A theoretical model for studying the mechanical properties of bimodal nanocrystalline materials

A new theoretical model is proposed to describe the mechanical properties of bimodal nanocrystalline (BNC) materials. This composite model is comprised of coarse grains evenly distributed in the nanocrystalline (NC) matrix. In this study, we have studied the effect of grain size distribution on the constitutive behavior of BNC materials. During the plastic deformation, effects of nanocracks and dislocation emission from crack tips on the constitutive behavior of BNC materials are also analyzed. Numerical calculations have been carried out according to the model, and it is found that the nanocracks make a positive effect on the strain hardening, and the results show that this model can describe the enhanced strength and strain hardening of BNC materials successfully. The prediction of the bimodal Cu-Ag material is in good agreement with the experimental results.