Formation and beneficial effects of the amorphous/nanocrystalline phase in laser remelted (FeCoCrNi)75Nb10B8Si7 high-entropy alloy coatings fabricated by plasma cladding

Abstract

High-entropy amorphous composite coatings have high potential application value in the industrial field due to their excellent performance. (FeCoCrNi)75Nb10B8Si7 high-entropy alloy coatings with amorphous/nanocrystalline phases were prepared by plasma cladding and subsequent laser remelting. The phase, microstructure, mechanical properties, and wear resistance of the coatings were studied. Detailed characterization indicated that the microstructure of the plasma cladding coating consisted of the body-centered cubic (BCC) phase, whereas that of the laser remelting coatings consisted of the Fe and Ni-rich BCC phase in the dendritic area and the Nb, B, and Si-rich nanocrystalline-face-centered cubic (nano-FCC) + amorphous phases in the interdendritic area. Excellent mechanical properties were observed, including high microhardness, high nanohardness (H) to elastic modulus (E) ratio (H/E), high H3/E2, and a high elastic recovery rate (η). Furthermore, the coefficient of friction (COF) was lower in the laser remelting coatings (0.6) than in the plasma cladding coating (0.7), which was attributed to severe adhesive wear of the plasma cladding coating and abrasive and slightly adhesive wear of the laser remelting coatings. The microstructure evolution and strengthening contribution of the interdendritic structure in the laser remelting coatings and the relationship between the microstructure and mechanical properties and wear resistance were analyzed.