Realizing strength-ductility combination of Fe3.5Ni3.5Cr2MnAl0.7 high-entropy alloy via coherent dual-phase structure

A coherent dual-phase structure in Fe3.5Ni3.5Cr2MnAl0.7 high-entropy alloy (HEA) was obtained through vacuum arc-melting and subsequently homogenizing. The microstructure and mechanical properties of as-homogenized Fe3.5Ni3.5Cr2MnAl0.7 HEA were examined. Fe3.5Ni3.5Cr2MnAl0.7 HEA is composed of dual phases, face-centered cubic (FCC) matrix phase and body-centered cubic (BCC) minor phase, the relationship between them meets the Kurdjumov-Sachs orientation. The chemical composition of FCC matrix phase is close to the designed composition of the studied alloy, while that of BCC phase is in nickel- and aluminum-rich. The as-homogenized Fe3.5Ni3.5Cr2MnAl0.7 HEA has excellent comprehensive mechanical properties, with an excellent combination of yield strength (650 MPa) and elongation (22.8%), which is attributed to the synergic effect of soft FCC phase and hard BCC phase with coherent relationship during plastic deformation.