Ti 13Nb 13Zr Alloy Research Articles

The role of heat treatment on microstructure and mechanical properties of Ti–13Zr–13Nb alloy for biomedical load bearing applications

The suitability of heat treated Ti–13Zr–13Nb (TZN) alloy for biomedical load bearing applications has been investigated. Depending upon the heat treatment conditions, the microstructure of TZN alloy mainly consists of α , β or α ” martensite phases. In general, for all the deformation and solution treatment temperatures the variation of the hardness and tensile strength with cooling rate is similar. The elastic modulus of TZN alloy decreases with an increase in cooling rate from the solution treatment temperature. Relatively fine α + β microstructure increases the hardness and tensile strength. The presence of martensite and/or retained β in the microstructure decreases the hardness and elastic modulus and increases the ductility substantially whereas higher amount of α phase in the matrix increases the elastic modulus. Decomposition of martensite and retained β into α phase during aging increases the hardness, elastic modulus and tensile strength and decreases the ductility. Among the samples studied, the aged TZN sample, which was deformed and solution treated at 800 °C followed by water quenching, is a promising candidate for the application as implant material.

Studies on plasma sprayed bi-layered ceramic coating on bio-medical Ti–13Nb–13Zr alloy

Biomedical Ti alloys are prone to undergo degradation due to the combined effect of wear and corrosion. To overcome these problems, surface modification techniques are being used. In this paper, the biomedical Ti alloy Ti–13Nb–13Zr was plasma sprayed with nanostructured Al2O3–13wt%TiO2, yttria stabilized zirconia powders and bilayer containing alternate layers of the two coatings to improve the corrosion resistance and microhardness of the substrate. The plasma sprayed coatings were characterized by X-ray diffraction, scanning electron microscopy and Raman spectroscopy. The microstructure, microhardness and surface roughness of the coatings were investigated. The corrosion resistance of the coatings was studied in simulated body conditions. The results show improved corrosion resistance for the bilayered coating compared to the individual plasma sprayed coatings on biomedical Ti–13Nb–13Zr alloy substrate.

Improved pre‐osteoblast response and mechanical compatibility of ultrafine‐grained Ti–13Nb–13Zr alloy

Metallic implantation materials having high yield strength, low elastic modulus, and non-cytotoxic alloying elements would be advantageous for the long-term stability of implants. This study assessed the surface and mechanical properties, and also in vitro osteoconductivity of ultrafine-grained (UFG) Ti-13Nb-13Zr alloy produced by dynamic globularization without any severe deformation for future biomedical applications as an endosseous implant material. The surface characteristics and mechanical properties were investigated by orientation image microscopy, contact angle measurements, optical profilometry, and uniaxial tension tests. Mouse calvaria-derived pre-osteoblastic cell (MC3T3-E1) attachment, spreading, viability, alkaline phosphatase (ALP) activity, and quantitative analysis of osteoblastic gene expression on UFG Ti-13Nb-13Zr alloy were compared with coarse-grained (CG) Ti-13Nb-13Zr and CG Ti-6Al-4V alloys. Dynamic globularized Ti-13Nb-13Zr alloy has an ultrafine grain size (0.3 μm) and an excellent combination of yield strength and elastic modulus compared with CG alloys, which displayed significantly lower water contact angles compared with CG alloys (P<0.05). The UFG and CG Ti-13Nb-13Zr alloys displayed significantly increased cellular attachment compared with CG Ti-6Al-4V alloy (P<0.05). The UFG Ti-13Nb-13Zr supported better cell spreading and more numerous focal adhesions. ALP activity (P<0.05) and mRNA expressions of the osteoblast transcription factor genes (osterix, Runx2) and marker gene for osteoblast differentiation (osteocalcin) were markedly increased in cells grown on the UFG substrate compared with CG substrates at early incubation timepoints. Enhanced pre-osteoblast response to UFG Ti-13Nb-13Zr substrate is attributable to the non-cytotoxic alloying elements and the submicron scale grain size contributes to the superior surface hydrophilicity and abundant grain boundaries favorable for cell behavior. These findings indicate that dynamic globularized UFG Ti-13Nb-13Zr alloy is promising for load-bearing endosseous implant material because of excellent mechanical and biological compatibilites.

Wear and corrosion behaviour of Ti–13Nb–13Zr and Ti–6Al–4V alloys in simulated physiological solution

Wear and corrosion behaviour of cold-rolled Ti–13Nb–13Zr alloy, with martensitic microstructure, and Ti–6Al–4V ELI alloy, in martensitic and two-phase (α + β) microstructural conditions, was studied in a Ringer’s solution. The wear experiments were performed at room temperature with a normal load of 40 N and sliding speeds 0.26, 0.5 and 1.0 m/s. The corrosion behaviour was studied at 37 °C using open circuit potential-time measurements and potentiodynamic polarization. It was found that Ti–13Nb–13Zr alloy has a substantially lower wear resistance than Ti–6Al–4V ELI alloy in both microstructural conditions. Surface damage extent increases with sliding speed increase and is always smallest for martensitic Ti–6Al–4V ELI alloy with highest hardness. Both alloys exhibit spontaneous passivity in Ringer’s solution. Corrosion potential values are similar for all three materials. However, Ti–13Nb–13Zr and martensitic Ti–6Al–4V ELI alloys show improved corrosion resistance comparatively to Ti–6Al–4V ELI alloy with (α + β) microstructure. Martensitic Ti–6Al–4V ELI alloy possesses the best combination of both corrosion and wear resistance, although its corrosion resistance is found to be slightly higher than that of the Ti–13Nb–13Zr alloy.

Enhanced Photoassisted Water Electrolysis Using Vertically Oriented Anodically Fabricated Ti−Nb−Zr−O Mixed Oxide Nanotube Arrays

Self-ordered, highly oriented arrays of titanium-niobium-zirconium mixed oxide nanotube films were fabricated by the anodization of Ti(35)Nb(5)Zr alloy in aqueous and formamide electrolytes containing NH(4)F at room temperature. The nanostructure topology was found to depend on the nature of the electrolyte and the applied voltage. Our results demonstrate the possibility to grow mixed oxide nanotube array films possessing several-micrometer-thick layers by a simple and straightforward electrochemical route. The fabricated Ti-Nb-Zr-O nanotubes showed a ∼17.5% increase in the photoelectrochemical water oxidation efficiency as compared to that measured for pure TiO(2) nanotubes under UV illumination (100 mW/cm(2), 320-400 nm, 1 M KOH). This enhancement could be related to a combination of the effect of the thin wall of the fabricated Ti-Nb-Zr-O nanotubes (10 ± 2 nm) and the formation of Zr oxide and Nb oxide layers on the nanotube surface, which seems to slow down the electron-hole recombination in a way similar to that reported for Grätzel solar cells.

Production of Ti–13Nb–13Zr alloy for surgical implants by powder metallurgy

The Ti–13Nb–13Zr near-β alloy was developed aiming the replacement of the traditional Ti–6Al–4V alloy in surgical implants owing to its larger biocompatibility. Samples of this alloy were obtained using the blended elemental technique from hydrided powders. The isochronal sintering of the compacts for 2 h was carried out in the range 900–1,400 °C with a heating rate of 20 °C min−1. In this work, the behavior of the elementary powders during sintering and the corresponding microstructural evolution were investigated. The alloy was characterized by means of scanning electron microscopy (SEM) in the backscattered mode, X-ray diffraction, and density measurements. The results indicate that the homogenization of the alloy is diffusion-controlled. With increasing temperature, homogenization of the alloy takes place and a fine plate-like α + β structure is found throughout the microstructure in temperatures above 1,300 °C. The process variables were defined aiming to minimize interstitial pick-up (C, O, and N) and avoiding intensive grain growth.

Enhanced mechanical compatibility of submicrocrystalline Ti–13Nb–13Zr alloy

This study aimed to achieve enhanced mechanical compatibility of Ti–13Nb–13Zr alloy by producing submicrocrystalline microstructure without imposing severe strains. In order to find the optimum processing conditions, a series of compression tests was performed for initial martensite microstructure in strain ranges up to 0.8 and 1.4, the strain rate range of 10−3 to 1s−1 and the temperature range of 500–700°C. Based on the microstructural analysis, the submicrocrystalline (∼0.4μm) alloy consisting of high-angle grain boundaries was produced via dynamic globularization at temperature of 600°C, equivalent strain rate of 10−1s−1 and strain of 1.4, which showed about 25% enhanced mechanical compatibility as compared to the conventionally produced ones. The formation of submicrocrystalline microstructure at relatively low strain was investigated by examining the microstructure before and after dynamic globularization.

Biomimetic Modification of Porous TiNbZr Alloy Scaffold for Bone Tissue Engineering

Porous titanium (Ti) and Ti alloys are important scaffold materials for bone tissue engineering. In the present study, a new type of porous Ti alloy scaffold with biocompatible alloying elements, that is, niobium (Nb) and zirconium (Zr), was prepared by a space-holder sintering method. This porous TiNbZr scaffold with a porosity of 69% exhibits a mechanical strength of 67 MPa and an elastic modulus of 3.9 GPa, resembling the mechanical properties of cortical bone. To improve the osteoconductivity, a calcium phosphate (Ca/P) coating was applied to the surface of the scaffold using a biomimetic method. The biocompatibility of the porous TiNbZr alloy scaffold before and after the biomimetic modification was assessed using the SaOS2 osteoblast-like cells. Cell culture results indicated that the porous TiNbZr scaffold is more favorable for cell adhesion and proliferation than its solid counterpart. By applying a Ca/P coating, the cell proliferation rate on the Ca/P-coated scaffold was significantly improved. The results suggest that high-strength porous TiNbZr scaffolds with an appropriate osteoconductive coating could be potentially used for bone tissue engineering application.

Studies on the corrosion and wear behavior of the laser nitrided biomedical titanium and its alloys

The effects of laser nitriding on surface hardness, corrosion and wear behavior of the conventional biomedical implants such as commercially available pure titanium and Ti–13Nb–13Zr alloy is reported. The influence of alloying elements such as Zr and Nb on nitride formation was also studied by nitriding the newly developed alloy (Ti–13Nb–13Zr). The surface modified samples were characterized using optical microscope (OM), Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) techniques. Corrosion rate, wear rate and coefficient of friction were made under simulated body condition for commercially available pure titanium and Ti–13Nb–13Zr alloy. The high speed processing of these alloys enabled smooth and crack free surface.

Preparation of bone-like apatite coating on surface of Ti-25Nb-2Zr alloy by biomimetic growth method

A bone-like apatite layer consisting of nano-crystals of apatite phase was prepared on the surface of Ti-25Nb-2Zr alloy by chemical biomimetic growth method. TiNbZr alloy specimens were first oxidized at 500 °C for 2 h in the air. Then, they were immersed in 40 °C saturated Na2HPO4 solution for 15 h and 25 °C saturated Ca(OH)2 solution for 8 h in turn for pre-calcification. The pre-calcified specimens were immersed in modified simulated body fluid up to 15 d for biomimetic growth. After common oxidization, amorphous titania and anatase were detected on the specimen surface. Except for the substantial amount of calcium and phosphorus, no new phase appeared on the pre-calcified specimens. After the coating process, it was found that the (002) orientation was the preferred orientation during the growing period of hydroxyapatite. The inorganic composition and structure of the coating are very similar to those of human thigh bone, which will be advantageous for its application as biomedical material.

Influence of Zr content on phase transformation, microstructure and mechanical properties of Ti 75− xNb 25Zr x ( x = 0–6) alloys

Ternary Ti–Nb–Zr alloys consisting of biocompatible alloying elements have been prepared to investigate the effect of Zr content on β → α phase transformation, microstructure and mechanical properties. The study showed that element Zr stablized the β phase and that its effect on β phase transus exhibited a “margin effect”. With increasing Zr content, the microstructure of the Ti–Nb–Zr alloy was refined and the strength of ternary Ti–Nb–Zr alloys was also improved while the plasity significantly decreased. The Ti 72Nb 25Zr 3 alloy exhibited the maximum ultimate tensile strengh of 775 MPa and Ti 73Nb 25Zr 2 exhibited the lowest elastic modulus of 62 GPa. The low elastic modulus of Ti 73Nb 25Zr 2 was attributed to the formation of stress-induced martensite (α″ phase).

Characterization of Microstructure and Mechanical Properties of TiNbZr Alloy during Heat Treatment

TiNbZr alloy was prepared by vacuum consumable arc melting furnace. The effects of solution and aging heat treatment on the microstructure and mechanical properties of this alloy were studied. The results show that ultimate tensile strength over 1000 MPa can be obtained when the alloy is solutioned for 1 h and then aged at 300 and 350 °C. α phase precipitation appears under the condition of the treatment of solution for 1 h, followed by aging at 400 °C and 450 °C. The aging time plays an important part in α phase precipitation. The ultimate tensile strength increases to 850 MPa and the elongation keeps around 11% when the alloy is aged at 400 °C for 9 h.

Porous TiNbZr alloy scaffolds for biomedical applications

In the present study, porous Ti–10Nb–10Zr alloy scaffolds with different porosities were successfully fabricated by a “space-holder” sintering method. By the addition of biocompatible alloying elements the porous TiNbZr scaffolds achieved significantly higher strength than unalloyed Ti scaffolds of the same porosity. In particular, the porous TiNbZr alloy with 59% porosity exhibited an elastic modulus and plateau stress of 5.6 GPa and 137 MPa, respectively. The porous alloys exhibited excellent ductility during compression tests and the deformation mechanism is mainly governed by bending and buckling of the struts. Cell cultures revealed that SaOS2 osteoblast-like cells grew on the surface and inside the pores and showed good spreading. Cell viability for the porous scaffold was three times higher than the solid counterpart. The present study has demonstrated that the porous TiNbZr alloy scaffolds are promising scaffold biomaterials for bone tissue engineering by virtue of their appropriate mechanical properties, highly porous structure and excellent biocompatibility.

Nanotubular oxide layer formation on Ti–13Nb–13Zr alloy as a function of applied potential

Nanotubular oxide layer formation on biomedical grade α + β type Ti–13Nb–13Zr alloy was investigated using anodization technique as a function of applied dc potential (10–40 V) and anodizing time (30–180 min) in 1 M H3PO4 + 0.5 wt% NaF at room temperature. The as-formed and crystallized nanotubes were characterized using SEM, XRD, and TEM. There was a bimodal size distribution of nanotubes with diameters at the range of 25–110 nm. Nanotubes nucleated on β matrix exhibited uniform surface appearance with circular morphology, whereas those nucleated on α phase yielded parabolic shape. TEM/EDS analysis detected the three component elements of the alloy in the nanotube. Heat treatment significantly altered the distinct interface between the nanotubes and the barrier oxide layer.

Electrochemical corrosion behaviour of nanotubular Ti–13Nb–13Zr alloy in Ringer’s solution

Nanotubular oxide layer formation was achieved on biomedical grade Ti–13Nb–13Zr alloy using anodization technique in 1 M H 3PO 4 + 0.5 wt.% NaF. The as-formed and heat treated nanotubes were characterized using SEM, XRD and TEM. Corrosion behaviour of the nanotubular alloy was investigated employing potentiodynamic and potentiostatic polarization. The alloy after nanotubular oxide layer formation exhibited significantly higher corrosion current density than the bare alloy. The lower corrosion resistance of the nanotubular alloy was suggested to be associated with the distinctly separated barrier oxide/concave shaped tube bottom interface. A heat treatment at 150 °C appreciably enhanced the corrosion resistance property.

Microstructure and Mechanical Properties of TiNbZr Alloy during Cold Drawing

Abstract The cold workability of solution-treated TiNbZr biomedical β titanium alloy was investigated. TiNbZr alloy was fabricated by vacuum consumable arc melting furnace. Cold drawing was carried out for further deformation of the studied alloy. During cold drawing, the alloy exhibited excellent workability. Deformation twins appeared when the reduction of cold deformation was around 20%. Dislocations slipping contributed much to plastic deformation in further drawing. The ultimate tensile strength will go up to 1170 MPa and the elongation is larger than 10% when the reduction reaches 80%. Small grains ranging from 20 nm to 50 nm can be obtained when the reduction is 80%.

Effect of different annealing on the anelastic relaxation in Ti–13Nb–13Zr alloy

Measurements of anelastic relaxation (internal friction and frequency) as a function of temperature were carried out in Ti–13Nb–13Zr samples using Flexural Vibration of the first tone of samples in an Acoustic Elastometer System (Vibran Technology ®) operating in the kHz bandwidth. The samples were analyzed under two different conditions: (a) heat treated at 1170 K for 30 min and water-quenched (β-solution treated, β-ST WQ) and (b) this alloy β-ST WQ was submitted to one subsequent aging for 3 h at 670 K (β-ST WQ + 670 K/3 h). Experimental spectra of anelastic relaxation were determined in the temperature range from 300 K to 500 K for a heating rate of 1 K/min under a pressure of 10 −5 Torr. The results show a relaxation structure strongly dependent on the microstructure of the material. The dynamic elastic modulus ( E) of Ti–13Nb–13Zr alloy can be determined by flexural vibrations through frequency ( f) measurements ( f ∝ E 1/2). The anelastic relaxation spectrum of Ti–13Nb–13Zr alloy as a function of temperature obtained does not reveal the presence of interstitial solutes in solid solution, in the temperature range of measurements.

Solute segregation and its influence on the microstructure and electrochemical behavior of Ti–Nb–Zr alloys

The main aim of this work is to evaluate microstructure and electrochemical behavior of Ti–30Nb– xZr alloys using polarization techniques. Several alloys with different Zr contents were evaluated (from 2.5 to 15 wt.%). Samples were prepared by arc melting and cast in copper molds in a centrifugal casting machine. The as-cast samples showed a dendritic microstructure whose scale was found to depend on the Zr content. Martensite formation proved to be dependent on solute segregation. It was observed that the addition of Zr has no influence on corrosion potential. However, Zr addition affects the passive current density behavior. After polarization, the microstructures with passive film formed on their surfaces were analyzed by scanning electron microscopy.

Corrosion behavior of Ti–13Nb–13Zr alloy used as a biomaterial

Titanium alloys were developed as an alternative to stainless steels and have been extensively used as biomaterials ever since. One of these alloys is Ti–13Nb–13Zr (TNZ), a near-beta phase alloy containing elements with excellent biocompatibility. The main advantage of the TNZ alloy, compared to other titanium alloys, such as Ti–6Al–4V and Ti–6Al–7Nb, widely used as biomaterials, is its low elasticity modulus, closer to that of bone, and the absence of aluminum and vanadium, which have been reported to cause long-term adverse effects. In this paper, the corrosion and electrochemical behavior of TNZ alloy (as cast and after oxygen charge) was studied in a PBS solution. The results showed that, with the oxygen load, there is a significant reduction of the anodic current in almost the whole potential spam explored in this work, meaning that the corrosion rate decreases when the doping is performed.

Nanocomposite hydroxyapatite formation on a Ti–13Nb–13Zr alloy exposed in a MEM cell culture medium and the effect of H 2O 2 addition

Titanium alloys are known to nucleate an apatite layer when in contact with simulated body fluid. This improves the bioactivity of titanium implants and accelerates osseointegration. Promoting the formation of hydroxyapatite on biocompatible metals is, therefore, a very important topic of biomaterials research. In this paper, the formation of hydroxyapatite (HA) on the near-β Ti–13Nb–13Zr alloy by immersion in minimal essential medium (MEM), with and without H 2O 2 addition, has been studied using electrochemicals methods, scanning electron microscopy and X-ray photoelectron spectroscopy. The in vitro biocompatibility of this alloy was evaluated by cytotoxicity tests. The Ti–13Nb–13Zr alloy exhibits passive behaviour over a wide potential range in MEM and the passive film is composed of an inner barrier layer and an outer porous layer. The addition of H 2O 2 leads to a thickening of the outer porous layer and strongly reduced current density. With regard to the surface composition, immersion in MEM solution results in the formation of an island-like distribution of HA + amino acids. Addition of H 2O 2 to the MEM solution strongly promotes the formation of a thicker, continuous but porous nanocomposite layer of HA + amino acids. The Ti–13Nb–13Zr alloy is non-toxic and the nanocomposite HA + amino acid layer formed in the MEM solution favours the growth of osteoblast cells. For Ti alloys, the release of H 2O 2 in the anti-inflammatory response appears to be an important beneficial process as it accelerates osseointegration.