Design of a new eutectic high-entropy/multicomponent alloy by a single experiment of electromagnetic directional crystallization and the verification method

Abstract

Eutectic high-entropy alloys (EHEAs) or eutectic multicomponent alloys have been widely studied recently owing to their unique microstructure and excellent properties; however, the accurate and efficient design of new EHEAs remains a great challenge. To solve this problem, based on the precipitation principle of phases in a eutectic alloy phase diagram, we propose using a single experiment of electromagnetic directional crystallization (EDC) to separate a non-eutectic alloy melt to design a new EHEA. A new EHEA, Al_17.74Co_12.02Cr_13.70Fe_11.65Ni_44.89, was successfully designed by separating a non-eutectic alloy melt, AlCoCrFeNi₃, into eutectic and non-eutectic parts. Similarly, another EHEA, Al_17.89Co_12.20Cr_13.28Fe_11.10Ni_45.52, was also designed by separating a near-eutectic alloy melt, Al_16.8Co_12.6Cr_13.8Fe_11.8Ni_45.1. In particular, a criterion to verify whether an alloy is eutectic has been proposed: the eutectic alloy melt cannot be separated into different parts by EDC, and the composition of the eutectic alloy ingot along the direction of the EDC must not change significantly. Based on this criterion, a single EDC experiment can be used to verify whether an alloy is eutectic or non-eutectic. In addition, EDC also has great potential in improving the properties of EHEAs. The ultimate tensile strength and elongation of the EDC Al_17.74Co_12.02Cr_13.70Fe_11.65Ni_44.89 ingot were 1192.0 MPa and 17.0 %, respectively, and those of EDC Al_17.89Co_12.20Cr_13.28Fe_11.10Ni_45.52 alloy ingot were 1225.6 MPa and 17.0 %, respectively. Both designed new EHEAs possess a good combination of strength and ductility.