Preparation of Nano-bridged Honeycomb Microstructure Eutectic High-Entropy Alloy Coating with Excellent Corrosion Resistance by Laser Cladding

In this paper, AlCoCrFeNi_2.1 eutectic high-entropy alloy (EHEA) coatings with nano-bridged honeycomb microstructure were prepared by laser cladding. The results indicate a strong metallurgical bond between the coating and the substrate, with no obvious cracks or pores in the cross-section morphology. Through the dilution effect of laser cladding, AlCoCrFeNi_2.1 EHEA changes to a honeycomb structure from a typical lamellar structure, and the content of the BCC phase decreases. Furthermore, the EHEA coating has better electrochemical corrosion performance, higher self-corrosion potential and lower passivation current density in 3.5% NaCl solution compared with the substrate material. This is due to the formation of the Cr₂O₃ passivation film on the surface of EHEA coating during the corrosion process, which mainly exhibits a corrosion mode from pitting to linear corrosion as the corrosion progresses.