A new CrFeNi2Al eutectic high entropy alloy system with excellent mechanical properties

A low-cost Co-free CrFeNi(3-x)Alx (x = 1, 0.9, 0.8, 0.7, 0.6) eutectic high entropy alloy (EHEA) system was designed, successfully prepared and characterized. With the increase of Al content, the alloy dramatically transforms from a hypoeutectic to a hypereutectic microstructure together with an increase in strength and a decrease in ductility. The CrFeNi2.2Al0.8 alloy was found to be an eutectic high entropy alloy and was composed of face centered cubic (FCC) phase and ordered body centered cubic (B2) phase. The hypereutectic CrFeNi2Al alloy shows excellent mechanical properties with an ultimate strength of 1357 MPa and a total elongation of 6.4% at the cast condition. The excellent mechanical properties of this EHEA system can be attributed to the nanolamellar microstructure and suggests a great potential application in the engineering field. We also propose a simple strategy to design Co-free EHEAs and predict more than ten potential Co-free EHEAs to guide experimental searches.