Molecular Dynamics Simulation of Indentation Behavior Tests on Silicon Carbide

Silicon carbide (SiC) is widely used in high-temperature and high-hardness applications. Knowledge of its mechanical response is essential for understanding deformation mechanisms at the atomic scale. In this study, molecular dynamics simulations were performed to investigate the indentation behavior of three SiC polytypes (3C-, 4H-, and 6H-SiC). Indenter size and crystallographic orientation were varied to examine their influence on elastic and plastic deformation. At small indentation depths (5% - 10%), all polytypes exhibit primarily elastic behavior, with minor changes in energy, low root mean squared displacements (RMSD), stable pair correlation functions, and only minor changes in the frequency spectra. With increasing indentation, irreversible structural changes appear, including bond breaking, dislocation activity, and local amorphization. The hexagonal polytypes (4H- and 6H-SiC) show pronounced anisotropy, with direction-dependent energy evolution, RMSD, pair distribution functions and shifts of the high-frequency peaks in the vibration spectra. In particular, 6H-SiC exhibits non-monotonic RMSD behavior and splitting of coordination peaks at high indentation depths, indicating the formation of metastable atomic configurations and increased amorphization. These findings demonstrate that the mechanical response of SiC is governed by the interplay of elastic, plastic, and amorphization processes, and that lattice anisotropy plays a key role in determining the deformation pathways.