A self-optimized alloy with multi-scale hierarchical microstructure and enhanced mechanical properties

Recent years have witnessed a transformative shift with the advent of high entropy alloys (HEAs), liberating the constraints on the composition of high-strength alloys. Nevertheless, the composition design of most HEAs still relies on "trial-and-error" approaches either experimentally or computationally. Given the expansive composition space inherent to HEAs, the conventional "trial-and-error" method poses a formidable challenge in pinpointing potential high-performance HEA compositions. Here, we implement a "self-optimizing" strategy to minimize the arduous "trial-and-error" approach. The "self-optimizing" strategy involves identifying the chemical composition of supersaturated single solid-solution phases by directly using the local compositions of specific phase constituents within existing multicomponent alloys containing dual or multiple phases. The "selfoptimized alloy" exhibits enhanced tensile mechanical properties with a yield strength of around 1.2 GPa and appreciable ductility up to around 10%. The enhanced yield strength stems from a unique multi-scale hierarchical microstructure and the resulting multistage deformation behaviour and integrated strengthening effects. The strategy of "self-optimized alloy" design and hierarchical microstructure control are readily applicable to other existing dual-phase or multi-phase alloys, expediting the exploration of novel advanced engineering materials.