Ultralight High-Entropy Nanowire Scaffolds for Extreme-Temperature Functionality

High-entropy alloys (HEAs) combine compositional disorder with exceptional functional tunability, yet their inherently high density limits their use in lightweight systems. Here, we introduce entropy-architected nanowire metamaterials, a class of materials that couple configurational entropy with structural porosity to achieve a metal-like functionality at ultralow density. FeCoNiCrCu HEA nanowires were electrodeposited into porous templates and freeze-cast into three-dimensional "bird's nest" scaffolds with densities below 1% of the bulk metal. The resulting architectures retain a disordered face-centered-cubic phase, exhibit Curie temperatures exceeding 1000 K, and deliver thermal diffusivity (≈0.211 mm² s⁻¹) comparable to titanium alloys. Structural and spectroscopic analyses reveal nanoscale Cu segregation that enhances magnetic ordering and thermal stability. These findings demonstrate that configurational entropy and architectural hierarchy can be coengineered to yield lightweight, high-temperature functional materials for extreme-environment applications.