First principles calculations of beryllium stability in zirconium surfaces

High-temperature oxidation of zircaloys poses a serious safety risk for nuclear fuel cladding applications, thus driving the search for oxidation resistant alloys. Ellingham diagrams suggest preferential oxidation of beryllium over zirconium, but the atomic-scale behavior of Be near Zr surfaces is unknown. We perform first principle calculations using density functional theory to investigate the stability of Be at possible sites in the Zr surfaces and bulk. Our calculations predict that Be favors substitutional sites and prefers to segregate to the surface layers. Charge density analysis shows charge redistribution around the solute atom in substitutional sites which leads to increased bonding and explains the high stability of these sites. The calculated surface segregation energy suggests that Be migrates towards the surface at high temperatures, which could enhance oxidation resistance.