Fabricating polymer/HEA-hybrid topological lattice structure for enhanced mechanical properties

Metamaterials such as architected lattice structures have aroused broad interest in being applied as mechanical supports for their lightweight and custom-shaped capabilities.Although various prior efforts have been devoted,a multiscale fabrication of micro-nano lattice structures without penalizing the mechanical proper-ties is still a challenging but highly desirable task.Here we put forward a strategy to produce a mechanically enhanced micro-nano lattice structure by conformally depositing a CoCrFeNiTi high-entropy alloy(HEA)coating layer onto a three-dimensional(3D)printed polymer skeleton.The template for the 3D printing employs a six-membered tricapped trigonal prism(6M-TTP)structure derived from a medium-range order structure motif in amorphous alloys.The topological complexity of the 6M-TTP can substantially avoid the stress concentration by offering stress-release channels,while the HEA film incorporating with amorphous and nanocrystalline constituents can further reinforce the lattice architecture through its size hardening effect.Benefitting from the above,the fabricated polymer/HEA-hybrid lattice exhibits a high specific compressive strength(～0.055 MPa kg1 m3 at a density below 500 kg m-3),a superior elastic recoverability(～70％recovery rate under＞30％compression),an enhanced plasticity(40％strain)and a high specific modulus(0.135 MPa kg-1 m3).Our strategy initiates a perspective way to fabricate multiscale micro-nano lattice structures with improved mechanical properties,which could be extended to widespread metamaterial research.