Structural Evolution and Performance Changes in FeCoCrNiAlNb_x High-Entropy Alloy Coatings Cladded by Laser

FeCoCrNiAlNb_x (x = 0, 0.25, 0.5, 0.75, and 1) high-entropy alloy (HEA) coatings were prepared by laser cladding to explore the effects of the addition of Nb on the microstructure and wear resistance properties of FeCoCrNiAlNb_x HEAs. These effects were analyzed by microstructure and wear performance tests. The experimental results show that the structure of FeCoCrNiAlNb_x consists of BCC and FCC phases at x = 0, 0.25, and 0.5. FCC₂ formed at x = 0.75, and Fe₂Nb was detected at x = 1. The content of FCC phase increased with the increasing content of Nb. At x = 0, 0.25, 0.5, 0.75, and 1, the average hardness values were 439, 685, 773, 672, and 561 HV, whereas the mass losses were 3.4, 1.9, 1.6, 2.3, and 2.5 mg after a sliding wear test against a WC ball, respectively. The hardness and wear resistance clearly increased initially and then decreased with the continuous addition of Nb. The wear resistance is highest for the alloy with x = 0.5. Thus, the effect of the addition of Nb should be considered and rationally determined before the preparation of FeCoCrNiAlNb_x HEA to improve the wear resistance.