  Dynamic recrystallization (DRX) is often observed in conjunction with
adiabatic shear banding (ASB) in polycrystalline materials. The recrystallized
nanograins in the shear band have few dislocations compared to the material
outside of the shear band. In this paper, we reformulate the recently-developed
Langer-Bouchbinder-Lookman (LBL) continuum theory of polycrystalline plasticity
and include the creation of grain boundaries. While the shear-banding
instability emerges because thermal heating is faster than heat dissipation,
recrystallization is interpreted as an entropic effect arising from the
competition between dislocation creation and grain boundary formation. We show
that our theory closely matches recent results in sheared ultrafine-grained
titanium. The theory thus provides a thermodynamically consistent way to
systematically describe the formation of shear bands and recrystallized grains
therein.
