Manufacturability and mechanical properties of Ti-35Nb-7Zr-5Ta porous titanium alloys produced by laser powder-bed fusion

Porous titanium alloys with low modulus are in high demand for medical implants. In this study, laser powder-bed fusion (LPBF) was used to create biomedical Ti-35Nb-7Zr-5Ta (wt.%; TNZT) porous titanium alloys. The relationships between the processing parameters, forming quality, and performance were established. The results revealed that increasing the scanning speed or decreasing the laser power allowed the manufacturing deviation of the porous titanium alloys to be reduced and become closer to the design value. However, excessively high or low laser energy can cause internal defects. The optimal processing parameters for eliminating defect porosity in porous titanium alloys required an energy density lower than that required for the LPBF of fully dense materials. Additionally, high scanning speeds weakened texture and refined grains, which in turn decreased the yield strength and hardness, owing to the formation of the β' phase with large lattice distortion. Porous titanium alloys prepared with optimal processing parameters exhibited a low modulus and exceptional energy absorption capabilities, prominently positioning in the modulus-energy absorption spectrum compared with reported lattice structures. This study offers valuable guidelines for the development of novel biomedical titanium alloys and the engineering applications of porous TNZT alloys.