Superelastic NiTi scaffolds with extensively tuneable mechanical and mass transfer properties

Natural bones exhibit a substantial recoverable strain (ε_rec) of 2%‒4% and vary in mechanical and mass transfer properties across different body regions. Integrating these attributes is essential for the functionality and therapeutic efficacy of metallic scaffolds used in bone defect treatment. This study presents innovative superelastic nickel-titanium (NiTi) scaffolds with a remarkable maximum ε_rec of 6%‒7% and extensive tuneability in elastic modulus, cyclic stress, compressive strength, specific damping capacity, and permeability. These impressive performance integrations are attributed to carefully designed structures featuring stable austenite phases with hierarchical microstructures and gyroid-sheet macrostructures. Physical experiments and computational simulations illustrate that this unique structure combination promotes martensitic transformation during deformation and allows the tuning of mechanical and mass transfer properties without compromising superelasticity. The deformation-recoverable and performance-tuneable NiTi scaffolds are more adaptive than their conventional counterparts, offering a versatile solution for diverse bone implantation needs. In addition to scaffold applications, this study provides valuable insights for developing advanced multifunctional metamaterials applicable in other fields.