Microalloyed medium-entropy alloy (MEA) composite nanolattices with ultrahigh toughness and cyclability

Three-dimensional nanolattices have recently emerged as an effective strategy to achieve high strength at low densities, by harnessing the combination of rationally designed topologies and nanoscale size effects [1-5]. However, most metallic and ceramic nanolattices show an ineludible deterioration of mechanical properties upon repeated loading due to localized brittle fracture. Here, by development and deposition of CoCrNiTi0.1 microalloyed medium-entropy alloy (MEA) with extra low stacking fault energy, we fabricated ultratough MEA-coated nanolattices that can exhibit unprecedented surface wrinkling under compression. Particularly, nanolattices with alloy film thickness similar to 30 nm can repeatedly withstand strains exceeding 50% with negligible strut fracture, while the elastic polymer core promotes recoverability and structural integrity. Furthermore, owing to the high strength of the metallic film, our MEA composite nanolattices exhibited high energy absorption (up to 60 MJ m(-3)) and specific strength (up to 0.1 MPa kg(-1) m(3)), offering a plethora of robust micro/nano-mechanical and functional applications.