Microstructure, Crystallographic Orientation and Mechanical Property in AlCoCrFeNi2.1 Eutectic High-Entropy Alloy Under Magnetic Field-Assisted Directional Solidification

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Microstructure, crystallographic orientation and mechanical properties in the AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) formed using magnetic field-assisted directional solidification were studied experimentally. An aligned eutectic structure formed using magnetic field-assisted directional solidification. Both eutectic lamellar spacing and eutectic cellular spacing decreased with the increasing growth speed and the application of a magnetic field. The crystallographic orientation relationship between FCC phase and BCC (B2) phase in AlCoCrFeNi2.1 EHEAs was investigated and only one orientation relationship, {110}BCC//{111}FCC〈1$$\overline{1}$$2〉BCC//〈11$$\overline{2}$$〉FCC was found. Significantly, the magnetic field-assisted directionally solidified AlCoCrFeNi2.1 EHEA possessed the highest elongation to failure (ef) relative to the same EHEA series reported so far. The ef reached about 45 pct with an ultimate tensile strength of ~ 1058 MPa. This enhancement in mechanical properties can be attributed to the microstructural modification caused by the directional solidification and/or the magnetic field, highlighting an effective pathway to achieve superior mechanical properties in EHEAs.