Research Projects

Titanium (Ti)-based alloys with high specific strength have garnered immense attention in the biomedical applications owing to its good biocompatibility. Ti also offers good mechanical response, a property much sought for biological stents used to rectify spinal disorders. Elastic modulus is one of the primary mechanical properties which needs to be near that of the human bone of 30-40 GPa. Low elastic modulus is often exhibited by the β-phase of Ti-alloys along with the superior response on corrosion resistance when compared with (α + β)-based alloys. β-phase is not the stable phase at room temperature, and therefore, β-stabilizers are often added. However, the currently used Ti-6Al-4V implant alloy needs to be phased out because of reduced cell viability induced with the interaction of harmful Al and V ions with the body constituents [1-3]. Among many β stabilizers, Mo and Nb are the two potential alloying elements exhibiting the ability to possess adequate mechanical strength and to reduce the elastic modulus of the β-Ti alloy. They also can release minimum number of ions in the body. Composition range examined with the alloying of Mo, especially, is limited to 20 wt.% [4]. This further necessitates examining the role of wider compositional field of Mo with the synergistic alloying of Nb. Stents targeted for the spinal surgery must be durable enough to minimize the revised surgery since such surgeries are extremely delicate. Pt is used as a stent for delicate spinal disorders. Although Pt is biocompatible, highly durable, beneficial for the oxidative stress related treatments, has lower thermal expansion coefficient; it becomes quite expensive, when used as a base stent material [5]. Therefore, one of the aims of this proposed research is to explore the role of Pt as an alloying element in β-Ti(Mo, Nb) for potential spinal stent alloys. Biocompatibility of β-Ti is also attributed to its good corrosion resistance in the environment of human body constituents owing to the formation of titania oxide on the surface of these implants [3, 6]. Formation of titania often involves diffusion of elements out of the bioimplants, which otherwise, results in the deterioration of mechanical properties with depletion of the elements. To help minimizing the diffusion of the elements out of the implants, a Ti-55 at.% Cu coating is applied on the implant, which further promotes antibacterial properties and osteointegration [6, 7]. Hence, along with the search on new Ti-based alloys preferably with low elastic modulus, dedicated research is also underway to come up with a coating alloy which can develop smaller interaction zone with the implant and thinner but adherent titania oxide. Therefore, a high-throughput diffusion multiple approach will be implemented in the proposed research to help designing novel Pt-modified β-Ti(Mo, Nb) implant alloy integrated with the determination of composition-dependent elastic moduli, diffusional and oxidation properties.

Diffusion, elastic modulus, oxidation, titanium, phase kinetics, microstructure.