Microstructure and tribological properties of laser clad γ/Cr7C3/TiC composite coatings on γ-TiAl intermetallic alloy |
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| Affiliation: | 1. Laboratory of Laser Intelligent Manufacturing, Institute of Mechanics, Chinese Academy of Sciences, 15 Beisihuanxi Road, Beijing 100080, PR China;2. School of Materials & Chemical Engineering, Zhongyuan Institute of Technology, 41 Zhongyuan Western Road, Zhengzhou 450007, Henan Province, PR China;3. Laboratory of Laser Materials Processing & Manufacturing, School of Materials Science and Engineering, Beihang University, 37 Xueyuan Road, Beijing 100083, PR China;1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;2. School of Metallurgy and Environment, Central South University, Changsha 410083, China;1. School of Materials Science and Engineering, Xi’an University of Technology, Xi’an, 710048, China;2. Joining and Welding Research Institute, Osaka University, Osaka, 567-0047, Japan;1. State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science, Lanzhou 730000, China;2. Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China;1. Institute of Marine Material Science and Engineering, Shanghai Maritime University, Shanghai 201306, PR China;2. Logistics Engineering School, Shanghai Maritime University, Shanghai 201306, PR China |
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| Abstract: | In order to improve the wear resistance of the γ-TiAl intermetallic alloy, microstructure, room- and high-temperature (600 °C) wear behaviors of laser clad γ/Cr7C3/TiC composite coatings with different constitution of NiCr–Cr3C2 precursor-mixed powders have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS), block-on-ring (room-temperature) and pin-on-disk (high-temperature) wear tests. The responding wear mechanisms are discussed in detail. Results show that microstructures of the laser clad composite coatings have non-equilibrium solidified microstructures consisting of primary hard Cr7C3 and TiC carbides and the inter-primary γ/Cr7C3 eutectic matrix, about three to five times higher average microhardness compared with the TiAl alloy substrate. Higher wear resistance than the original TiAl alloy is achieved in the clad composite coatings under dry sliding wear conditions, which is closely related to the formation of non-equilibrium solidified reinforced Cr7C3 and TiC carbides and the positive contribution of the relatively ductile and tough γ/Cr7C3 eutectics matrix and their stability under high-temperature exposure. |
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