A novel Co-free Al0.75CrFeNi eutectic high entropy alloy with superior mechanical properties

Eutectic high entropy alloys (EHEAs) with superior mechanical properties and good castability are one of the most promising candidates among high entropy alloys (HEAs) for engineering applications. In this study, a new Co-free Al0.75CrFeNi EHEA with a low density of similar to 6.56 g/cm(3) was designed and prepared, the soli-dification process and ambient deformation behavior of the alloy were investigated in detail. Al0.75CrFeNi was composed of a disordered body-centered cubic (BCC) phase and an ordered body-centered cubic (B2) phase, which grew alternately to form a beautiful sunflower-like eutectic morphology. The alloy exhibited excellent mechanical properties with a high yield strength (sigma(0.2)) of 1482 +/- 56 MPa, fracture strength (sigma(bc)) of 3639 +/- 190 MPa, and elongation to fracture of similar to 37.8% +/- 1.5%. The high strength and low density of the alloy lead to a superior specific yield strength of similar to 226 KPa.m(3)/kg. During deformation, dislocation gliding in the BCC phase dominated the plastic deformation in the early stage. Subsequently, the dislocation activated in the B2 phase when the strain was further increased. Dislocation interactions and microstructural features, such as grain boundaries and substructures, in different stages generated the good balance between the strength and the ductility of the alloy. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

Eutectic high entropy alloys (EHEAs) are a promising option for engineering applications due to their superior mechanical properties and good castability. In this study, a new Co-free Al0.75CrFeNi EHEA was designed and prepared, exhibiting excellent mechanical properties with a high yield strength, fracture strength, and elongation to fracture. The alloy's deformation behavior was dominated by dislocation gliding in the BCC phase, and dislocation activation in the B2 phase contributed to further strain increase. The alloy achieved a good balance between strength and ductility through dislocation interactions and microstructural features.