Damping effect of (110)<001> symmetric tilt grain boundaries on the shock response of SiC

Abstract

The effect of grain boundaries on the impact response of SiC remains insufficiently investigated. In this research, molecular dynamics simulations were utilized to examine the impact response and deformation mechanisms of SiC featuring symmetric tilt grain boundary (STGB) structures at an impact velocity of 2 km/s. Four different tilt angles of 4.24°, 8.7°,16.26°, and 36.9° are considered and compared with the corresponding single-crystal. The results reveal that the presence of STGB significantly alters the response mechanisms in SiC, with these mechanisms changing based on the tilt angles. Specifically, when the tilt angle is <16.26°, GBs promote plastic deformation at the boundary as the shock wave passes through, which extends into the adjacent grains, forming two-sided GB plasticity. Simultaneously, a substantial attenuation of wave amplitude occurs, generating an impact damping effect. However, when the tilt angle exceeds 16.26°, one-sided GB plasticity is observed, the SiC structure becomes unstable, and the damping effect disappears. All the results indicate that the damping effect reaches its optimal effect at 16.26°. These findings offer valuable insights into impact protection under extreme conditions and may inspire novel approaches for designing nano-ceramic materials with enhanced protective properties.