Microstructure and mechanical properties of Co-free AlCrFeNiTi0.2 eutectic high-entropy alloy

The microstructure and mechanical properties of a novel Co-free AlCrFeNiTi0.2 eutectic high-entropy alloy (EHEA) are investigated. X-ray diffraction analysis, in conjunction with EDS and EBSD, reveals the presence of a typical eutectic microstructure comprising a Fe-Cr-enriched disordered A2 phase and an Al-Ni-enriched ordered B2 and/or L21 phase in the as-cast AlCrFeNiTi0.2. The SEM morphology of the EHEA exhibits a typical dendrite solidification microstructure with petal-like and sunflower-like shapes. The three phases have the same crystal orientation within a single dendrite, despite their distinct chemical compositions. The interweaving arrangement of the A2 and B2/L21 phases results in the EHEA exhibiting excellent mechanical properties, including hardness, compressive yield and ultimate strength, and compressive ductility. These properties are superior to those of most other HEAs containing Cr-Fe-Ni, with values of 588 HV0.2, 1499 MPa, 3335 MPa and 33.9%, respectively.