Application of a continuum dislocation-based model to a tensile test on a thin film

Plastic deformation on the microscale shows a significant size effect in the sense that plastic response is stronger than that of macroscopic bulk materials. This effect is often ascribed to the deposition of misfit dislocations, to the presence of geometrically necessary dislocations or to bowing-out of discrete dislocations. The models based upon these assumptions do predict the size effect, but they are not completely satisfactory. This paper discusses an alternative model, based upon the continuum-theory of dislocations, which ascribes size effects to the bowing of continuously distributed dislocations, treated within a rigorous continuum mechanics framework. Results are compared to those of tensile tests on thin Cu-films, presented in the literature. A quantitative agreement is found concerning the size effect and the influence of grain orientation.