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Sayyed Erfan Aghili(1,2), Morteza Shamanian(1), R. Amini Najafabadi(3), Ali Keshavarzkermani(2), Reza Esmaeilizadeh(2), Usman Ali(2), Ehsan Marzbanrad(2), Ehsan Toyserkani(2)
Ceramics International, 46, Issue 2, February 2020: 1668-1679. DOI: 10.1016/j.ceramint.2019.09.139
Powder-fed laser cladding, Additive manufacturing, Oxidation, NiCr–Cr3C2, Titanium aluminide, Oxidation mechanism
In the present study, a NiCr–Cr3C2 powder mixture was prepared by mechanical alloying and then coated on titanium aluminide substrates by the powder-fed laser cladding process using a set of optimum parameters. The high temperature oxidation behavior of the substrate and coating was studied by isothermal annealing at 900 °C for 5 h. It was found that the microstructure of the coating is composed of γ solid solution with different chromium carbide phases (Cr3C2, Cr7C3 and Cr23C6). The presence of different chromium carbides in the microstructure of coating can be attributed to the partial melting of primary Cr3C2 and the formation of nonequilibrium carbide phases during rapid cooling of laser cladding. The NiCr-chromium carbide laser cladded coating samples showed superior oxidation resistance compared to the substrate. The oxidation mechanism of both coating and substrate follow the parabolic law, where the parabolic rate constant of the coating was 20% of that of the substrate at 900 °C. Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) and Grazing Angle X-Ray Diffraction (GAXRD) analysis revealed that the surface of the oxide layer formed on the NiCr-chromium carbides coating and the substrate is mostly composed of Cr2O3 and TiO2, respectively.
Dragonfly was used to analyse the final 3D image of the NiCr-chromium carbides.
(1) Department of Materials Engineering, Isfahan University of Technology, 84156-83111, Isfahan, Iran.
(2) Multi-Scale Additive Manufacturing Lab, Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
(3) Department of Metallurgy and Materials Engineering, Golpayegan University of Technology, Golpayegan, Iran.
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