A novel Ti-30Nb metal-metal composite: Microstructural evolution and mechanical behavior

Titanium (Ti) and its alloys are the most attractive metallic biomedical materials. However, the currently used Ti and Ti alloys can hardly meet the requirements on high strength and elongation as well as low modulus. The metal-based composites usually show good mechanical properties, owing to the feasibility to obtain tailored microstructures. A novel Ti-30 (wt. %) Nb metal-metal composite was designed and fabricated in the present work. Spark plasma sintering (SPS) followed by hot rolling and annealing was applied to fabricate the Ti-30Nb composite. The microstructure of the as-annealed composite shows a combination of fiber-like Ti-enriched zones, diffusion zones and Nb-enriched zones, leading to good comprehensive mechanical properties. The tensile strength and elongation are as high as 724 MPa and 11 %, respectively, while the elastic modulus of the composite is only 52 GPa. The high strength is mainly attributed to the solid strengthening in Ti-enriched zones and grain refinement strengthening in diffusion zones. While, the good elongation may be attributed to the crack-blockings in the diffusion zones and Nb-enriched zones.