Mechanical properties of large-size AlCoCrFeNi2.1 eutectic high-entropy alloy via hot-rolling followed by annealing

Abstract:
Large-size AlCoCrFeNi2.1 eutectic high-entropy alloy (EHEA) was successfully deformed by hot-rolling. The effects of hot-rolling and annealing on the microstructure and mechanical properties were investigated. After 70% reduction at 800 °C, B2 precipitate formed in FCC matrix, with the yield strength of 1012±19 MPa, tensile strength of 1326±53 MPa and total elongation of 9.0±3.5%. With increasing annealing temperature from 800 to 1200 °C, the strength decreased and the elongation increased, exhibiting a strength-ductility compromise. However, when annealing at 600 °C, the mechanical properties were enhanced with the yield strength of 1084±3 MPa, tensile strength of 1500±5 MPa, and total elongation retained. Through two-step annealing at 1000 °C + 600 °C, the EHEA showed the best strength-ductility balance, with the yield strength of 838±7 MPa, tensile strength of 1417±4 MPa and total elongation of 14.2±0.3%. The result shows that hot-rolling followed by two-step annealing can simultaneously improve the strength and plasticity of the AlCo- CrFeNi2.1 EHEA.