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.

钛（Ti）及其合金是极具应用前景的金属生物医用材料。然而，当前临床使用的钛及钛合金难以同时满足高强度、高延伸率以及低弹性模量的使用需求。金属基复合材料可通过定制化微观结构实现优异的力学性能，该优势源于其微观结构的可调控性。本研究设计并制备了一种新型Ti-30（质量分数，wt.%）Nb金属-金属复合材料。采用放电等离子烧结（Spark plasma sintering, SPS）结合热轧与退火工艺完成该Ti-30Nb复合材料的制备。退火态复合材料的微观结构由纤维状富钛区、扩散过渡区以及富铌区共同组成，使其具备优异的综合力学性能。其抗拉强度与延伸率分别高达724 MPa与11%，而复合材料的弹性模量仅为52 GPa。该材料的高强度主要源于富钛区的固溶强化以及扩散过渡区的细晶强化；而优异的延伸率则可归因于扩散过渡区与富铌区所发挥的裂纹阻滞效应。