Microstructure Characterization of a New-Type Eutectic Medium-Entropy Alloy Cofesnni1.5

Abstract

A series of CoFeSnNix medium-entropy alloy was designed and prepared. This as-cast alloy has a unique lamellar eutectic solidification pattern. The eutectic medium-entropy alloys are transformed from hypoeutectic to hypereutectic solidification by increasing Ni content. Through a series of experimental characterization and theoretical analysis, the lattice structure and element composition was identified. The new eutectic medium-entropy alloy was composed of face-centered cubic and hexagonal close-packed solid solutions. This type of eutectic structure was rarely reported in multicomponent alloys. Designing rules of multi principal alloys were applied to the current work but the results indicated that existing theories cannot predict phase formation effectively. The new-type eutectic medium-entropy alloy may serve as a reference for the development of new theories in the future.

Keywords: Medium-entropy alloy, Lamellar eutectic dendrite, Alloy design, Microstructure