Engineering transformation pathways in an Al0.3CoFeNi complex concentrated alloy leads to excellent strength–ductility combination

Abstract

Guided by thermodynamic modeling, engineering phase transformation pathways via thermo-mechanical processing, in a complex concentrated alloy/high entropy alloy (HEA) of composition Al0.3CoFeNi, lead to a novel multi-scale microstructure consisting of fine-scale FCC + L12 grains mixed with B2 + BCC grains. The two-step pathway comprises initial decomposition of the parent single-phase FCC to form a fine-grained FCC + B2 microstructure, which further decomposes in the second step into the complex four-phase mixture, exhibiting an excellent combination of tensile yield stress of ∼1490 MPa, ultimate tensile strength of ∼1663 MPa, with a good ductility of ∼12% at room temperature.