Grain rotation dependent fracture toughness of nanocrystalline materials

A grain size dependent theoretical model is developed to describe the effect of special rotational deformation (SRD) on crack growth in deformed nanocrystalline (nc) materials. The SRD is driven by the stress concentration near the crack tip, and it serves as a toughening mechanism by releases part of the local stresses. The dependence of critical crack intensity factors on grain size was calculated. It was demonstrated that the SRD leads to an increase of critical crack intensity factors by 10–50%.