Enhancing high-temperature fretting wear resistance of Ti-64 alloy by laser cladding FeCrAlMo_xNb_y high entropy alloy coatings

Fretting wear is the main factor restricting the application of titanium alloy as compressor blades. Preparing a kind of high entropy alloy (HEA) coating is an effective way to improve the fretting wear resistance under high temperature conditions. Thus, in the present work, the FeCrAlMo_xNb_y HEA coating was fabricated on a Ti-64 substrate by the laser cladding technology. The phase composition, microstructure and fretting wear resistance of the coating at high temperatures (200 °C, 300 °C and 400 °C) were investigated. It was demonstrated that the laser cladding FeCrAlMo_xNb_y HEA coatings exhibited dense and uniform microstructures consisting of a BCC phase and a Laves phase (Cr₂Nb). In addition, the changing trend of phase content of BCC and Laves phase is the same as the trend of atomic content of Mo and Nb respectively. The presence of the Laves phase increases the hardness of the coating. Due to its high hardness and the formation of a protective oxide layer, the coating demonstrated significantly superior resistance to high-temperature fretting wear compared to the substrate. The lowest wear rate is Mo_0·5Nb_0.5 coating at 300 °C, only 1.3 × 10⁻⁶ mm³/N·m. The current results provide a new method to protect titanium alloy's surface from fretting wear damage in high-temperature service environments.