The elemental effects on the H2 dissociative adsorption on FeCrAl (110) surface.

As a promising candidate for accident-tolerant fuel (ATF) cladding materials, FeCrAl alloys are susceptible to hydrogen embrittlement (HE) under high-temperature radioactive water environments. Understanding the HE mechanism of FeCrAl is crucial, and studying H 2 dissociative adsorption can provide valuable insights since it is the first step in the HE processes. In this paper, we investigated the H 2 dissociative adsorption on Fe (110) and FeCrAl (110) surfaces using first-principles calculations based on Density Functional Theory (DFT). Our results indicate that the decomposition of H 2 molecules on FeCrAl (110) surfaces is significantly affected by surface elemental effects compared to Fe (110) surfaces. Specifically, Al atoms weaken both the H 2 decomposition and the H binding strength of Al-containing sites. Cr atoms decrease the decomposition tendency of H 2 in certain configurations, but Cr aggregation enhances the binding strength of H atoms on Cr-containing sites. The mechanism underlying the Al/Cr weakening effects on H 2 decomposition is due to the charge deficiency through alloying. Our findings have generalized implications for studying the interactions between iron-based alloys and hydrogen in various applications such as hydrogen storage, transportation, and prevention. • The strength of H 2 –Fe/Cr/Al interactions follow the order: H 2 –Al < H 2 –Cr < H 2 –Fe. • Al atoms have strong weakening effect on H 2 dissociation compared to Fe. • Cr atoms have slight weakening effect on H 2 dissociation compared to Fe. • The Cr aggregation can enhance H 2 –Cr interaction & H binding strength. • The weakening effects of Al & Cr on H 2 dissociation are caused by the charge deficit of Al & Cr after alloying with Fe. [ABSTRACT FROM AUTHOR]