  Interface migration in microstructures is mediated by the motion of line
defects with step and dislocation character, i.e., disconnections. We propose a
continuum model for arbitrarily-curved grain boundaries or heterophase
interfaces accounting for disconnections' role in grain rotation. Numerical
simulations show that their densities evolve as grain size and shape change,
generating stresses and increasing or decreasing misorientation; the
predictions agree with molecular dynamics simulations for pure
capillarity-driven evolution, and are interpreted through an extended
Cahn-Taylor model.
