Impeding effect of cerium on the growth of helium bubble in iron

TL;DR

This study uses first-principles calculations to show that cerium atoms can trap helium in iron, reducing helium bubble growth by pinning helium atoms and creating energy barriers at bubble surfaces.

Contribution

It reveals that cerium's attraction to helium and its segregation at bubble surfaces can impede helium bubble growth in iron, a novel insight for material design.

Findings

Ce strongly attracts He in bcc Fe (-1.31 eV)

Ce can pin mobile He atoms, reducing cluster merging

Ce segregation creates an energy barrier of 0.33 eV to He atoms

Abstract

Our first-principles density functional theory calculations suggest that the rare earth element, Ce, has a stronger attraction (-1.31eV) to He than He-He (-1.18eV) in bcc Fe. Consequently, the mobile He atoms could be pinned to Ce, and hence a reduced merging of He clusters. Moreover, we find that the segregated Ce layer at the He bubble surface presents an energy barrier of 0.33 eV to the upcoming He atom and thus slows down the bubble growth.