Cu-based alloys are known for their high corrosion resistance but with a lack of processing ability and vice versa. Here we present a novel alloy design concept realizing Cu-rich high entropy conventional alloy (HECA) having exceptional corrosion resistance (Ecorr = - 0.27 V, icorr = 2.83 × 10−6 A/cm2) and work hardenability (strength = 413 MPa, total elongation = 28 %) synergy simultaneously in as-fabricated state. This cocktailing effect in HECA (Cu-12Fe-8Mn-7.5Co-2.5Cr, all in at%) is attributed to the formation of Fe-Mn-Co-Cr containing high entropy phase (HEP) in the Cu-rich matrix. A pronounced two-phase hardening by hetero-deformation induced (HDI) strengthening effect at the HEP/Cu matrix resulted in excellent work hardenability whereas, exceptional corrosion resistance was attributed to delayed corrosion kinetics owing to the preferential corrosion of the Cu-rich phase over HEP in HECA. Thus, Cu-rich HECA overcomes the corrosion-strength ductility dilemma in Cu-rich alloys when compared with classical binary Cu-Fe alloys in an as-fabricated state.

Strength and ductility vary inversely due to a rapid decrease in dislocation storage capacity with the pronounced increase in work hardening rate at the expense of ductility in most conventional and recently designed advanced ductile materials. This limitation can be overcome by creating heterogenous or hierarchical microstructures containing not only presence but also different length scales of twins, bands, phases synergistically. In line of that, here we present Fe44Mn20Cr15Ni7.5Co6Si7.5 (all in at.%) compositionally complex alloy (M-CCA), which showed an exceptional increase in strength and ductility simultaneously as a result of hierarchical microstructuring that forms after conventional thermo-mechanical treatment. The increase in strength-ductility synergy is attributed to the occurrence of hetero-deformation induced (HDI) strengthening in early stage of deformation whereas planar slip assisted hetero-deformation banding, and deformation twinning in later stages of deformation during plastic straining. Hence, hierarchical microstructuring in M-CCA resulted in exceptional work hardening ability which is needed for structural integrity and manufacturing applications under tensile loads to suppress sudden failures during service.