Unveiling the microstructure-property relationships of additively manufactured Ti-Ta bimetal composites

Abstract

Ti-based composites with excellent multiple properties are highly required for surgical implant applications. Herein, we developed the Ti-Ta bimetal composites by the Electron Beam Powder Bed Fusion (EB-PBF) with the regulation of the scanning speed of the electron beam. It can be found that the metallurgical interface bonding can be formed between the Ti matrix and residual Ta particles in the Ti-Ta bimetal composites, and the application of the highest scanning speed of the electron beam (0.700 m/s) facilitates the achievement of the higher yield strength but slightly lower ductility than the other two composites fabricated under the lower scanning speed of electron beam. The strength enhancement of the Ti-Ta bimetal composites mainly derives from grain refinement and solid solution strengthening, and the contribution of load transfer strengthening, dislocation strengthening, and Orowan strengthening also takes roles to some extent. The higher ductility of the composites fabricated with lower scanning speed of the electron beam (0.600 m/s and 0.675 m/s) mostly derives from the stronger interfacial bonding between residual Ta particles and Ti matrix and lower dislocation density in the interfacial area. In addition, compared to Ti-6Al-4V, the Ti-Ta bimetal composites have comparable wear resistance and better corrosion resistance, and in vitro biocompatibility. The findings pave the new route for developing the Ti-based composites with the desired multiple properties for surgical implants.