Effect of H and Pd atoms on the migration of He atoms in 3C–SiC

Abstract

3C–SiC is an important structural material for tri-structural isotropic coated fuel particles in high-temperature gas reactors. It serves as a vital pressure vessel for gas fission products and a shielding layer for metal fission products. However, the accumulation of interstitial He atoms can lead to the formation of He bubbles, which threaten the safe service of materials. A study of how interstitial atoms affect the migration of He atoms can help us understand the nucleation of He bubbles in SiC cladding materials. The effects of H and Pd interstitials on the solution energy and migration behavior of He atoms were investigated. It was found that H favored He atoms to approach it, while Pd has the opposite effect, causing He atoms to move away from it. Under the synergistic effect of H and Pd atoms, He atoms tend to move away from the Pd interstitial, similar to the effect of the Pd interstitial alone. Furthermore, the external H interstitial strengthens the effect of Pd atoms on He atoms, drastically reducing the migration energy of He atoms away from Pd.