PNNL

Abstract

Guided by thermodynamic modeling, engineering phase transformation pathways via thermo-mechanical processing, in a complex concentrated alloy (CCA) / high entropy alloy (HEA) of composition Al0.3CoFeNi, leads 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 a tensile yield stress of ~1490 MPa, ultimate tensile strength of ~1663 MPa, with a good ductility of ~12% at room temperature.