Investigation of fracture behaviors in copper influenced by the angle of oblique edge nanocrack

Edge nanocracks originating from copper surfaces may cause the breakdown of small-scale electronics. It is important to understand the fracture mechanism of copper with edge nanocracks because these cracks can play a significant role in degrading the reliability of electronic devices. In this work, the effect of the oblique edge crack angle on the fracture behavior of copper with nanocracks was investigated. Edge crack models with three crack lengths and various crack angles were considered in the crack propagation simulations of copper using molecular dynamics. The simulations revealed that the fracture behavior of copper with edge cracks showed a transition from brittle to ductile behavior as the angle of the edge crack decreased, independent of crack length. The edge crack models with large crack angles showed crack propagation, whereas the models with small crack angles displayed dislocation emission and arrested crack propagation. The fracture behaviors at the crack tip were characterized by the energy release rate. The finite element method was used to calculate normalized stress intensity factors, which were a function of crack angle and showed no dependence on crack length. It was found that the oblique edge crack angle of the nanocracks in copper affects the fracture behavior, as it determines the mode mixity. The brittle fracture initiated from the nanocracks in copper was evaluated based on the mixed-mode fracture criterion, and the dislocation emission at the crack tip was discussed as an inhibiting mechanism of crack propagation.