Mechanisms during Strain Rate-Dependent Crack Propagation of Copper Nanowires Containing Edge Cracks

The crack propagation mechanism of Cu nanowires is investigated by using molecular dynamics methods. The microstructural evolution of crack propagation at different strain rates and crack depths is analyzed. Meanwhile, the stress intensity factor at the crack tip during crack propagation is calculated to describe the crack propagation process of Cu nanowires under each condition. The simulation results show that the competition between lattice recovery and dislocation multiplication determines the crack propagation mode. Lattice recovery dominates the plastic deformation of Cu nanowires at low strain rates, and the crack propagation mode is shear fracture. With the increase in strain rate, the plastic deformation mechanism gradually changes from lattice recovery to dislocation multiplication, which makes the crack propagation change from shear fracture to ductile fracture. Interestingly, the crack propagation mechanism varies with crack depth. The deeper the preset crack of Cu nanowires, the weaker the deformation resistance, and the more likely the crack propagation is accompanied.

Automated summary

The crack propagation mechanism of Cu nanowires was investigated using molecular dynamics methods. The microstructural evolution of crack propagation was analyzed at different strain rates and crack depths. The competition between lattice recovery and dislocation multiplication was found to determine the crack propagation mode. Lattice recovery dominated the plastic deformation at low strain rates, resulting in shear fracture. With increasing strain rate, the plastic deformation mechanism shifted to dislocation multiplication, leading to ductile fracture. Interestingly, the crack propagation mechanism also varied with crack depth, with deeper cracks having weaker deformation resistance and a higher likelihood of crack propagation.