The effect of Mo interlayer on CeO2/Y2O3 reinforced AlCrFeNiCu high-entropy alloy coatings on Zr-4 substrate

Rare earth oxide (CeO₂/Y₂O₃) reinforced AlCrFeNiCu high-entropy alloy coatings with a Mo interlayer (designated as Mo/CeO₂-AlCrFeNiCu and Mo/Y₂O₃-AlCrFeNiCu) were successfully deposited onto a Zr-4 substrate via high-speed laser cladding. The microstructural characteristics and properties of the composite coatings were comprehensively investigated. The results demonstrate that the Mo interlayer alleviates the thermal mismatch between the substrate and the HEA coatings and, to a certain degree, counteracts the grain refinement effect induced by the rare earth oxides. Overall, it plays a critical role in enhancing interfacial structural stability, mitigating thermal stress, and improving overall coating performance. It effectively optimizes the coating-substrate bonding integrity, reduces susceptibility to high-temperature fretting fatigue and plastic deformation, and significantly lowers the specific wear rate. Furthermore, the Mo interlayer enhances the compactness and continuity of the interface, suppresses the formation of corrosive pathways, and promotes the formation of a thicker, more stable passive film on the coating surface.