A coupling crack blunting mechanism in nanocrystalline materials by nano-grain rotation and shear-coupled migration of grain boundaries

Strong Crack Blunting by Hierarchical Nanotwins in Ultrafine/Nano-grained Metals

“…By modifying the standard mode I brittle crack growth criterion, [35][36][37][38] which was established based on the balance between the driving force related to a decrease in elastic energy and the hampering force due to the creation of a new free surface during crack growth, an effective critical stress intensity factor K e IC is developed to account for the coupling effect of detwinning of the secondary twins and the slip of the dislocations emitted from the crack tip on crack growth. In this case, the propagation of crack is assumed to occur solely under the action of the tensile load perpendicular to the crack growth direction, while the presence of the disclinations and dislocations simply cause a change to the K e IC value.…”