Uniaxial and Biaxial Mechanical Behavior of Nb ₄ C ₃ MXene Under Temperature, Strain Rate, and Vacancy Effects: A Molecular Dynamics Study

ABSTRACT 2D MXene have emerged as promising candidates for next‐generation structural and functional materials due to their exceptional mechanical, thermal, and electronic properties. In this study, the uniaxial and biaxial mechanical responses of Nb 4 C 3 MXene nanosheets were systematically investigated under varying temperatures, strain rates, and point vacancy concentrations using classical molecular dynamics simulations with the MEAM potential. The key mechanical properties, including Young's modulus, fracture strength, and fracture strain, were evaluated along both armchair and zigzag directions. The results reveal that increasing temperature significantly reduces the tensile strength, from 28.11 to 17.28 GPa in the armchair direction, from 32.64 to 19.16 GPa in the zigzag direction, resulting in a 41.29% reduction, and from 9.53 GPa to 7 GPa, corresponding to a 26.5% reduction under biaxial loading. Similarly, lower strain rates exhibited ductile‐like deformation, while higher strain rates enhanced strength but promoted brittle fracture. The introduction of vacancies, particularly random distributions, noticeably degraded the elastic modulus and fracture strain, with reductions of up to 21.8% depending on vacancy type and concentration. Fracture mechanism analysis indicated that pristine Nb 4 C 3 nanosheets failed via bond stretching and crack propagation, whereas vacancy‐induced defects accelerated crack initiation and reduced structural stability.