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| Effects of TiN Content on Microstructures and Properties of Ti0.8 CoCrFeNiAl0.5 High-Entropy Alloy Composite Coating |
| HU Ji, SUI Xinmeng, ZHANG Lin, ZHAO Wei, ZHANG Weiping |
| Dalian University of Technology, Dalian 116024, China |
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Abstract The work aims to further enhance the microhardness and wear resistance of high-entropy alloy (HEA) Ti0.8 CoCrFeNiAl0.5. The Ti0.8 CoCrFeNiAl0.5/TiN composite coatings with different TiN contents were prepared on the surface of TC21 by laser cladding. The microstructures and phases of cladding layer were analyzed with scanning electron microscopy (SEM), X–ray diffractometry (XRD) and electron probe microanalysis (EPMA). The hardness distribution and wear resistance of the cladding layer are characterized by the microhardness tester and the material surface comprehensive performance tester. The results showed that the cladding layer is formed well and has good metallurgical bonding. Without TiN, the cladding layer is mainly composed of BCC1, FCC, Laves phases and β–Ti. After adding TiN, TiN particles precipitate in-situ in the cladding layer. The cladding layer is mainly composed of dendritic structure of BCC1 phase rich in Al–Co–Ni–Ti, interdendritic structure of BCC2 phase rich in Fe–Cr–Ti and Laves phase, β–Ti and TiN particles embedded between dendritic structure and interdendritic structure. The microhardness of the cladding layer increases to more than 2 times of the substrate, and the hardness of the cladding layer with 8% TiN is 1.23 times of the sample without TiN. When the content of TiN is 6%, the wear resistance is high, which is about 2.92 times that of the sample without TiN. It reveals that the addition of TiN is beneficial to the precipitation of TiN particles and the formation of BCC phase in the cladding layer, which can effectively improve the hardness and wear resistance of the cladding layer.
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2021, 
