Design of novel structural eutectic high entropy alloys (EHEAs) containing high-temperature resistant alloying elements

This article employs the "Simple Mixing Enthalpy Method" to add high-temperature alloying elements Mo/V and Nb to the Fe-Co-Cr-Ni-based alloy system, and utilizes a model of the relationship between elements and phase structures. Finally, EHEAs are successfully designed with the help of phase diagrams, namely FeCoNi2.0Cr1.2Mo0.2Nb0.63 (Mo 0.2 Nb 0.63 ) and FeCoNi2.0Cr1.2V0.2Nb0.68 (V 0.2 Nb 0.68 ). In EHEAs, a typical fully eutectic microstructure is observed, consisting of alternating FCC (face-centered cubic) and HCP (hexagonal close-packed) phases. Evaluation of mechanical performance indicators reveals that nano-hardness and elastic modulus increase from the FCC phase to the HCP phase, while the hardness and elastic modulus of the eutectic phase originate from modulation of these two phases. Meanwhile, the microhardness of both alloy systems increases linearly with increasing Nb content. In addition, EHEAs exhibit high strength and ductility but with differences attributed to the significant influence of Mo and V elements on eutectic phase spacing and phase size. Different phase interface types and strain gradients during deformation affect the mechanical properties. This study tests the high-temperature compression performance and fracture morphology of novel high-entropy alloys, paving the way for subsequent research on high-temperature performance.