Plastic deformation of multicrystalline thin films: Grain size distribution vs. grain orientation

A continuum model of plasticity, Mesoscopic Field Dislocation Mechanics (MFDM), is used to study the interplay between grain size and grain orientation on the mechanical response of multicrystalline thin films undergoing plane strain tension. It is shown that the grain size dependence in the case of multicrystals is controlled by those grains which are relatively more susceptible to plastic deformation. This effect is captured to some extent by conventional crystal plasticity theory; however, the explicit incorporation of polar dislocations in the MFDM model significantly enhances the overall mechanical response as demonstrated in the paper.