Atomic-scale insights into diameter- and defect-dependent strengthening mechanisms of CuNi@CNT nanocomposites

Abstract

Carbon nanotube (CNT)–reinforced copper–nickel (CuNi) alloy matrix nanocomposites offer significant potential for advanced structural and multifunctional applications

however, the atomistic mechanisms by which CNT diameter and controlled vacancy defects govern load transfer, strengthening behaviour, and tensile failure evolution remain unclear. In this study, large-scale molecular dynamics simulations are performed to systematically investigate the tensile deformation behaviour of CuNi alloy matrix reinforced with pristine and 0.2% vacancy-defective single-walled CNTs of varying armchair chiralities [(5,5), (10,10), (15,15), and (20,20)] at 300 K. CNT reinforcement leads to pronounced enhancements in elastic modulus, yield strength, and ultimate tensile strength, with strength improvements exceeding 200% and failure strain increasing by more than 360% compared to the unreinforced CuNi alloy matrix. Higher-diameter armchair CNTs provide superior load transfer, delayed strain localisation, and enhanced deformation stability. Atomic strain analysis and dislocation extraction reveal that CNTs suppress shear band formation, dislocations, and promote homogeneous plastic flow. Introducing controlled vacancy defects maintains nearly the same peak strength and slightly reduces the maximum strain by 8%. These results provide new atomistic insight into diameter- and defect-dependent deformation mechanisms in CNT reinforced CuNi alloy matrix nanocomposites, clarifying structure–property relationships for high-strength, high-ductility composites. © 2026 Informa UK Limited, trading as Taylor & Francis Group.