquid can be expected to shed vortices because the estimated Reynolds number is in the appropriate range. The stresses produced by vortex shedding are ample to cause cross-gliding of screw dislocations and thereby deformation hardening. As the phonon number density decreases with decreasing temperature, the Reynolds number is expected to increase, and therefore the deformation-hardening rate increases. This may account for the rise in the flow stresses of body-centered cubic metals at low temperatures.