Controlling Plastic Flow across Grain Boundaries in a Continuum Model

A framework for modeling controlled plastic flow through grain boundaries using a continuum plasticity theory, phenomenological mesoscopic field dislocation mechanics (PMFDM), is presented in this article. The developed tool is used to analyze the effect of different classes of constraints to plastic flow through grain boundaries, as it relates to dislocation microstructure development and mechanical response of a bicrystal. It is found that in the case of low misorientation angle between adjacent grains, impenetrable grain boundaries cause significant work hardening as compared to penetrable grain boundaries due to the accumulation of excess dislocations along them. However, a penetrable grain boundary with a high misorientation angle effectively behaves as an impenetrable boundary, with respect to the stress-strain response.