Bioinspired, heredity-derived hierarchical bulk multifunctional copper alloys

Bioinspired hierarchical design demonstrates a promising microstructural solution to circumvent multiple intricate property trade-offs in artificial materials. However, it remains extremely challenging to tailor structural hierarchies feasibly and synthetically, particularly for bulk materials. Here, a counterintuitive strategy is reported–exploring multiscale microstructural heredities for highly-developed dendritic hierarchies in as-cast bulk alloys. During optimized thermomechanical processing, we carefully control these dendrites to be progressively deformed, elongated, aligned and refined, rather than completely destroying them as in conventional alloy processing paradigms. As such, a hierarchical fibrous lamellar (HFL) structure–resembling those of shell and bamboo–is controllably designed in a technologically-important CuCrZr alloy. This innovative HFL design promotes multiple synergetic micro-mechanisms with sequential multiscale interactions and salient biomimetic attributes, thereby affording exceptional multifunctionality, especially record-high strength–ductility–conductivity combination. At more fundamental levels, multiple previously inaccessible deformation and reinforcement mechanisms are activated by exploiting the HFL structure-enabled complex internal stress condition. They perform and interact at multi-length-scales from intense diversified dislocation trapping, massive stacking-fault proliferation, 9R-phase-assited nano-twinning, self-buffering shear bands to ever-intensified hetero-deformation-induced hardening. These scenarios even create superior, strain-rate-tolerant dynamic properties far exceeding conventional homogeneous-structured counterparts. Dendrites exist ubiquitously, yet generally undesirable, in metallic materials, whereas our ‘bioinspired, heredity-derived’ strategy counterintuitively utilizes them, realizing unprecedented high figure-of-merit multifunctionality. © 2023 Shanghai University.