Collision cascades overlapping effect with cavity/Xe bubble in 3C-SiC:Atomistic simulations and experimental investigations

Abstract

Heavy gaseous fission product bubbles in nuclear fuel pose a significant influence on the microstructure and properties of coating materials. We employ atomistic simulations, successive carbon and xenon (Xe) ion irradiation experiments, and TEM observations to explore the effects of Xe bubbles and cascade overlap on 3C-SiC, with a particular focus on the Xe/V ratio, bubble size, shape, and stability. Our findings reveal that under a fixed Xe/V ratio, bubbles attract vacancies, leading to increased bubble size. When the bubble diameter is held constant, Xe atoms continue to accumulate until reaching a critical Xe/V value of 0.8, at which point recoil bursting occurs. Cascade overlap transforms the linear cascade behavior of SiC into a surface distribution that dissolves around bubbles. Xe bubbles with high crystallinity (Xe/V = 0.7) repeatedly undergo amorphization and recrystallization during cascade overlap, inhibiting the thermal recovery of self-interstitial atoms in SiC after thermal spikes and enhancing C-C homonuclear bonding around the bubbles. Moreover, we demonstrate that at Xe/V values exceeding 0.5, bubble pressure induces plastic deformation, forming interstitials and promoting chemical disorder and amorphization in the SiC matrix during growth and irradiation. These findings provide fresh insights into the behavior of heavy-atom bubbles under complex irradiation conditions in the SiC matrix.