Microstructure and Properties of AlCoCrFeNi2.1 Eutectic High-Entropy Alloy Coatings Fabricated by Extreme High-Speed and Conventional Laser Cladding

AlCoCrFeNi2.1 eutectic high-entropy alloys (HEAs) are a new kind of alloy with high entropy and eutectic properties. Their advantages in terms of strength and shape matching can be fully exploited using extreme high-speed laser cladding (EHLA). In this paper, AlCoCrFeNi2.1 eutectic HEA coatings were prepared by conventional laser cladding (CLA) and EHLA. The microstructures and phase compositions of the two coatings were analyzed by scanning electron microscopy, x-ray diffraction, and electron backscatter diffraction. The microhardness and wear resistance values of the coatings were tested using a microhardness tester and a friction and wear tester, respectively. The results showed that the surface qualities of both the CLA and EHLA coatings were good and had no cracks or defects. Compared with those of the CLA coating, the EHLA coating had finer grains and a more uniform distribution. Both coatings contained face-centered cubic (FCC) and body-centered cubic (BCC) phases, but the BCC phase of the EHLA coating was less precipitated than the CLA coating. The higher microhardness and better wear resistance of the EHLA coatings occurred in the presence of Hall-Petch strengthening.