Investigating the mechanical properties and deformation behavior of Ni/SiC nanocomposites using molecular dynamics simulations

Ni/SiC ceramic metal-based nanocomposites exhibits outstanding mechanical properties and radiation resistance, making it a promising candidate for essential structural materials in molten salt reactors. This study utilized molecular dynamics simulation to investigate the influence of uniaxial tensile rate and volume fraction (VF) of SiC on the tensile mechanical properties of Ni/SiC nanocomposites, as well as to reveal the deformation mechanism during uniaxial tensile. The results demonstrate a semi-logarithmic relationship between the Young’s modulus and strain rate of Ni/SiC composites, with the yield strength being correlated to the tensile rate. When the tensile rate was less than 1×10⁹/s, the yield strength remained essentially unchanged. However, when the tensile rate exceeded this threshold, the yield strength increased with the increase in tensile rate. Additionally, the VF of SiC significantly influenced the tensile mechanical properties of Ni/SiC nanocomposites, with critical volume fraction (CVF) of SiC calculated to be 0.299±0.04. When VF of SiC was below the CVF, the uniaxial tensile properties of Ni/SiC nanocomposites were mainly determined by the properties of the Ni matrix, and strain hardening was not observed. The deformation mechanism was attributed to the release a large number of dislocations at the Ni-Ni interface, demonstrating excellent plasticity. Conversely, when the VF of SiC exceeds the critical value, the mechanical behavior of Ni/SiC nanocomposites was primarily affected by SiC, leading to increased strain hardening and brittleness. The initial cracks formed at the Ni-Ni interface and propagated with increasing strain, with the slip of the Ni-Ni interface and the rotation of SiC grains are identified as the main reasons for the plastic deformation of Ni/SiC. These findings contribute to a better understanding of the mechanical properties of Ni/SiC composites and their potential applications, offering valuable guidance for the selection of structural materials for molten salt reactors.