Phase separation induced heterostructure promotes strength-ductility synergy in Cu-rich compositionally complex alloy in as-cast state

Journal article, 2025

Dual-phase alloys (Cu-Fe alloys) exhibit excellent strength by dual-phase strengthening at the interface of harder and softer phases, at the expense of ductility. In an attempt to address this limitation in Cu-Fe alloys, a novel Cu-rich (Cu50Mn30Fe10Co10) compositionally complex alloy (all elements in at%, Cu-CCA) has been developed by merging compositionally complex alloy (CCA) design principles with classical phase separation mechanism. The as-cast Cu-CCA exhibits not only phase separation (α(f.c.c)→α1f.c.c.+α2(f.c.c)) but also possesses unprecedented strength-ductility (σUTS = 630 MPa, ε = 36 %) synergy. The occurrence of phase separation into a mixture of two f.c.c. phases is a result of intelligent alloy design whereas excellent strength-ductility synergy is facilitated primarily by hetero deformation induced (HDI) strengthening at the junctions of these separated phases during deformation. Thus, this identical phase separation in newly designed Cu-CCA overcomes the conventional strength-ductility paradigm in as-cast Cu and most of its binary/ternary alloys thereby making it a profound candidate for structural applications.