The Precipitation Behavior in Al0.3CoCrFeNi High-Entropy Alloy Affected by Deformation and Annealing

Abstract

The effects of deformation and annealing on the precipitation behaviors, including the structure and chemical composition of the L12, B2, BCC and σ phases, in Al0.3CoCrFeNi high entropy alloy were analyzed. Firstly, the thermodynamic factors controlled the precipitation pathway in as-cast alloys, which led to the L12 precipitating homogeneously in the FCC matrix under a low annealing temperature, while the B2 precipitated under a high annealing temperature. In contrast, if the deformation was introduced before annealing, the precipitation pathway of the second phase was completely changed to the B2, BCC and σ phases because of the combination of thermodynamic and kinetic conditions. In particular, the B2 and σ phases promoted the precipitation behavior reciprocally due to the complementary chemical compositions. The elaborate precipitation behaviors of the L12, B2, BCC and σ phases were analyzed to identify the phase transformation in the Al0.3CoCrFeNi HEA. These transformation pathways and elaborate structural features of the L12, B2, BCC and σ phases provide various design possibilities for the microstructures and properties of single FCC HEAs.