Design of bone-like continuous gradient porous scaffold based on triply periodic minimal surfaces

In this work, we designed a new bone-like scaffold with a continuous porosity gradient change based on minimal surfaces. Three minimal surface structures (P (Primitive), G (Gyroid), and D (Diamond)) were chosen to design the scaffolds, and the scaffolds were successfully prepared by selective laser melting using a new Ni46.5Ti44.5Nb9 alloy. The results show that the scaffolds have the matched low elastic modulus (1.5–3.4 GPa) and suitable strength (75–321 MPa) compared with human bone. The unit structure type has a considerable effect on mechanical properties and permeability, and the superiority order is P > G > D. The scaffold is more compact with lower porosity on the outside, where can bear more stress during compression, thus improving the mechanical properties of the scaffolds. The high porosity in the inner facilitates the flow of liquid, thus improving the permeability of the scaffold. This work provides a new method to design porous scaffolds in medical applications.