  The competition between deformation twinning and dislocation slip underpins
the evolution of mesoscale plasticity in face-centered cubic materials. While
competition between these mechanisms is known to be related to the critical
features of the generalized planar fault energy landscape, a physical theory
that tracks competition over extended plasticity has yet to emerge. Here, we
report a methodology to predict the mesoscale evolution of this competition in
deformed crystals. Our approach implements kinetic Monte Carlo simulations to
examine fault structure evolution in face-centered cubic metals using intrinsic
material parameters as inputs. These results are leveraged to derive an
analytical model for the evolution of the fault fraction, fault densities, and
partitioning of plastic strains among deformation mechanisms. In addition, we
define a competition parameter that measures the tendencies for deformation
twinning and dislocation slip. In contrast to previous twinnability parameters,
our derivation considers deformation history when examining mechanism
competition. This contribution therefore extends the reach of deformation
twinning theory beyond incipient nucleation events. These products find direct
applications in work hardening and crystal plasticity models, which have
previously relied on phenomenological relations to predict the mesoscale
evolution of deformation twin microstructures.
