Strength and strain hardening of nanocrystalline materials

In this paper, a phase mixture model was employed to simulate the strain hardening properties of metallic materials covering a wide grain size range from micrometer down to nanometer scale. In this model a polycrystalline nanomaterial is treated as a mixture of two phases: grain interior, whose plastic deformation is governed by a combination of the dislocation and diffusion mechanisms, and grain boundary ‘phase’, whose plastic flow is controlled by a boundary diffusion mechanism alone. The main focus of the paper is the effect of grain size on the flow stress and strain hardening. The model predictions of the grain size dependence of strain hardening are presented.