Crack nucleation due to dislocation pile-ups at twin boundary-grain boundary intersections

According to the mechanism of wedge crack nucleation at twin boundary-grain boundary intersections, a corresponding model was built to analyze the nucleation of crack quantitatively. The results showed that crack nucleation was easier for a higher applied stress or an increasing twin lamellae thickness. For different boundary orientation, the resolved shear stress on boundary was different, which led to the variations of the energy of pile-up dislocations and the energy of crack nucleation. Thus, boundary orientation also had a significant influence on crack nucleation. Moreover, decreasing grain size resulted in a smaller critical twin lamellae thickness for crack nucleation.