Ti-Ta Alloys Research Articles

Electrochemical Characteristics of Osteoblast Cultured Ti-Ta Alloy for Dental Implant

Electrochemical behaviors of surface modified and MC3T3-E1 cell cultured Ti-30Ta alloys have been investigated using various electrochemical methods. The Ti alloys containing Ta were melted by using a vacuum furnace and then homogenized for 6 hrs at . MC3T3-E1 cell culture was performed with MC3T3-E1 mouse osteoblasts for 2 days. The microstructures and corrosion resistance were measured using FE-SEM, XRD, EIS and potentiodynamic test in artificial saliva solution at . Ti-Ta alloy showed the martensite structure of phase and micro-structure was changed from lamellar structure to needle-like structure as Ta content increased. Corrosion resistance increased as Ta content increased. Corrosion resistance of cell cultured Ti-Ta alloy increased predominantly in compared with non cell cultured Ti- Ta alloy due to inhibition of the dissolution of metal ion by covered cell. value of MC3T3-E1 cell cultured Ti-40 Ta alloy showed which was higher than those of other Ti alloy. Polarization resistance of cell-cultured Ti-Ta alloy increased in compared with non-cell cultured Ti alloy.

Changes in mechanical properties of Ti alloys in relation to alloying additions of Ta and Hf

Abstract The effects of Ta and Hf on the dynamic Young's moduli and tensile properties of Ti–Ta and Ti–Hf alloys for biomedical applications are comparatively studied in this paper. It is found that with increasing Hf content, the dynamic Young's modulus of the Ti–Hf alloy gently decreases and its tensile strength keeps on increasing. In contrast, with increasing Ta content, the dynamic Young's modulus of the Ti–Ta alloys first decreases, reaches a minimum value of 69 GPa and then increases. In parallel, the tensile strength first increases, reaches a maximum value of 587 MPa, and then slightly decreases. It is shown that the addition of Hf has a slight influence on the dynamic Young's modulus and a strong influence on the tensile properties of the Ti–Hf alloy, while an increase of Ta content has a strong effect on both the dynamic Young's modulus and tensile properties of the Ti–Ta alloy.

Influence of concentration and temperature on the corrosion behavior of titanium, titanium-20 and 40% tantalum alloys and tantalum in sulfuric acid solutions

Titanium (Ti) exhibits an excellent corrosion resistance in oxidizing acids and neutral media but it is severely attacked in reducing acids. On the contrary, tantalum (Ta) presents an excellent resistance in both oxidizing and reducing acids, but its high cost limits its use to very aggressive conditions. The Ti–Ta alloys are promising materials for replacing Ta, due to their lower cost and density when compared to Ta, and their expected higher corrosion resistance when compared to Ti. The corrosion behavior of Ti, Ti-20 and 40% Ta alloys and Ta in sulfuric acid (H 2SO 4) solutions at 25, 50 and 75 °C was studied using open-circuit potential measurements, potentiodynamic polarization and electrochemical impedance spectroscopy. Different corrosion behaviors (spontaneous passivation, spontaneous activation and cathodically induced activation) were observed depending on the Ta content, acid concentration and temperature. Increasing of Ta content and decreasing of both H 2SO 4 concentration and temperature led to an increase in corrosion resistance. A transition in corrosion behavior was observed between 20 and 40% Ta content: Ti and Ti–20Ta alloy presented similar corrosion behavior, whereas Ti–40Ta behaved like Ta. This is related to the nature of the respective oxide films formed on the four materials.

Transmission electron microscopy studies of microstructure of Ti–Nb and Ti–Ta alloys after ball milling and hot consolidation

Two Ti alloys with compositions Ti-10Ta and Ti-10Nb (at.%) were milled in a high-energy mill for a maximum of 80 h in an argon atmosphere. A nanocrystalline structure of alpha-Ti(X) (X = Ta or Nb) solid solution was formed in both investigated alloys after milling, as shown by X-ray diffraction. Transmission electron microscopy observations of powders milled for 80 h revealed chemical inhomogeneity of particles in nanometre-scale regions and an average crystallite size of about 10 nm. The pulse plasma sintering method was applied for hot consolidation of milled powders. The mean density of pulse plasma sintering compacts of Ti-Nb alloy was about 99.5% of the theoretical value, whereas the density of the Ti-10Ta sample was lower, close to 92% of the theoretical value. Transmission electron microscopy observation of compacted samples showed that the sintering process caused the formation of a two-phase alpha + beta structure in both investigated alloys, with a mean grain size of 220 nm. The chemical inhomogeneity and high degree of deformation in nanometre-scale regions of milled powders led to a martensitic transformation, resulting in formation of a 9R martensite structure.

Phase transformation and second phases in ternary Ni–Ti–Ta shape memory alloys

The phase transformation and microstructure in solution-treated Ni 50Ti 47Ta 3, Ni 50Ti 45Ta 5, Ni 49Ti 46Ta 5 shape memory alloys (SMAs) have been investigated. Two different second-phase particles, (Ti,Ta) 2Ni and a tantalum-rich solid solution (β-Ta) mostly located at grain boundaries are observed. These Ni–Ti–Ta alloys undergo a one stage B2 ↔ B19′transformation. Experimental results indicate that the Ta atoms are suggested to replace Ti atoms, instead of Ni atoms in these alloys. The transformation temperatures depression of Ni–Ti–Ta alloy is more than that of NiTi alloy under the same number of thermal cycles due to the presence of more second-phase particles. The above 4% deformation might induce plastic strain for the β-Ta. The Ni–Ti–Ta alloys exhibit a wide transformation hysteresis compared to NiTi binary alloys.

Corrosion resistance and biocompatibility of Ti–Ta alloys for biomedical applications

Corrosion resistance, wear resistance and biocompatibility of the studied Ti–Ta alloys with Ta contents of 10, 30 and 70 mass% together with the currently used metallic biomaterials pure titanium (Ti) and Ti–6Al–4V extra low interstitial (ELI) alloy were investigated for biomedical applications. Corrosion resistance was measured by an anodic polarization test using an automatic potentiostat in 5% HCl solution at 310K. Wear resistance was evaluated using a pin-on-disk type friction wear test system with a load of 4.9N at 310K in a simulated body fluid (Ringer's solution), and biocompatibility was judged by evaluating the cyto-toxicity through MTT assay. The passive behaviors are observed for all the studied Ti–Ta alloys, and the TiO2 passive films strengthened by the more stable Ta2O5 passive films result in improved corrosion resistance of the studied Ti–Ta alloys with increasing Ta content. All the studied Ti–Ta alloys are non-cytotoxic like pure Ti. The crystal structure shows little influence on the corrosion resistance and cyto-toxicity of the studied Ti–Ta alloys. The experimental results conform the expected excellent corrosion resistance and biocompatibility of the studied Ti–Ta alloys, which are better than or similar to those of pure Ti or Ti–6Al–4V ELI alloy used as standard biomaterials, suggesting their promising potential for biomedical applications.

Alloys that form conductive and passivating oxides for proton exchange membrane fuel cell bipolar plates

During the operation of proton exchange membrane (PEM) fuel cells, a high-resistance oxide is often formed on the cathode surface of base metal bipolar plates. Over time, this corrosion mechanism leads to a drop in fuel cell efficiency and potentially to complete failure. To address this problem, we have developed alloys capable of forming oxides that are both conductive and chemically stable under PEM fuel cell operating conditions. Five alloys of titanium with tantalum or niobium were investigated. The oxides were formed on the alloys by cyclic voltammetry in solutions mimicking the cathode- and anode-side environment of a PEM fuel cell. The oxides of all tested alloys had lower surface resistance than the oxide of pure titanium. We also investigated the chemical durability of Ti–Nb and Ti–Ta alloys in more concentrated solutions beyond those typically found in PEM fuel cells. The oxide films formed on Ti–Nb and Ti–Ta alloys remained conductive and chemically stable in these concentrated solutions. The stability of the oxide films was evaluated; Ti alloys having 3% Ta and Nb were identified as potential candidates for bipolar plate materials.

Effects of Ta content on Young’s modulus and tensile properties of binary Ti–Ta alloys for biomedical applications

Abstract The effects of Ta content on the microstructures, dynamic Young’s modulus and tensile properties of the quenched Ti–Ta alloys were investigated for biomedical applications. The microstructures were examined using a scanning electron microscopy (SEM) and an X-ray diffraction (XRD) analysis. The results indicate that the microstructures of the quenched binary Ti–Ta alloys are sensitive to Ta content. The Ti–Ta alloys exhibit lamellar HCP martensite (α′) structure at a Ta content below 20%, needle-like orthorhombic martensite (α″) structure at a Ta content between 30–50%, metastable β+α″ structure at a Ta content of 60%, and single metastable structure at a Ta content above 60%. The dynamic Young’s modulus and tensile properties of the binary Ti–Ta alloys depend strongly on Ta content. Ti–30% Ta and 70% Ta alloys have much lower modulus and a good combination of high strength and low modulus among all the studied Ti–Ta alloys. They have the great potential to become new candidates for biomedical applications.

Mechanical Properties of Binary Ti-Ta Alloys for Biomedical Applications

The effect of Ta content on the mechanical properties of the quenched binary TiTa alloys with different mass percentage of Ta from 10 to 80% was investigated in order to find a Ta content that gives a good balance of low modulus and high strength for biomedical applications. The mechanical properties of binary TiTa alloys depend strongly on the microstructures caused by Ta content. Among all the studied Ti–Ta alloys, Ti30 mass % Ta alloy with martensite ” and Ti70 mass % Ta alloy with metastable phase have the potential to be the new candidates for biomedical applications

Preparation and characterization of Ti–Ta alloys for application in corrosive media

Titanium (Ti) exhibits a good corrosion resistance in oxidizing acids and neutral media but is severely attacked in reducing acids. On the contrary, tantalum (Ta) presents an excellent resistance in both oxidizing and reducing acids, but its high cost limits its use to very aggressive conditions. The Ti–Ta alloys are promising materials for use in reducing acids, due to their lower cost and density when compared to tantalum, and their higher corrosion resistance when compared to titanium. Ti-20, 40, 60 and 80 wt.% Ta alloys were prepared by arc melting and were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometry (XRD). Some electrochemical experiments were performed in H 2SO 4 solutions at room temperature to evaluate their corrosion resistance.

OS7(2)-6(OS07W0195) Effect of Ta Content on Young's Modulus and Microstructures of Binary Ti-Ta Alloys

OS7(2)-6(OS07W0195) Effect of Ta Content on Young's Modulus and Microstructures of Binary Ti-Ta Alloys

OS07W0195 Effect of Ta content on young's modulus and microstructures of binary Ti-Ta alloys

OS07W0195 Effect of Ta content on young's modulus and microstructures of binary Ti-Ta alloys

Texture formation in Ti–Ta alloy disilicide thin films

Texture development in (Ti,Ta)Si2, formed from Ti–Ta alloy (0–6 at. % Ta) thin films sputtered on Si(001) and poly-Si substrates, was studied using both in situ and ex situ x-ray diffraction. The addition of Ta fundamentally changes the C54 texture. At 6 at. % Ta, an effective composition for lowering the C49–C54 transformation temperature, films on both substrates develop a strong (010) texture normal to the film plane. Alloy films on Si(001) also exhibit an in-plane orientational relationship between the final C54 texture and the underlying silicon lattice. A pseudoepitaxial film relationship with the substrate may, therefore, be playing an important role in the C54 transformation process. For 32 nm films on single-crystal substrates, the in situ measurements show that significant evolution of the C54 texture occurs during the growth process, suggesting that those grains well oriented with respect to the Si substrate lattice have higher growth velocities. The possibility of a template effect by the C40 or metal-rich Ti5Si3 phase is also discussed on the basis of texture considerations.

<I>In Vitro</I> Biocompatibility Studies of Fibroblast Cells on Ti-Ta Alloys

Medical science has enabled the substitution and reinforcement of body organs and tissue through the evolution of better materials. Metallic implants have been utilized to aid in injury wound healing as bone replacements, endoprosthesis, and percutaneous devices. Of concern with metallic devices is the prolonged effects and service life of the implant. It is known that metallic dissolution and premature failure can occur in the body leading to complications for the host. In an effort to provide more corrosion resistant materials with adequate strength for better resistance against high cycle fatigue, Ti–Ta alloys are presented to compete with current, popular materials such as Ti6Al4V. This research focuses on the binary alloy systems of Ti40Ta and Ti50Ta alloys for implant consideration. Three heat-treated versions of the Ti–Ta system that demonstrated high strength properties were also assessed. Cell culture testing of NIH-3T3 fibroblast cells was conducted to perform biocompatibility testing on these metal substrates. MTT cytotoxicity assays were performed to evaluate cellular behavior on the metal substrates. Flow cytometry assays were conducted to analyze rates of cell growth and cycling to determine best surface conditions among these metals. Results indicate very similar cellular activity on the Ti alloys and to a lesser degree on the commercially pure titanium and tantalum. Flow cytometry tests showed similar cellular growth rates on the different materials and on the control plastic. MTT assays indicate a higher degree of proliferation on the Ti–Ta alloys and on the Ti6Al4V. Although the Ti and Ta elemental materials supported slightly fewer cells on their surface, differences were minimal. Ti–Ta alloys appear to be comparable if not slightly more compatible than the standard Ti6Al4V.

The Effect of Ta Content on Phase Constitution and Aging Behavior of Ti-Ta Binary Alloys

Using Ti–Ta alloy to which Ta was added systematically, i.e. Ti–5 mass%Ta, 10 mass%Ta, 20 mass%Ta, 30 mass%Ta, 40 mass%Ta and 50 mass%Ta alloys, the effect of Ta concentration on phase constitution in the solution treated and quenched state and aging behavior is studied by electrical resistivity and Vickers hardness measurements and X-ray diffactometry. All alloys were solution treated at 1173 K for 3.6 ks and then quenched into ice water (STQ). STQed specimens were isochronally heat treated from 323 to 1173 K. STQed specimens of Ti–50 mass%Ta alloy were isothermally aging at five different temperatures, 573 K, 623 K, 673 K, 723 K and 773 K. In the solution treated and quenched state, only reflections of hexagonal martensite, α′ were obserevd by XRD in Ti–5Ta to 30Ta alloys, whereas only orthorhombic martensite, α′′, was identified by XRD in Ti–40Ta and 50Ta alloys. α′′ in Ti–50Ta alloy is reversely transformed into β upon isochronal heat treatment: the starting temperature is situated at a temperature between 623 K and 673 K. Isothermal aging of this alloy shows that α′′ directly decomposes to α and β phases without reverse transformation of α′′ at 573 K and 623 K aging. On isothermal aging above 673 K, α′′ reversely transforms into β and then isothermal ω phase precipitates in the reversed β.

Evaluation of mechanical and corrosion biocompatibility of TiTa alloys.

As-received and heat-treated Ti40Ta and Ti50Ta alloys were evaluated to determine their corrosion as well as mechanical performances and compared to Ti6A14V, a common material utilized for orthopedic (surgical) implants. Anodic potentiodynamic tests performed in Plasmalyte showed that all samples, except for the Ti50Ta specimen aged at 400 degrees C for 3 h gave a curve similar to that of Ti6A14V. Optical and TEM microscopy was performed to determine as-received and heat-treated microstructures. As-received materials showed an alpha precipitate in an alpha+beta and martensite matrix. Samples that were aged at 400 degrees C increased in the density and the length of the alpha precipitate. Vickers hardness measurements were performed to get an approximation of the tensile strengths. Aged Ti40Ta and Ti50Ta specimens produced the highest tensile values when compared to the Ti6A14V material, representing a 31% and 56% increase for the 3 h samples and an 18% and 58% increase for the 10 h samples. Of all the materials studied the Ti50Ta specimen aged for 10 h exhibited the best biocompatibility showing excellent corrosion resistance combined with the highest tensile strength (1089 MPa and 58% harder/stronger than Ti6A14V).

Short communication Effects of tantalum addition on transformation behaviour of (Ni51 Ti49 )1-x Tax and Ni50 Ti50-y Tay shape memory alloys

The effect of Ta content on the transformation characteristics of Ni–Ti–Ta ternary alloys has been studied. In (Ni51 Ti49 )1-x Tax type alloys, the phase transformation temperatures increase with Ta content, especially when the Ta content is less than 4 at.-%. In Ni50 Ti50-x Tax type alloys, the phase transformation temperatures decrease as Ta content increases. The martensite start temperature is less sensitive to changes in Ni content in ternary Ni–Ti–Ta alloys than that in Ni–Ti binary alloys. The phase transformation temperatures of Ni–Ti–Ta ternary alloys are mainly controlled by the Ni/Ti ratio in the Ni–Ti matrix.

Melting Method for Biomedical Ti-Ta Alloy with High Melting Point

Melting Method for Biomedical Ti-Ta Alloy with High Melting Point

Mechanisms for enhanced C54–TiSi2formation in Ti–Ta alloy films on single-crystal Si

The mechanisms are studied for enhanced formation of C54–TiSi2at about 700 °C when rapid thermal annealing at 3 °C/s in N2is performed on 32-nm-thick codeposited Ti–5.9 at.% Ta on Si(100) single-crystal substrates. The enhancement is related to an increased C54–TiSi2nucleation rate due to the development of a multilayered microstructure. The multilayer microstructure forms at temperatures below 600 °C with the formation of an amorphous disilicide adjacent to the Si substrate and a M5Si3(M = Ti, Ta) capping layer. This amorphous disilicide crystallizes at higher temperatures to C49–TiSi2. The multilayer microstructure introduces an additional interface that increases the area available for the heterogeneous nucleation of C54. The capping layer is identified as hexagonal Ti5Si3or its isomorphous compound (Ti1–xTax)5Si3. Crystal simulations demonstrate that C54(040) has a lattice mismatch of 6–7% relative to Ti5Si3(300) suggesting that a pseudomorphic epitaxial relationship may lower the interfacial energy between these two phases and reduce the energy barrier for C54 nucleation. A C40 disilicide phase was also observed at temperatures above that required to form C54–TiSi2suggesting that, in the present experiments, the C40 phase does not play a major role in catalyzing C54 formation.

Oxidation kinetics and mechanisms of Ti-Ta alloys

The oxidation kinetics of alloys containing nominally 5, 40, and 60 weight percent Ta, as well as pure Ti and Ta, were measured for 16 hr in argon-20% oxygen or pure oxygen at 800, 1000, 1200 and 1400°C. These three alloys were chosen as representative of low, intermediate and high-Ta content for comparison to previous studies. In addition to TGA, specimens were examined using scanning electron microscopy, electron microprobe, and X-ray diffraction. The effect of Ta on the oxidation of Ti is explained by an increase in the compositional range of the oxygen-stabilized α-phase while apparently reducing the solubility of oxygen and the diffusivity of Ti in both the α- and β-phases. The composition which exhibits the minimum oxidation rate varies depending on the temperature and atmosphere, but is governed by the solubility of Ta in oxygen-stabilized α-Ti.