Study on the microstructure, hardness and corrosion resistance of laser clad AlCoCrFeNiCu High-Entropy alloy coatings

Purpose The aim of this study is to investigate the effects of the laser cladding process on the microstructure, hardness and corrosion resistance properties of high-entropy alloys (HEA). Design/methodology/approach Laser cladding technology was used, using AlCoCrFeNiCu HEA powder as the cladding material. HEA coatings were prepared on the surface of 45 steel using a coaxial powder feeding method. The microstructure, phase composition, hardness and corrosion resistance properties of the HEA cladding layer were analyzed using optical microscopy (OM), X-ray diffractometer, digital microhardness tester and electrochemical workstation. Findings Laser power affects the coating surface; lower power reveals more visible unmelted powder particles. Higher power results in increased melt width and height, a brighter, smoother surface. Phase structure remains consistent, but the coating hardness is significantly higher than the substrate. The hardness of the melted zone in the substrate peaks at approximately 890.5 HV. The cladding zone hardness is about 60 HV higher than the substrate zone. Electrochemical corrosion parameters of the cladding show that, compared to the substrate, Ecor shifts positively by 113 mV, Icor decreases by one order of magnitude and Rp increases by one order of magnitude. These results indicate that the cladding has superior corrosion resistance to the substrate. The bonding strength between the coating and the substrate is greater than 93.6 MPa. Originality/value First, based on preliminary pilot experiments, nine sets of single-factor experiments were designed. Through these experiments, a specimen with relatively favorable cross-sectional morphology was observed. This specimen was then subjected to coating research, revealing that its microstructure and properties had significantly improved compared to the substrate. This enhancement holds remarkable significance for prolonging the service life of components. Peer review The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-11-2024-0413/