Effect of Laser Energy Density on the Microstructure, Wear Resistance, and Corrosion Resistance of AlCoCrFeNi High-Entropy Alloy Coatings Fabricated by Laser Cladding on ATI 718Plus

To investigate the effects of laser energy density on the microstructure, phase constitution and distribution, wear resistance, and corrosion resistance of AlCoCrFeNi high-entropy alloy coatings, three coatings were fabricated on ATI 718Plus substrates by laser cladding at different laser energy densities. Their microstructure, phase constitution, microhardness, tribological behavior, and electrochemical corrosion properties were systematically characterized. The results showed that all coatings exhibited good metallurgical bonding with the substrate. With increasing laser energy density, the coating microstructure initially became finer and more homogeneous and subsequently coarsened. All coatings were primarily composed of BCC/B2 phases with a small fraction of the FCC phase. The coating produced at the medium laser energy density (MHI) exhibited the most homogeneous phase distribution and the highest average microhardness of 576.1 HV0.3. It also showed the lowest coefficient of friction and specific wear rate, with values of 0.52 and 6.94 × 10−4 mm3/(N·m), respectively. The dominant wear mechanism was abrasive wear, accompanied by localized delamination and tribo-oxidation. Furthermore, the MHI coating exhibited the highest charge-transfer resistance of 18,880 Ω·cm2 and the lowest corrosion current density of 96.8 μA·cm−2, indicating superior corrosion resistance. These results demonstrate that an appropriate laser energy density promotes a finer and more homogeneous solidification microstructure and a more favorable phase distribution, thereby achieving a synergistic improvement in the hardness, wear resistance, and corrosion resistance of AlCoCrFeNi high-entropy alloy coatings.