Molecular dynamics study of the interface fine structure and mechanical properties of Ni@SWCNT/Cu nanocrystalline composite materials

The use of carbon nanotubes (CNTs) as reinforcing phase in copper-based composites has been extensively studied. However, controlling the synthesis interface structure and explaining the nanoscale interface bonding mechanism through experimental methods still poses challenges. In this study, a model of single-walled carbon nanotube nanocrystalline copper composite was established based on molecular dynamics (MD) simulations to investigate the effects of grain boundaries and dislocations on the composite material. It was found that the addition of nickel atoms improved the interface bonding between carbon nanotubes and the copper matrix, reducing vacancies at the interface. Ni@SWCNT/Cu exhibited better mechanical properties. Structural changes and defect evolution during deformation were studied. The ultimate tensile strength of SWCNT/Cu and Ni@SWCNT/Cu composites increased by 62.29% and 68.78% respectively compared to nanocrystalline copper, while the Young's modulus increased by 25.91% and 32.48% respectively; moreover, the Young's modulus of these two composites increased by 45.24% and 49.42% respectively. Ni@SWCNT/Cu had the lowest wear rate and friction coefficient, with a minimum wear rate of 0.0055 and a minimum friction coefficient of 0.67, demonstrating better wear resistance. The effects of different friction speeds and depths of indentation on the friction performance of the composite materials were also investigated.