Multicomponent guided surface oxide evolution and protection mechanisms for Zr-based high-entropy amorphous coatings under dual-environment conditions

The development of advanced coatings is vital for enhancing the accident tolerance of Zr alloy fuel claddings. This work systematically investigates the variations in oxidation and corrosion resistance from pure Zr to a magnetron-sputtered Zr-Nb-Fe-Cr-Si-Al high-entropy amorphous coating. The synergistic effect of multi-element alloying, particularly Si and Al, promotes oxidation-induced amorphization, enabling the in-situ formation of a dense high-entropy oxide layer in 320 °C/16 MPa high-temperature water environment. This amorphous HEO exhibited shortened bond lengths and suppressed oxygen vacancy concentration via acceptor doping and atomic bonding regulation, serving as an effective diffusion barrier. Notably, the coating demonstrates exceptional resistance to 1200°C steam, forming a dense α -Al 2 O 3 -rich surface layer that effectively blocks oxygen ingress. This protection, augmented by in-situ formed silicides and a locally Zr-Si diffusion layer, leads to significantly lower mass gain. The designed high-entropy coating offers a robust strategy for accident-tolerant fuel claddings under both normal and severe accident conditions.