An additively manufactured high-entropy alloy with superior wear resistance by nanoprecipitation and high density dislocations

Posttreatment during additive manufacturing (AM) can augment the mechanical properties of materials, especially in the annealing regime of high-entropy alloys (HEAs). In the present research, we fabricated FeCoNiCrMo0.5 HEAs using different printing powers by exploiting the ultrahigh cooling rate characteristics of laser powder bed fusion technology and compared the microstructures, mechanical properties, and wear resistance properties of the printed and annealed specimens at 500 degrees C and 1000 degrees C. Concurrently, the increase in printing power diminished the presence of inherent defects and enhanced the material's surface properties, reducing the material's average friction coefficient. Notably, the increase in annealing temperature induced the precipitation of Mo-rich sigma phases, whose number, size, and shape varied considerably with temperature, further amplifying the surface hardness. Concretely, the interaction of the precipitated phases with the high density of dislocations elicited a strain hardening effect, bolstering the substrate's fracture toughness, and leading to a change in the form of wear and an increase in wear resistance. These findings elucidate the wear resistance behavior of the precipitated phase in the AM process of FeCoNiCrMo0.5 HEA, increasing the potential of HEAs for industrial applications.