Theoretical models are reviewed which describe misfit defect structures at
interfaces (intergrain and interphase boundaries) in nanostructured
and polycrystalline films. The specific structural and behavioral
features of interfaces in nanostructured and polycrystalline films
are discussed which influence the macroscopic properties of such films.
The special attention is paid to theoretical models describing partial
misfit dislocation structures, misfit disclinations,
misfit dislocation walls, grain boundary dislocations as misfit defects and
partly incoherent interphase boundaries
in nanostructured and polycrystalline films.
Also, the effects of misfit strains on phase transformations
in multilayer composites as well as the behavior of nano-islands
on composite substrates are considered.