Bulk nanostructured intermetallic alloys enable superb strength-ductility synergy and thermal stability

Grain refinement down to the nanoscale can significantly enhance the strength of alloys but inevitably leads to serious plastic and thermal instability. The conventional design of bulk nanograined (NG) alloys is mainly relied on disordered solid solution systems and fails to overcome such a thorny challenge. Here, we innovatively engineer the nanostructured chemically complex intermetallic alloys (CCIMAs) dominated by an ordered superlattice structure. A bulk boundary-decorated bimodal nanostructured (BBN) CCIMA, composed of nano-subgrains and ultrafine grains with disordered interfacial nanolayers, was controllably synthesized by simple thermo-mechanical treatment. This newly designed alloy exhibits record-high yield strength-uniform elongation combinations of 1.83 GPa-14% and 2.19 GPa-13% at ambient and cryogenic temperatures, respectively. Such superb mechanical properties mainly stem from superlattice stacking faults (SSFs)-enhanced defect accumulation, therefore contributing to an exceptional work-hardening capability. Additionally, this alloy demonstrates an unexpected thermal resistance to grain coarsening at elevated temperatures up to 900 ℃. Our findings demonstrate an innovative approach to developing ultrahigh-performance NG alloys for extreme environments.