Microstructure and tensile behaviors of FCC Al0.3CoCrFeNi high entropy alloy

Homogeneously spherical nanoprecipitates with a L12 ordered structure are observed in as-cast FCC Al0.3CoCrFeNi high entropy alloy, while their morphology changes to platelets after aging at 700 °C. The appearance of a yield drop and low work-hardening during tension reveals that these nanoprecipitates are coherent and have the characteristics of the Guinier–Preston zone. The 900 °C aged alloy displays micro-sized rod-shaped precipitates rich in Ni and Al instead of nanoprecipitates. There is no yield drop but high work-hardening occurs during tension. This rod-shaped phase has a B2 ordered structure and has the Kurdjumov–Sachs relationship with the FCC matrix.