Influence of laser power on the microstructure and mechanical properties of Ti-50Ta alloy prepared by L-PBF

Additive manufacturing is a promising approach for fabricating β-titanium alloys for bone implant applications, among which Ti-Ta alloys have attracted extensive attention due to their excellent biocompatibility. However, current additive manufacturing of Ti-Ta alloys mostly uses mixed powders as feedstocks, which leads to a narrow processing window. To avoid this, in this study, Ti-50Ta (wt.%) samples with varied microstructures and mechanical properties were fabricated via Laser Powder Bed Fusion (L-PBF) using self-developed Ti-50Ta powder, by adjusting the laser power. Electron Backscatter Diffraction (EBSD) and Transmission Electron Microscopy (TEM) characterizations were performed to reveal the promoting effect of Ta on the equiaxation and the room-temperature deformation mechanisms of metastable β phase. The results show that Ti-50Ta-100W and Ti-50Ta-200W exhibit significant Transformation-Induced Plasticity (TRIP) and Twinning-Induced Plasticity (TWIP) behaviors during deformation. Specifically, the Ti-50Ta-200W achieves a tensile strength of 882 MPa with a total elongation of 25.6%. In contrast, the Ti-50Ta-300W, which contains thermal stress-induced lamellar ω phase and twins in the as-fabricated state, exhibits a higher tensile strength of 1131 MPa with a superior strength-to-modulus ratio, while maintaining a total elongation of 8.1%. This indicates that Ti-50Ta powders have excellent application potential as feedstocks for preparing bone implant materials via L-PBF.