Ti-Ta Alloys Research Articles

Surface modification of TiTa alloy by hydrothermal-precalcification treatment and its excellent apatite-forming inductivity

TiTa alloys are ideal candidate materials for biomedical implants due to their good biocompatibility and low elastic modulus. However, the poor surface bioactivity affects their clinical efficacy. In this work, a facile two-step hydrothermal-precalcification route was employed to boost the bioactivity of TiTa alloy. A super-hydrophilic Ta-containing TiO2 film with hierarchical micro/nanostructure was first constructed on the surface of the TiTa alloy via hydrothermal treatment. After the subsequent precalcification treatment, calcium and phosphorus species with low content were introduced into the film without morphological changes. The simulated body fluid (SBF) soaking tests demonstrated that the induction formation time of bone-like apatite was greatly reduced from 18 days to only 1 day for TiTa alloy with two-step surface treatment. The results suggest that the hydrothermal-precalcification treatment is a promising approach for improving the osteoinductive activity of titanium-based implant materials.

Investigation of impact load and erosion behaviors on Ti-Ta alloy surface through the synergistic effect of ultrasonic cavitation and micro-abrasive particles

Ti–Ta alloy micro-nano surface processing is crucial for achieving biocompatibility. To investigate the cavitation and micro-abrasive particle damage characteristics, and the deformation mechanism of Ti–Ta alloy material surface, indentation theory, and the J-C constitutive model were adopted. Numerical load prediction models for ultrasonic cavitation and micro-abrasive particles' impact on Ti–Ta alloy surfaces were developed, and the erosion behaviors of ultrasonic cavitation and micro-abrasive particles’ impact on Ti–Ta alloy surfaces individually and in synergy were experimentally investigated. The inversion analysis shows that the range of ultrasonic cavitation impact load is 0.025–1.015 N, and there are material peeling and interconnection phenomena in the cavitation erosion pit. On the other hand, the impact load range of 10 μm spherical smooth SiO2 micro-abrasive particles is 0.107–0.814 N, and there is no material peeling or interconnection phenomenon in the micro-abrasive particle erosion pit. Additionally, the cavitation erosion rate is determined through changes in roughness and depression volume, resulting in a rate of 38.6%. In contrast, the cavitation-induced micro-abrasive particle erosion rate reached 166.4%. The results show that the impact load and erosion rate of ultrasonic cavitation-induced micro-abrasive particles are greater than those of cavitation impact load and erosion rate. Furthermore, ultrasonic cavitation-induced micro-abrasive particles impact is found to be more conducive to achieving micro-nano processing of Ti–Ta alloy surface.

Surface Characterization of 5M NaOH Treated Ti-Ta Alloys Exposed to Simulated Body Fluid.

Surface Characterization of 5M NaOH Treated Ti-Ta Alloys Exposed to Simulated Body Fluid.

Design, Preparation, and Mechanical Property Investigation of Ti–Ta 3D‐Auxetic Structure by Laser Powder Bed Fusion

In recent years, Ti–Ta alloy has become a hot material in orthopedic implants. At the same time, the metal lattice structure with a negative Poisson's ratio has a great prospect in the application of implants due to its unique mechanical properties. Herein, an antichiral three‐dimensional polyhedron (A3P) lattice structure with negative Poisson's ratio is designed. This lattice structure is prepared by laser powder bed fusion (LPBF) technology using Ti–Ta alloy as the feedstock material. The surface morphology and relative density of the Ti–Ta samples built with different laser scanning speeds are compared for the optimization of the Ti–Ta's LPBF parameter. Then, the A3P structure of the Ti–Ta alloy is fabricated using the optimized LPBF parameters. The negative Poisson's ratio effect of the A3P structure is verified by finite element analysis (FEA) and compared with experimental results. The compression test results show that the yield strength and elastic modulus of the A3P structure are 9.2 MPa and 0.14 GPa, respectively, which is suitable for the orthopedics application. A3P structure has higher fracture energy compared with diamond structure, indicating it can absorb more energy in the fracture process. A3P shows a promising prospect in the application of orthopedics implantation.

Improving mechanical properties and antibacterial response of α/β ternary Ti–Ta alloy foams for biomedical uses

This study investigates the potential of Ti–Ta–Sn alloys for biomedical applications due to their excellent mechanical properties and biocompatibility, with a particular focus on their use in trabecular bone replacement. This work aims to analyze the influence that of Sn has on the mechanical properties and antibacterial response of α−β ternary Ti–13Ta–xSn (x:3, 6, 9, and 12 at.%) alloy foams. The Ti-based alloys were designed considering three aspects; (i) final microstructure, (ii) alloying element types, and (iii) thermodynamics while using MAAT and ThermoCalc software. The alloys were obtained by mechanical alloying, with used milling times being 30 h for Ti–13Ta–3Sn, 10 h for Ti–13Ta–6Sn, 10 h for Ti–13Ta–9Sn, and 15 h for Ti–13Ta–12Sn. The foams were obtained using NaCl as the space holder (50 v/v% porosity) and consolidated by a hot pressing method at 780 °C for 30 min, applying a load of 40 MPa. Both the Staphylococcus aureus ATCC 6538 strain and Escherichia coli ATCC 8739 strain were used to evaluate the antibacterial responses of Ti-based alloy foams. The Ti-based alloy foams were composed mostly by a mix of α and β-phases. The metallic foams exhibited relative homogeneous pore distribution with a size between 100 and 450 μm and having an average porosity slightly higher than 50%. The samples showed elastic modulus values between 1 and 2 GPa, compressive yield strengths over 150 MPa, and microhardness over 450 HV. All Ti-based alloy foams showed no antibacterial activity nor bacterial adhesion, indicating that there is bacterial adhesion inhibition.

Investigation on the Microstructure and Mechanical Properties of the Ti-Ta Alloy with Unmelted Ta Particles by Laser Powder Bed Fusion

Titanium-tantalum (Ti-Ta) alloy has excellent biomechanical properties with high strength and low Young's modulus, showing great application potential in the biomedical industry. In this study, Ti-Ta alloy samples were prepared by laser powder bed fusion (LPBF) technology with mixed pure 75 wt.% Ti and 25 wt.% Ta powders as the feedstock. The maximum relative density of Ti-Ta samples prepared by LPBF reached 99.9%. It is well-accepted that four nonequilibrium phases, namely, α', α″ and metastable β phase exist in Ti-Ta alloys. The structure of α', α″ and β are hexagonal close-packed (HCP), base-centered orthorhombic (BCO) and body-centered cubic (BCC), respectively. X-ray Diffraction (XRD) analysis showed that the α' phase transformed to the α″ phase with the increase of energy density. The lamellar α'/α″ phases and the α″ twins were generated in the prior β phase. The microstructure and mechanical properties of the Ti-Ta alloy were optimized with different LPBF processing parameters. The samples prepared by LPBF energy density of 381 J/mm3 had a favorable ultimate strength (UTS) of 1076 ± 2 MPa and yield strength of 795 ± 16 MPa. The samples prepared by LPBF energy density of 76 had excellent ductility, with an elongation of 31% at fracture.

Microstructure and Mechanical Characteristics of Ti-Ta Alloys before and after NaOH Treatment and Their Behavior in Simulated Body Fluid

In the present study, the microstructure and mechanical properties of Ti-xTa (x = 5%, 15%, and 25% wt. Ta) alloys produced by using an induced furnace by the cold crucible levitation fusion technique were investigated and compared. The microstructure was examined by scanning electron microscopy and X-ray diffraction. The alloys present a microstructure characterized by the α' lamellar structure in a matrix of the transformed β phase. From the bulk materials, the samples for the tensile tests were prepared and based on the results and the elastic modulus was calculated by deducting the lowest values for the Ti-25Ta alloy. Moreover, a surface alkali treatment functionalization was performed using 10 M NaOH. The microstructure of the new developed films on the surface of the Ti-xTa alloys was investigated by scanning electron microscopy and the chemical analysis revealed the formation of sodium titanate and sodium tantanate along with titanium and tantalum oxides. Using low loads, the Vickers hardness test revealed increased hardness values for the alkali-treated samples. After exposure to simulated body fluid, phosphorus and calcium were identified on the surface of the new developed film, indicating the development of apatite. The corrosion resistance was evaluated by open cell potential measurements in simulated body fluid before and after NaOH treatment. The tests were performed at 22 °C as well as at 40 °C, simulating fever. The results show that the Ta content has a detrimental effect on the investigated alloys' microstructure, hardness, elastic modulus, and corrosion behavior.

Directional transport and coalescence behavior on Titanium-Tantalum alloy surface: Insights from experiment and molecular dynamics simulation

Friction and wear of artificial joints are severe problems. By designing a structure for directional transporting lubricant onto the Ti-Ta alloy surface, the friction or wear can be effectively reduced. Herein, molecular dynamics (MD) simulation and experiment were employed to study the directional transport and coalescence behavior of droplets on wedge-shape structure Ti-5Ta (wt%) alloy surface. Results show that water droplets can be continuously transported. Moreover, the experimental results of static and dynamic contact angle measurement show that the experiment agrees well with the MD simulation. Finally, the anti-gravity directional transport was achieved on a tilting Ti-5Ta (wt%) alloy surface. This work provides insights for reducing friction and extending service life of artificial joints in the medical field.

Strengthening mechanism of lamellar-structured Ti–Ta alloys prepared by powder metallurgy

Titanium-tantalum alloys with lamellar microstructure were fabricated by cold isostatic pressing under 400 MPa and pressure-free sintering at 1600 °C. By such a low-cost powder metallurgy method, the Ti–Ta alloy exhibited the tensile yield strength of 1124 MPa at room temperature, which was twice that of the cast Ti–Ta alloys. The microstructure and mechanical properties were characterized in detail to elucidate the deformation behavior and the strengthening mechanism of the Ti–Ta alloys prepared by powder metallurgy. With the increasing Ta content, the width of the α laths decreased, and that of the β laths increased, leading to the precipitation of the acicular α in the β laths. Correspondingly, the yield and ultimate strength increased, while the strain to failure decreased. Lamellar structure strengthening was determined to be the dominating mechanism for the high strength of the Ti–Ta alloys prepared by powder metallurgy. After quantitatively evaluating the contributions of laths, solute atoms, prior β grain boundaries, and dislocations, a model was established to illustrate the yield strength of the Ti–Ta alloys. The calculated values agreed well with the measured strength values of the Ti–Ta alloys, indicating that this model is effective in forecasting the strength of the dual-phase Ti alloys with lamellar structure.

Structure of Ti-Ta Alloys Fabricated by Electron-beam Surface Alloying

In the present study, Ta coatings with a thickness of 1.7 and 4.2 μm were deposited on Ti samples through reactive magnetron sputtering. The coatings are furthermore treated by a scanning electron beam in order to form the Ti-Ta surface alloy. A change in the phase composition of the Ti-Ta alloy was observed through X-ray diffraction (XRD). The microstructure and the chemical composition of the samples were studied via scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX). The results indicate that in both cases the thickness of the alloyed zone remains the same at about 50 μm. The concentration of Ta in the alloyed zone increases with the increase in thickness of the pre-applied coating. The sample with the 1.7 μm Ta coating has a single-phase hexagonal closed packed structure, corresponding to the \(\alpha \) phase, whilst the sample with the 4.2 μm coating exhibits a biphasic hexagonal closed-packed structure and a body-centred cubic structure, corresponding to \(\alpha '\) martensitic and β phases.

Surface Modification of Ti–30Ta Alloy by Deposition of P(VDF-TrFE)/BaTiO3 Coating for Biomedical Applications

This study aims to promote an adequate methodology for coating an experimental Ti-30Ta alloy with P(VDF-TrFE)/BaTiO3. The combination of a copolymer with a ceramic has not been used until now. Ti-30Ta is an excellent choice to replace current alloys in the global market. The composite deposition on the Ti-30Ta substrate was performed by a spray coating process and at low temperature using two different surface modifications: surface acidic etching and surface polishing. Characterization was divided into four areas: (I) the substrate surface treatments used and their influences on the adhesion process were evaluated using surface energy, wettability, and roughness analyses; (II) the properties of the composite film, which were carried out using X-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG), and differential scanning calorimetry (DSC); (III) the study of the adhesion of the film on the substrate, which was performed by a scratch test; (IV) the final product, which was evaluated to determine the surface properties after the coating process. Biofilm formation using Staphylococcus aureus and Staphylococcus epidermidis strains and a hemocompatibility test were performed as biological assays. The results indicated that the P(VDF-TrFE)/BaTiO3 film showed high thermal stability (up to ≈450 °C); the FTIR and DSC tests indicated the presence of the β phase, which means that the material presents a piezoelectric nature; and the scratch test showed that the samples with the polish treatment provided a better adhesion of the film with an adhesion strength of ~10 MPa. From the SEM analysis, it was possible to determine that the spray deposition coating process resulted in a well-applied film as evidenced by its homogeneity. Microbiological tests showed that for Staphylococcus aureus, the bacterial growth in the coated Ti-30Ta presented no significant differences when compared to the alloy without coating. However, for Staphylococcus epidermidis, there was considerable growth on the coated Ti-30Ta, when compared to the non-coated alloy, indicating that the film surface may have favored bacterial growth. The hemolysis assay showed that the coated material presents hemocompatible characteristics when in contact with blood cells. The results obtained indicate that the Ti-30Ta alloy coated with P(VDF-TrFE)/BaTiO3 is a promising alternative for implant applications, due to its biocompatible properties, simplicity, and low cost.

Structural, mechanical and electrochemical properties of spark plasma sintered Ti-30Ta alloys

Ti-Ta alloys are choice materials for bio-medical applications, but obtaining tailormade material properties through using spark plasma sintering (SPS) fabrication exhibits potential challenges. The effects of sintering temperature, pressure and holding time on the microstructural, crystallographic, mechanical and corrosion behaviour of spark plasma sintered Ti-30Ta alloys were investigated. Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffractometry, microhardness and instrumented nanoindentation were used for the investigation. Microstructures obtained include martensite plates (alpha-Ti phases), beta-Ti phases, as well as significant volume of beta-Ta phases. Notable variation in crystal structure, mechanical properties and electrochemical behaviour were recorded. Generally, the materials exhibited high densification (>98%), improved micro-and nano-indentation hardness (>500 Hv), and elastic moduli (>40 GPa). Average Oxygen content of the sintered samples was 0.0106%. The measured properties of the sintered Ti-30Ta alloys suggest they can be efficient for applications in biomedical technologies.

Ti–Ta dental alloys and a way to improve gingival aesthethic in contact with the implant

The development of Ti-based alloys with improved properties for medical applications is a challenge nowadays in the field of materials engineering. In this study, the color of oxide layers developed by anodic oxidation in H2SO4 solution on Ti–Ta alloys was studied and the alteration in microhardness was evaluated. The alloys were manufactured by levitation fusion technique using Ti as base material and Ta was added in 5, 15, 25, and 30 wt%. After the alloys were passivated, changes of oxide color function of applied potential, the growth of oxide mass and the microhardness were investigated. The studies showed that the oxide mass increases with the potential and the hardness values vary as a function of Ta addition. The microhardness results showed that the oxide layer developed after passivation on the surface of Ti–25Ta alloy exhibited higher hardness values and a denser oxide layer as compared to the Ti–5Ta, Ti–15Ta, and Ti–30Ta alloys. Using a potential of 70 V a redish oxide color was obtained which might have optimal aplications in dentistry due to its aesthetics and mechanical properties.

Effect of heat treatment on microstructure and mechanical properties of Ti30Ta alloy for biomedical applications

Effect of heat treatment on microstructure and mechanical properties of Ti30Ta alloy for biomedical applications

EIS Characterization of Ti Alloys in Relation to Alloying Additions of Ta.

The increased popularity of Ti and its alloys as important biomaterials is driven by their low modulus, greater biocompatibility, and better corrosion resistance in comparison to traditional biomaterials, such as stainless steel and Co–Cr alloys. Ti alloys are successfully used in severe stress situations, such as Ti–6Al–4V, but this alloy is related to long-term health problems and, in response, different Ti alloys composed of non-toxic and non-allergic elements such as Nb, Zr, Mo, and Ta have been developed for biomedical applications. In this context, binary alloys of titanium and tantalum have been developed and are predicted to be potential products for medical purposes. More than this, today, novel biocompatible alloys such as high entropy alloys with Ti and Ta are considered for biomedical applications and therefore it is necessary to clarify the influence of tantalum on the behavior of the alloy. In this study, various Ti–xTa alloys (with x = 5, 15, 25, and 30) were characterized using different techniques. High-resolution maps of the materials’ surfaces were generated by scanning tunneling microscopy (STM), and atom distribution maps were obtained by energy dispersive X-ray spectroscopy (EDS). A thorough output of chemical composition, and hence the crystallographic structure of the alloys, was identified by X-ray diffraction (XRD). Additionally, the electrochemical behavior of these Ti–Ta alloys was investigated by EIS in simulated body fluid at different potentials. The passive layer resistance increases with the potential due to the formation of the passive layer of TiO2 and Ta2O5 and then decreases due to the dissolution processes through the passive film. Within the Ti–xTa alloys, Ti–25Ta demonstrates excellent passive layer and corrosion resistance properties, so it seems to be a promising product for metallic medical devices.

Evaluations of microstructure and fatigue properties of Ti-Ta alloys

In recent years, the demand for implants has increased in the orthopedic field due to the aging of the population. Among them, Ti-6Al-4V alloy is very often used. However, its high Young's modulus and cytotoxicity are regarded as problems. Therefore, we are focusing on titanium and tantalum, which are highly corrosion-resistant elements, and are developing Ti-Ta alloy, which is a β-type titanium alloy that exhibits low Young's modulus and low cytotoxicity. Furthermore, from the viewpoint of safety and durability, both high strength and low elasticity and excellent fatigue characteristics are required. In this study, we identified the microstructure and crystal structure of 4-types of heat-treated Ti-Ta alloys. In addition, torsional fatigue and plane bending fatigue tests were performed. By comparing these results, we investigated the relationship between structure and fatigue characteristics. From SEM and TEM observation, EBSD and EDS results, it was found that Tantaulum was dissolved in the β-Ti matrix in any heat treatment conditions. Furthermore, α-Ti was deposited at the grain boundaries by 500℃ aging. It was also found that the average crystal grain size increased due to the increase in the solution temperature and the aging treatment. Then, the torsional fatigue characteristics improved as the crystal grain size became smaller. The plane bending fatigue characteristics were improved by strengthening precipitation with α-Ti.

Investigation on sintering processes and mechanical properties of Ti–Ta alloys by molecular dynamics simulation.

The aim of this work was to introduce an EAM potential function to describe the sintering kinetics of Ti–Ta alloys by molecular dynamics simulation to understanding the dynamics behavior during the Ti–Ta alloys sintering process. The potential energy and Lindemann index during heating were calculated and the evolution of local crystal structure, during heating was characterized. The results showed that the size of Ti and Ta nanoparticles had a great significant impact on the melting point of Ti–5Ta (wt%) alloys. To further verify the suitability of the EAM potential function in determining Ti–Ta alloys mechanical properties, the elastic modulus of Ti–5Ta (wt%) alloys was determined both experimentally and by molecular dynamics simulation. The experimental measurements and simulation calculations were in good agreement with each other, demonstrating the accuracy of the EAM potential function. This work provides ideas and guidance for further improving the potential applications of Ti–Ta alloys.

Finnis–Sinclair-type potential for atomistic simulation of defects behaviour in V-Ti-Ta ternary system

• Interatomic potential for V-Ti-Ta ternary system based on F-S formalism has been developed. • The Ti potential well reproduce the point-defect properties of vacancy and self-interstitial atoms and the pressure-volume relation. • The typical defect energies of solute atoms Ti and Ta in the V matrix and Ti and V in the Ta matrix predicted by the present potential were in good agreement with DFT results. Vanadium (V)-based alloys are potential candidates for structural materials of fusion reactors because of their excellent properties; recently, the V–Ti–Ta alloy has received considerable attention. The irradiation-resistant performance is significant for the development and application of fusion reactor materials. In this study, combining with our previously developed potentials of V and Ta, we developed the V-Ti-Ta interatomic potential based on the Finnis–Sinclair (FS) formalism, which is an important step towards an atomic-scale investigation of V-based alloys. The potential parameters were determined by fitting to a large database of experimental data and density functional theory (DFT) calculations. The formation energies of vacancy and self-interstitial atoms, as well as the pressure-volume relation obtained from the present Ti potential, were well reproduced. The typical defect energies of solute atoms Ti and Ta in the V matrix and Ti and V in the Ta matrix, such as the formation energies of substitutional solute atoms, binding energies between solute atoms and point defects, agree well with DFT results. Thus, the developed potentials are expected to be suitable for atomistic simulations of point defects evolution in the V-Ti-Ta ternary system.

A mechanical comparison of alpha and beta phase biomedical TiTa lattice structures

Recent orthopaedic implant alloy design has focused on β-type Ti alloys, as the body centred cubic (BCC) crystal structure has the tendency to be characterised by a low elastic modulus. Nevertheless, the currently most used metal is Ti-6Al-4V, which mainly retains a hexagonal closed packed (HCP) crystal structure when produced by additive manufacturing. The benefits and disadvantages of the mechanical response of each crystal structure for implant applications is yet to be explored. Utilising the TiTa alloy system, low modulus Ti25Ta and Ti65Ta lattices were additively manufactured with opposing crystal structures of α′ martensite (HCP) and β grains (BCC). The lattices showed similar tensile, compressive and high cycle fatigue behaviour, indicating that the α' alloy was mechanically equal to the β alloy for implant applications. The mechanical properties of both the TiTa lattices were also superior to identically manufactured lattices in Ti-6Al-4V in both as-built and heat treated conditions.

3D printing of a titanium-tantalum Gyroid scaffold with superb elastic admissible strain, bioactivity and in-situ bone regeneration capability

The simultaneous achievement of admirable mechanical compatibility and osteoinduction in metallic implants can avoid stress shielding and facilitate osseointegration and osteogenesis. Herein, we reported a titanium-tantalum (Ti-Ta) Gyroid scaffold in-situ fabricated with selective laser melting (SLM), a powder-bed-fusion three-dimensional (3D) printing process, enabling superb elastic admissible strain (EAS), bioactivity and in-situ bone regeneration capability. The printed scaffold with 90% porosity exhibited a good combination of low elastic modulus (1.8 GPa) and high compressive yield strength (55.5 MPa), resulting in a superb EAS (3.03%) that is suitable for the reconstruction of cancellous bone. The mechanisms of the high EAS were ascribed to the formation of β(Ti, Ta) solid solution, ultrafine β grains accompanying with nanocrystalline α' grains, and the existence of dislocations and stacking faults. Bone-like apatite was spontaneously induced on the surface of the printed Ti-Ta alloy due to the generation of self-passivating Ta2O5 film, indicating a good biomineralization ability. Compared to pure Ti, the printed Ti-Ta alloy exhibited enhanced expression of vinculin, earlier cell extension, increased nuclei density, better cell proliferation, and the up-regulated expression of osteogenesis genes. Animal studies further validated that the printed Ti-Ta scaffold was capable to reinforce bone integration and accelerate bone regeneration. These findings provided a promising strategy for treating bone defects through 3D printing of metallic scaffolds.