MOLECULAR DYNAMICS MODELING OF THE EFFECT OF VACANCY CONCENTRATION ON THE MECHANICAL PROPERTIES OF CNT-REINFORCED α-TI UNDER UNIAXIAL TENSION

10.25712/ASTU.1811-1416.2025.04.007

Abstract

The aim of this study was to conduct a comparative analysis of the influence of point defect (vacancy) concentration and carbon nanotube (CNT) reinforcement on the deformation behavior and mechanical properties of a titanium single crystal under uniaxial tension. The study was performed using the molecular dynamics method in the LAMMPS software package. For all models, uniaxial stretching was performed with a constant strain rate at a temperature of 300 K. Key mechanical characteristics were determined: tensile strength, yield strength, and Young's modulus. A non-monotonic effect of vacancies on the strength of α-Ti has been established. It has been shown that a vacancy concentration of 0.5% leads to dispersion strengthening of the matrix (ultimate strength = 14.75 GPa, for a defect-free crystal = 14.43 GPa). The introduction of CNTs stabilizes the ultimate strength at a level of ~12 GPa for all vacancy concentrations, leveling their influence. It was found that the Young's modulus of the composite increases with an increase in the proportion of vacancies (up to 103.13 GPa at 1.0%), which indicates the dominant role of CNTs in elastic deformation. It was found that the composite destruction occurs by the mechanism of interphase delamination at the interface, which leads to a decrease in the yield strength. For models with embedded CNT, the key factor determining the mechanical properties of the composite is the strength of the matrix-CNT interface.