Atomic-scale interface structure of a Cr-coated Zircaloy-4 material

Highly adherent, thin Cr coatings on Zr-based nuclear fuel claddings can be potentially used for the development of accident-tolerant fuels in light water reactors. To guarantee the successful implementation of Cr-coated Zr alloys as cladding tubes in nuclear power plants, the adhesive strength of the Cr coatings must be assessed. The interface between Cr and Zr was characterized via high-resolution transmission electron microscopy. We observed the formation of nanometer-thick Zr(Fe, Cr)2 poly-type, structured Laves phases at the interfacial region that display both C14 and C15 lattice symmetries. Although the crystallinity was preserved throughout the interfacial region, different atomic configurations were observed for all the interfaces studied. In most cases, coherent or semicoherent crystallographic relationships were observed, ensuring the adhesive strength of the coating.