Ti 13Nb 13Zr Alloy Research Articles

Effect of Solid Carburization on the Tribological Behaviors of Ti13Nb13Zr Alloy

Due to its high mechanical strength, exceptional biocompatibility, low elastic modulus, and superior corrosion resistance, Ti13Nb13Zr alloy is one of the potential candidates for implanted joints. However, the poor tribological property of Ti13Nb13Zr alloy has greatly limited its wide usage in artificial joints. The elevated temperature solid carburizing technology was used to improve tribological property of Ti13Nb13Zr alloy. It was found that the surface hardness of Ti13Nb13Zr alloy was increased to 812 HV after the carburization at 1523 K due to the formation of titanium carbide on the surface. With the increase in experimental temperature, the thickness of the carburized layer increased to 120 μm. In addition, the wear rate of Ti13Nb13Zr alloy decreased by 63.9% under serum lubrication condition after the carburization at 1473 K due to the formation of hard TiC on the surface of Ti13Nb13Zr.

Properties of composite oxide layers on the Ti13Nb13Zr alloy

ABSTRACTThe development of composite oxide layers on the Ti13Nb13Zr alloy, their structure and properties, were demonstrated. Two subsequent methods were applied to prepare the composite layers. During the first stage, gas oxidation produced a dense compact oxide layer, and subsequent oxide nanotubes were formed applied an electrochemical oxidation. The scanning electron microscopy, energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy, and Raman spectroscopy were used to examine the appearance, thickness, chemical and phase composition of the oxide layers. The results obtained revealed that the composite layers composed of two zones. The electrochemical formation of the outer nanotubular oxide zone occurred if the thickness of the first inner oxide zone was small enough because of resistance increasing with the inner zone thickness followed by a decrease in electrochemical reaction rate. The decreasing corrosion resistance of the Ti13Nb13Zr alloy was observed and explained by a model electric circuit.

Effect of dynamical chemical etching on the porous structure parameters of superelastic medical Ti–Nb–Zr alloy foam

A dynamical chemical etching technique under pressure is developed and used to fabricate sintered foams based on a superelastic Ti–Nb–Zr alloy. This technique is shown to effectively control the characteristics of a porous structure and to increase the porosity and the permeability of the material.

Production, structure and biocompatible properties of oxide nanotubes on Ti13Nb13Zr alloy for medical applications

This work deals with production and characterization of the oxide nanotubes on the biomedical Ti13Nb13Zr alloy. Anodic oxidation of this new type of vanadium-free titanium alloy was carried out in 1M ethylene glycol electrolyte with the addition of 4wt% NH4F under voltage-time conditions of 50V for 80min at room temperature. The results of FE-SEM, TEM, EDS, GIXD and XPS investigations confirmed the possibility of formation of the single-walled nanotubes on the bi-phase (α+β) alloy under study. An amorphous character of the obtained nanotubes was ascertained. The morphological parameters such as the length (~10μm), outer (362nm) and internal (218nm) diameter of the nanotube, were determined. The formed nanotubes were composed of oxides of the alloying elements derived from TiO2, Nb2O5, ZrO2, and ZrOx. Spontaneous passivation of the as-received Ti13Nb13Zr alloy in the normal saline solution at 37°C, was revealed by open-circuit potential measurements. The interface impedance of Ti13Nb13Zr electrode | oxide layer | normal saline solution, was determined by approximation of the experimental EIS data using the equivalent electrical circuit of modified Randle's cell. Potentiodynamic studies have shown no initiation of pitting corrosion up to 9.5V vs. SCE. The proposed surface modification method has been shown to eliminate the hemolysis of the alloy and to decrease slightly its corrosion resistance due to the porous structure of the formed nanotubes. These results give a new insight into improvement of the ability of the Ti13Nb13Zr implant alloy to osseointegration in a biological milieu.

Bactericidal activity of the Ti–13Nb–13Zr alloy against different species of bacteria related with implant infection

The Ti–6Al–4V alloy is one of the most commonly used in orthopedic surgery. Despite its advantages, there is an increasing need to use new titanium alloys with no toxic elements and improved biomechanical properties, such as Ti–13Nb–13Zr. Prosthetic joint infections (PJI) are mainly caused by Gram-positive bacteria; however, Gram-negative bacteria are a growing problem due to associated multidrug resistance. In this study, the bacterial adherence and viability on the Ti–13Nb–13Zr alloy have been compared to that of the Ti–6Al–4V alloy using 16 collection and clinical strains of bacterial species related to PJI: Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. When compared with the Ti–6Al–4V alloy, bacterial adherence on the Ti–13Nb–13Zr alloy was significantly higher in most staphylococcal and P. aeruginosa strains and lower for E. coli strains. The proportion of live bacteria was significantly lower for both Gram-negative species on the Ti–13Nb–13Zr alloy than on the Ti–6Al–4V alloy pointing to some bactericidal effect of the Ti–13Nb–13Zr alloy. This bactericidal effect appears to be a consequence of the formation of hydroxyl radicals, since this effect is neutralized when dimethylsulfoxide was added to both the saline solution and water used to wash the stain. The antibacterial effect of the Ti–13Nb–13Zr alloy against Gram-negative bacteria is an interesting property useful for the prevention of PJI caused by these bacteria on this potential alternative to the Ti–6Al–4V alloy for orthopedic surgery.

Influence of Substrate Temperature on Adhesion Strength of TiN Coating of Biomedical Ti–13Zr–13Nb Alloy

Adhesion strength between the coating and the substrate is considered as a significant factor, which may help determine both the successful implantation and the long-term stability of any coated implant. A weakly adhered coating on a medical implant may delaminate after the process of implantation, which in turn may severely limit the effectiveness along with the life of the implant itself. Related previous studies have shown that process parameters may have a direct influence on the quality of TiN coating. In the present work, the effect of substrate temperature on adhesion strength of TiN coating on Ti–13Zr–13Nb biomedical grade alloy was investigated. The coating parameter, which varied in this study, was the substrate temperature (i.e., 100, 200 and 300 ◦C). The adhesion strength of TiN coating was examined by means of scratch testing method. In addition, calibrated optical images were also used to verify the total coating failures on the scratched coated samples. Results indicated that an increase observed in the substrate temperature may have resulted in a decrease in the microdroplet form on TiN coating. In contrast, the adhesion strength of TiN coating was observed to equally increase when substrate temperature increased. It is believed that the higher mobility of atom at a higher substrate temperature (i.e., 300 ◦C) filling up the defect appears on the surface to provide a mechanical interlock and thus providing better adhesion strength.

Constitutive modeling and fracture behavior of a biomedical Ti–13Nb-13Zr alloy

The dynamic compression tests were performed at various strain rates (0.01, 1700, 2700 and 3500/s) and temperatures (25, 200, 400 and 600°C) for a biomedical Ti–13Nb-13Zr alloy. Based on experimental data, constitutive models were established using the Modified Johnson-Cook (J-C) model, Modified Khan–Huang–Liang (KHL) model and Artificial neural network (ANN) model, respectively. The new modified J-C model considers the coupled effects of strain hardening, strain rate hardening and thermal softening. In this work, a radial basis function artificial neural network (RBF-ANN) model was also developed to predict the high strain rate flow curves of Ti–13Nb-13Zr alloy. The results demonstrate that the flow behavior of Ti–13Nb-13Zr alloy is considerably influenced by the strain rate and temperature. The modified KHL model and ANN significantly enhance the predictability. The deformation behavior represented by dynamic recrystalization (DRX) and the instability flow has been discussed with reference to microstructural evolution during high strain rate compression. The validation of the developed constitutive model is embedded in the finite element analysis (FEA) to perform numerical simulations with ABAQUS/Standard to obtain the charpy impact energy.

Novel Electrochemical Test Bench for Evaluating the Functional Fatigue Life of Biomedical Alloys

The aim of the present work was first to develop and validate a test bench that simulates the in vitro conditions to which the biomedical implants will be actually subjected in vivo. For the preliminary application assessments, the strain-controlled fatigue tests of biomedically pure Ti and Ti–Nb–Zr alloy in simulated body fluid were undertaken. The in situ open-circuit potential measurements from the test bench demonstrated a strong dependence on the dynamic cycling and kind of material under testing. The results showed that during fatigue cycling, the passive oxide film formed on the surface of Ti–Nb–Zr alloy was more resistant to fatigue degradation when compared with pure Ti. The Ti–Nb–Zr alloy exhibited prolonged fatigue life when compared with pure Ti. The fractographic features of both materials were also characterized using scanning electron microscopy. The electrochemical results and the fractographic evidence confirmed that the prolonged functional fatigue life of the Ti–Nb–Zr alloy is apparently ascribable to the reversible martensitic phase transformation.

Electrochemical and biocompatibility examinations of high-pressure torsion processed titanium and Ti-13Nb-13Zr alloy.

The purpose of this study was to estimate the electrochemical behavior and biocompatibility of ultrafine-grained (UFG) commercially pure titanium (CPTi) and Ti-13Nb-13Zr (TNZ) alloy obtained by high-pressure torsion process. Electrochemical behavior of materials in artificial saliva at 37°C was evaluated by potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS), and the obtained results indicated that UFG TNZ alloy showed corrosion current density (jcorr =53 ± 5 nA cm-2 ) which was 2 times lower compared to coarse-grained (CG) TNZ alloy (jcorr =110 ± 12 nA cm-2 ) and higher corrosion resistance, while UFG CPTi and CPTi showed approximately the same corrosion rate (mean jcorr ∼ 38-40 nA cm-2 ). Static immersion test in artificial saliva, performed in this study, showed that the released ion concentrations from UFG materials were more than 10 times lower than the permitted concentration (the highest released Ti ion concentration from UFG CPTi and UFG TNZ alloy was 1.12 and 1.28 ppb, respectively, while permitted concentration was 15.5 ppb). The in vitro cytotoxicity tests, as the initial phase of the biocompatibility evaluation, showed that the fraction of surviving cells in all examined materials was much higher compared to the control sample and hence demonstrated absence of cytotoxicity and an increase of fibroblast cells adhesion on UFG materials surfaces. UFG CPTi and UFG TNZ alloy can be considered as promising materials for applications in dentistry due to high corrosion resistance and outstanding biocompatibility which were shown in this study. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1097-1107, 2018.

Effect of Al addition on superelastic properties of Ti–Zr–Nb-based alloys

The effects of Al addition on the superelastic properties of Ti–Zr–Nb alloys were investigated. Ti–18Zr–(12–16)Nb–(0–4)Al (at.%) alloys were prepared by the Ar arc melting method and superelastic properties, transformation temperature, and transformation strain were investigated quantitatively. The superelastic strain increased by the addition of Al and a large recovery strain of 6.1% was observed in a Ti–18Zr–13.5Nb–3Al alloy. The large superelastic strain of Al-added alloys was found to be due to a large transformation strain and a strong recrystallization texture.

Electrochemical Preparation of Porous Ti–13Zr–13Nb Alloy and It's Corrosion Behavior in Ringer's Solution

Electrochemical Preparation of Porous Ti–13Zr–13Nb Alloy and It's Corrosion Behavior in Ringer's Solution

Electrochemical Formation of Second Generation TiO2 Nanotubes on Ti13Nb13Zr Alloy for Biomedical Applications

The aim of this study was to obtain the second generation TiO2 nanotubes on the Ti13Nb13Zr alloy. Anodic oxidation of the alloy under study was carried out in 1 M (NH4)2SO4 electrolyte under voltage–time conditions of 20 V for 120 min. The morphological parameters of the obtained nanotubes of second generation such as the length (L), internal (Di) and outer (Do) diameter of nanotube were determined. It was found that the anodic oxidation of the Ti13Nb13Zr alloy conducted under proposed conditions allowed to obtain the single-walled nanotubes of the following geometrical parameters: the internal diameter 61 nm, outer diameter 103 nm, and the length 3.9 μm. The total surface area of the single-walled nanotubes was equal to 4.1 μm, and the specific surface area per cm (As) was estimated to be 15.6 cm/cm. Formation mechanism, structure and optimal morphological parameters of the obtained single-walled nanotubes on the Ti13Nb13Zr alloy have been discussed in detail.

Influence of ω phase precipitation on mechanical performance and corrosion resistance of Ti–Nb–Zr alloy

A recently investigated Ti–24at.% Nb–2at.% Zr alloy was cold-rolled with reductions of 75% and 95%, and the resulting materials were heat-treated under the same conditions. The two types of specimens obtained through this procedure show the same phase composition. Precipitation of an isothermal ω phase leads to some improvement in the properties of the 75%-rolled specimens. The 95%-rolled and subsequently heated specimens exhibit different performances compared to the 75%-rolled samples heated under the same processing conditions. The stress-induced martensitic transformation is inhibited in the 95%-rolled specimens, owing to the combined effects of the isothermal ω phase and texture. The Ti–24at.% Nb–2at.% Zr alloy shows open circuit potential and corrosion behavior similar to commercially pure Ti. The corrosion resistance of the alloy is reduced upon precipitation of the ω phase, owing to an unstable passive film.

The Determinants of Morphology and Properties of the Nanohydroxyapatite Coating Deposited on the Ti13Zr13Nb Alloy by Electrophoretic Technique

Abstract The titanium and its alloys belong at present to the most preferred and commonly applied biomaterials for load-bearing implants. The surfaces of biomaterials are subjected to modification, including the hydroxyapatite coatings deposited in order to ensure corrosion resistance and better joining between an implant and a bone through the possibility of ingrowth bone into the coating. In this paper, the morphology and properties of the nanohydroxyapatite coating deposited on the Ti13Zr13Nb flat surfaces using electrophoretic method are presented. Electrophoretic deposition at two different current values and two electrolytes (first – ethanol with nanoHAp, second – methanol with nanoHAp) was applied. The scanning electron microscopy examinations and wettability angle measurements showed an increase in the coating thickness, the surface coverage and decrease in biocompatibility with increasing voltage. The surface condition and biocompatibility of coatings were better when using methanol/nanoHAp solution as compared to the ethanol/nanoHAp one.

Study of low-modulus biomedical β Ti–Nb–Zr alloys based on single-crystal elastic constants modeling

CALPHAD-type modeling was used to describe the single-crystal elastic constants of the bcc solution phase in the ternary Ti–Nb–Zr system. The parameters in the model were evaluated based on the available experimental data and first-principle calculations. The composition-elastic properties of the full compositions were predicted and the results were in good agreement with the experimental data. It is found that the β phase can be divided into two regions which are separated by a critical dynamical stability composition line. The corresponding valence electron number per atom and the polycrystalline Young׳s modulus of the critical compositions are 4.04–4.17 and 30–40GPa respectively. Orientation dependencies of single-crystal Young׳s modulus show strong elastic anisotropy on the Ti-rich side. Alloys compositions with a Young׳s modulus along the <100> direction matching that of bone were found. The current results present an effective strategy for designing low modulus biomedical alloys using computational modeling.

Influence of polyetheretherketone coatings on the Ti–13Nb–13Zr titanium alloy's bio-tribological properties and corrosion resistance

Polyetheretherketone (PEEK) coatings of 70–90μm thick were electrophoretically deposited from a suspension of PEEK powder in ethanol on near-β Ti–13Nb–13Zr titanium alloy. In order to produce good quality coatings, the composition of the suspension (pH) and optimized deposition parameters (applied voltage and time) were experimentally selected. The as-deposited coatings exhibited the uniform distribution of PEEK powders on the substrate. The subsequent annealing at a temperature above the PEEK melting point enabled homogeneous, semi-crystalline coatings with spherulitic morphology to be produced. A micro-scratch test showed that the coatings exhibited very good adhesion to the titanium alloy substrate. Coating delamination was not observed even up to a maximal load of 30N. The PEEK coatings significantly improved the tribological properties of the Ti–13Nb–13Zr alloy. The coefficient of friction was reduced from 0.55 for an uncoated alloy to 0.40 and 0.12 for a coated alloy in a dry sliding and sliding in Ringer's solution, respectively. The PEEK coatings exhibited excellent wear resistance in both contact conditions. Their wear rate was more than 200 times smaller compared with the wear rate of the uncoated Ti–13Nb–13Zr alloy. The obtained results indicate that electrophoretically deposited PEEK coatings on the near-β titanium alloy exhibit very useful properties for their prospective tribological applications in medicine.

Electrochemical modification of Ti–13Nb–13Zr alloy surface in phosphate based solutions

Abstract The Ti–13Nb–13Zr alloy can successfully be used as a bone implant because it contains elements that are not harmful to the human body. However, to increase its osseointegration and corrosion resistance, this alloy is subjected to surface modifications. In this work, Ti–13Nb–13Zr alloy was modified by plasma electrolytic oxidation (PEO) in a 0.1 M NH 4 H 2 PO 4 solution with the addition of Ca 3 (PO 4 ) 2 powder (25 g/dm 3 ) under voltages of 150, 300 and 400 V. The morphology, cross-section, chemical composition, surface roughness and corrosion resistance of the coatings formed on the substrate by the PEO process are presented in this work. An increase in the applied voltage caused an increase in the number of pores and an increase in the amounts of calcium and phosphorus incorporated in the oxide layer. Analysis showed that all samples were covered by titanium oxide, which was present in the form of anatase. The results demonstrated that the surface modification of the Ti–13Nb–13Zr alloy through the PEO process improves its corrosion resistance.

Surface Characteristics of Nano-Structured Silicon/Hydroxyapatite Deposition onto the Ti-Nb-Zr Alloy.

The Ti-Nb-Zr alloy was manufactured with 35 wt% of Nb and 10 wt% of Zr by arc melting furnace to be a beta phase. Electrochemical deposition of Si substituted Ca/P was performed by pulsing the potential with a method of cyclic voltammetry, and changed cyclic time between 10, 30, 70, and 150. The electrolyte was prepared by dissolving the reagent-grade chemicals: Ca(NO3)2, NH4H2PO4, and Na2SiO3 x 9H20 to be 1.67 of Ca/P ratio and silicon contents were controlled to be 1 wt%. The surface characteristics were observed by field-emission scanning electron microscopy, X-ray diffractometer, and electrochemical corrosion as a potentiodynamic test. The Si substituted hydroxyapatite layer was successfully formed on the Ti-35Nb-10Zr alloy substrate by electrochemical deposition. A surface morphologies showed needle like shape at 10 cycles, then changed to be a circular with increment of cycles. The Ca/P ratio was the range between 1.5 and 2.0, the crystalline of hydroxyapatite could be confirmed. The corrosion behavior of Si-HA deposition was related with surface shape and thickness by increment, of cyclic times. Higher cyclic times of deposition had higher corrosion potential and current density than that of lower cyclic surface.

Influence of the Ageing Temperature on the Microstructure and Selected Mechanical Properties of Ti13Nb13Zr Alloy

Investigation results concerning changes occurring in the microstructure of the near β titanium alloy, grade: Ti13Nb13Zr, when the ageing temperature was changed within the range 350÷650°C, are presented in the paper. These changes were assessed on samples previously quenched in water from the selected soaking temperature in the single-phase β range (800°C). Microstructures were investigated by means of the optical microscopy and scanning electron microscopy (SEM). Phases occurring in the alloy at various ageing temperatures were identified with using the XRD analysis. Microstructure investigations were supplemented by hardness measurements by means of the Vickers apparatus, type HP0 250. In addition, for the selected ageing temperatures, the Charpy impact tests were performed on the Ti13Nb13Zr alloy samples. These tests were carried out on the Charpy tester of a potential energy of 150 J. The results of Charpy impact tests were supported by the fractographic documentation of samples fractures. The fractographic investigations were performed by means of the scanning electron microscope NovaNanoSEM 450.The obtained results constitute the valuable supplementation of the data bases concerning microstructures and mechanical properties of near β titanium alloys.

In situ X-ray diffraction study of athermal and isothermal omega-phase crystal lattice in Ti-Nb-based shape memory alloys

It is currently not still sufficiently clear whether “athermal” and “isothermal” ω-phases formed in Ti-based alloys are two different phases, or are indeed one phase, albeit with different formation mechanisms and kinetics. An X-ray diffraction study of a crystal structure of both athermal and isothermal ω-phases formed in a thermomechanically treated Ti–Nb–Zr alloy was conducted to clarify this situation. It was concluded that the ω-phase formed by two different kinetics: athermal, upon subzero cooling, and isothermal upon 300°C-ageing, possesses a unique crystal lattice structure with c/a=0.613±0.003, but differ in the intensity of the microstress relaxation phenomena accompanying their formation, which are more prominent in the latter than in the former.