Unveiling the TiZrNbTaFeC_x high entropy alloy carbide coatings fabricated by superimposed HiPIMS-MF technique- effect of carbon contents on the microstructure, mechanical properties, and corrosion resistance

In this research, TiZrNbTaFe high entropy alloy (HEA) and five TiZrNbTaFeC_x HEA carbide coatings with different carbon contents were fabricated by a superimposed HiPIMS-MF system under different C₂H₂ gas flow rates. The phase structure of the coating changed from amorphous to FCC at 32.40 at.% carbon. Hardness increased from 7.7 to 22.1 GPa as the carbon content increased from 0 to 32.40 at.%, then decreased to 19.5 GPa at 35.78 at.% C due to too much soft amorphous carbon phase. The HEA coating with the highest carbon content of 35.78 at.% exhibited the best wear resistance, with a lower coefficient of friction of 0.21 and the lowest wear rate of 3.80 × 10⁻⁶ mm³N⁻¹m⁻¹. According to the potentiodynamic polarization and electrochemical impedance spectroscopy tests, the TiZrNbTaFe coating exhibited excellent corrosion resistance in 0.5 M H₂SO₄, which is 802.7 times better than that of bare AISI 52100. We can conclude that the 35.78 at.% C contained TiZrNbTaFeC HEA carbide coating exhibited a hardness of 19.5 GPa, excellent tribological performance, and the second-best corrosion resistance, which can be used in severely corrosive and stress bearing environments.