Microstructures and mechanical properties of CrFeNi2Nbx eutectic multicomponent alloys

Highlights: • Co-free eutectic high entropy alloys of CrFeNi₂Nb_x. • Microstructure evolution from hypoeutectic to hypereutectic microstructure as increasing Nb content. • Ultrafine full eutectic lamellar structure with FCC and Laves phase in CrFeNi₂Nb_0.6. • Compressive maximum fracture stress of 2060.6 MPa and strain 14.4%. -- Abstract: The effects of Nb content on microstructures and resultant mechanical properties in Co-free CrFeNi₂Nb_x (x = 0, 0.2, 0.4, 0.55, 0.6, and 0.8) eutectic multicomponent alloys were investigated at room temperature. With increasing Nb content, the initial microstructure of a single face-centered cubic phase varied from hypoeutectic (0.2 0.6) with the formation of Fe₂Nb-type Laves phase, and the compressive strength and hardness increased at the expense of ductility reduction. Although the overall mechanical properties of the alloys were inferior to those of Co-containing CoCrFeNiNb_x alloys, a comparable maximum fracture strength (2060.6 MPa) was achieved in the CrFeNi₂Nb_0.6 alloy, which showed an ultrafine full eutectic lamellar structure.