Porous bio-high entropy alloy scaffolds fabricated by direct ink writing

Porous tantalum-titanium-niobium-zirconium (Ta-Ti-Nb-Zr) bio-high entropy alloy (bioHEA) scaffolds are fabricated using direct ink writing 3D printing technology in this study. A composite ink is prepared using four metal powders as raw materials: Ta, Ti, Nb and Zr. Ink extrusion is used to build 3D scaffolds with interconnected porous structures at room temperature, which are then sintered in a vacuum environment. The interdiffusion of metal elements yields porous bioHEA scaffolds with a body-centered cubic (BCC) structure. The fabricated scaffolds have uniform compositions with a significant alloying effect and good biocompatibility. The scaffolds have a compressive strength of 70.08-149.95 MPa and an elastic modulus of 0.18-0.64 GPa, indicating that the mechanical properties can be controlled over a wide range. The scaffolds have a compressive strength close to that of human cortical bone and thus meet the requirements for porous structure characteristics and biological and mechanical properties of orthopedic implants.