Microstructure and Tribology Performance of Plasma-Clad Intermetallic-Reinforced CoCrFeMnNi-Based High-Entropy Alloy Composite Coatings

摘要

In this article, the synergistic effect of the addition of V and Nb on CoCrFeMnNi high-entropy alloy (HEA) coating prepared by plasma cladding was studied. The results showed that the addition of V and Nb promoted the precipitation of intermetallics in the HEA coating and had no effect on the face-centered cubic (FCC) structure of the matrix. The CoCrFeMnNiVNb composite coating presented a complex phase structure including an FCC phase, FeNb intermetallic (Laves) phase, and CoFeV intermetallic (sigma) phase. Compared with the CoCrFeMnNi coating, the microhardness of the CoCrFeMnNiV, CoCrFeMnNiNb, and CoCrFeMnNiVNb coatings increased by 4.3, 4.2, and 6.5 times, respectively. The exceptional hardness was primarily attributed to the formation of hard intermetallics and solution strengthening of V and Nb. The synergistic reinforcement effect of V and Nb on the wear properties was better than that of a sole addition. The wear resistance of the CoCrFeMnNiVNb coating was the best, corresponding to the lowest wear rate of 1.85 x 10(-5) mm(3)center dot N-1 center dot m(-1). The addition of V and Nb restrained abrasive wear and adhesive wear and promoted the formation of oxide layers on the worn surface of the HEA coatings during sliding.