Grain boundary effects on defect production and damage cascade evolution in SiC/PyC interface: A molecular dynamics study

In this study, molecular dynamics simulations were employed to investigate the effect of symmetrical tilt grain boundaries (STGBs) on the cascade collision evolution at the SiC/PyC interface. We observed that the tilt angle size of grain boundary (GB) spatial structures significantly influences both the type and number of defects caused by primary knock-on atom (PKA) collisions at the interface, altering the cascade damage morphology. Under the PKA range from 1.5keV to 15keV at 1000K, the interplay between GB and interface damage throughout various cascade collision stages impacts defect generation and PKA efficiency. Integrating the analyses of displacement cascade morphology, threshold displacement energy (TDE), and Frenkel pairs (FPs) evolution, it is evident that GBs introduced into the SiC/PyC interface with single crystals exhibit reduced defect absorption efficiency. This implies the existence of competing mechanisms of GB damage and interfacial damage. Notably, the GB plane near the interface exhibits enhanced irradiation resistance and atomic arrangement stability compared to areas without GB. Overall, our results offer crucial insights into the irradiation resistance mechanics of ceramic composite interfaces, laying the groundwork for future studies.