Cold welding assisted self-healing of fractured ultrathin Au nanowires

In nano-electronic field, cold welding is a simple novel method to join ultrathin noble metal nanowires (NWs) without introducing extra energy and defects. In previous works, it always occurred between ultrathin noble metal NWs, tensile fracture parts of a single NW, or a NW formation from nanoparticles. However, some external force is still needed to drive the materials as close to each other as possible before the process. Here, we proposed a new method to achieve cold welding without introducing artificial loadings. The bending fractured ultrathin gold (Au) NW can be self-healed assisted by cold welding during the removal of the tungsten (W) tip by in situ transmission electron microscope (TEM). A new interface with lattice mismatch formed in the welding zone after multiple periodic cycles, leaving an angle between the two rebonded fracture parts. Furthermore, the cold welding assisted self-healing of the bending fractured ultrathin Au NW and atom evolutions were also confirmed by molecular dynamics (MD) simulations. The successful implementation of cold welding makes the self-healing come true when the ultrathin Au NW fractures under the unexpected vibrations.