Evolution of dislocation loops in chromium under single hydrogen and helium ion irradiation

Dislocation loops, which are typical irradiation defects, can be influenced by hydrogen and helium produced by transmutation reactions. The evolution of dislocation loops in chromium (Cr) coatings under room temperature irradiation with single H⁺ and He⁺ is observed using transmission electron microscopy (TEM). At equivalent damage levels, the density of dislocation loops is higher under irradiation with He⁺ compared to that with H⁺. This indicates that helium promotes the nucleation of dislocation loops more effectively than hydrogen does, whereas hydrogen promotes the growth of dislocation loops more, resulting in larger loop sizes. Irradiation with both hydrogen and helium ions resulted in the formation of more a₀ 〈100〉 dislocation loops in Cr, comprising roughly half of the total observed loops.