Rapid Design, Microstructures, and Properties of Low-Cost Co-Free Al-Cr-Fe-Ni Eutectic Medium Entropy Alloys.

In this study, we establish a mathematical rule for accelerating the prediction of low-cost Co-free AlCrFeNi FCC/B2-structured eutectic medium entropy alloys (EMEAs). The mathematical formulas are c ≥ 1.0, 4.38a + 4.28b + 3.97c ≈ 20.55, and c - a ˃ 1.0. With this rule, we successfully predict the AlCrFeNi and AlCrFeNi eutectic alloys and verify their eutectic morphology by experiments. Both the AlCrFeNi and AlCrFeNi EHEAs exhibit excellent compressive mechanical properties, with yield stress higher than 500 MPa, compressive fracture strength higher than 2450 MPa, and fracture strain > 40%, which can be attributed to their unique lamellar microstructure. Moreover, both alloys exhibit good corrosion resistance in 3.5 wt.% NaCl solution. Among them, the AlCrFeNi EHEA exhibits better corrosion resistance due to the higher content of the FCC phase.