Crystallization behaviors and mechanical properties of carbon nanotube encapsulated copper nanowires

Abstract

Based on the molecular dynamics (MD) simulation, the crystallization behaviors and tensile mechanical properties of carbon nanotube (CNT) encapsulated copper nanowires are investigated in this paper. The influences of the cooling rate, the wall number of CNT and the cross-sectional diameter are considered. It is found that during the crystallization process the CNT acts as a template to induce the nucleation of copper grains from the surface and the template effect is mainly dominated by the innermost layer of CNT via the van der Waals interaction. CNT encapsulated copper nanowire can be formed after the cooling process and the internal copper nanowire is composed of several circumferential fan-shaped polycrystalline grains separated mostly by radial grain boundaries. The crystallinity increases with the increase of the diameter and the decrease of the cooling rate. Tensile tests show that the strength of the composite structure of the CNT encapsulated copper nanowire is much larger than the corresponding pristine copper nanowire. Moreover, it is found that the strength of the composite structure increases with the decrease of the diameter and the CNT plays a dominant role in strengthening the materials. These findings will shed light on the fabrication and practical application of carbon nanotube encapsulated metal nanowires.