Abstract:

To explore the fracture mechanism of metal nanowires,  a fracture process of Cu nanowire upon stretch was theoretically studied by molecular dynamic (MD) simulations based on embeddedatom method (EAM) potential. The relationship between stress, strain and dislocation before fracture as well as the morp
hology evolution after fracture was analyzed. The results demonstrate that the tips on the two ends of the nanowire can stuck the dislocation motion. Then the stacking fault by the first partial dislocation could be annihilated by a full dislocation formed by another partial dislocation. This process  can thus enhance the fracture strength. The sharp structure after fracture can retract and become obtuse spontaneously. The atomic scale analysis of the morphology change demonstrates that the fracture is a process of eliminating the high energy structures, such as isolated atoms, twin boundary and surface kink. The surface of the fracture finally emerge many (111) facets with lower energies. Therefore the physical mechanism is attributed to the rule of energy minimization.

Key words: Cu nanowire, material fracture, dislocation motion; micro-morphology