Interface-Driven Strengthening and Defect Mitigation in Nickel Nanowires via Carbon Nanotube Coatings

Nickel nanowires (NiNWs) are promising structural and functional components for nanoscale technologies, including nanoelectromechanical systems, nanoelectronics, sensing, and catalysis. Their mechanical performance and reliability, however, are strongly affected by crystallographic orientation and structural defects, particularly at dimensions where surface and interface effects become dominant. Void defects act as stress concentrators and preferential sites for dislocation nucleation and damage localization, thereby reducing the mechanical integrity of NiNWs. Although carbon nanotubes (CNTs) possess exceptional mechanical properties, their ability to mitigate defect-induced weakening in metallic nanowires and the influence of CNT architecture, defect location, and crystallographic orientation remain insufficiently understood. 

In this study, large-scale molecular dynamics simulations are employed to investigate the tensile behaviour and deformation mechanisms of pristine andCNT-coated NiNWs containing surface and internal void defects. Two crystallographic orientations, <111> and <001>, are considered to examine orientation-dependent deformation mechanisms. The reinforcing effects of single-walled and double-walled carbon nanotube coatings (SWCNTs and DWCNTs) are compared to evaluate the influence of CNT architecture on strengthening and defect tolerance.

The results reveal a pronounced crystallographic dependence of the mechanical response. Pristine <111> oriented NiNWs exhibit higher stiffness and tensile strength than <001> oriented counterparts, reflecting differences in atomic packing and dislocation-mediated deformation. Void-induced degradation is also orientation dependent: surface voids are particularly detrimental to <111> oriented nanowires, whereas internal voids cause a stronger reduction in the mechanical performance of <001> oriented systems. The evolution of dislocation density and void surface area further demonstrates that defect location significantly influences the initiation and progression of plastic deformation.

CNT coatings substantially modify the deformation response by enhancing load transfer and mechanically constraining theNiNW surface. Among the investigated configurations, DWCNT coatings provide the most effective reinforcement, significantly improving yield strength and ultimate tensile strength, with the latter increasing by up to511% in the most favourable configuration. The results demonstrate that the CNT–NiNW interface plays a central role in suppressing defect-induced deformation and improving defect tolerance.

This study identifies CNT architecture, crystallographic orientation, and defect location as coupled parameters governing the mechanical reliability of NiNWs and provides insights for designing defect-tolerant metallic nanowires for nanoscale mechanical and multifunctional applications.