Microstructure and Mechanical Properties of Multi-Phase Reinforced MoFeCrTiWNb2.5(Al2O3)x High-Entropy Alloy Laser Cladding Coatings

In this study, high-entropy alloy coatings, based on MoFeCrTiWNb2.5(Al2O3)(x) (x = 0.4, 0.45, 0.5, 0.55, 0.6), were successfully fabricated on the surface of an M2 high-speed steel by laser cladding. The addition of Al2O3 promoted the formation of a eutectic microstructure. When x < 0.5, the coatings had a hypoeutectic structure with a proeutectic BCC phase. When x > 0.5, the coatings formed hypereutectic alloys with a proeutectic Laves phase. When x = 0.5, the coating had a typical eutectic lamellar microstructure with a hardness of 775 HV0.2. The microstructure and property evolution of MoFeCrTiWNb2.5(Al2O3)(0.5) coatings treated for 6 h at different annealing temperatures of 750-1050 degrees C were investigated. The phase structure remained unchanged after annealing. The MoFeCrTiWNb2.5(Al2O3)(0.5) coating is a typical lamellar eutectic microstructure, exhibiting excellent microstructural stability at 750 degrees C. When the annealing temperature exceeded 850 degrees C, the hardness and wear resistance of the coating decreased. The hardness of the coating remained 582 HV0.2 after annealing at 1050 degrees C for 6 h, indicating that the coating had excellent high-temperature softening resistance.

Automated summary

In this study, high-entropy alloy coatings were successfully fabricated on the surface of high-speed steel using laser cladding technology. The addition of Al2O3 promoted the formation of a eutectic microstructure, with different compositions resulting in hypoeutectic or hypereutectic structures. The phase structure remained unchanged after annealing at temperatures ranging from 750 to 1050 degrees C. The coating exhibited excellent microstructural stability at 750 degrees C, while the hardness and wear resistance decreased at temperatures above 850 degrees C.