Ti-29Nb-13Ta-4.6Zr Research Articles

Investigations on achievable surface quality in milling of Ti-35Nb-7Zr-5Ta alloy

ABSTRACT β-type Titanium (Ti) alloy possesses less Young’s Modulus (E), which is significant for manufacturing of medical implants, since it reduces stress shielding effect. In this work, surface quality analysis on Ti-35Nb-7Zr-5Ta(TNZT) alloy was carried out to reveal the osseointegration characteristics. TNZT alloy was fabricated by vacuum arc melting followed by homogenization process. Microstructure analysis with X-ray diffraction spectroscopy study revealed the formulation of body-centered cubic structure in the TNZT alloy. Further high speed milling was carried out to analyze the impact of process variables on surface quality. Parameters include axial depth of cut (ap), cutting velocity (vc), and feed/tooth (fz) are taken into consideration. In general, implants are miniature in size; hence, Carbide flat end mill cutter size of 2 mm is used for investigation. 27 slots are generated under mist cooling condition by using factorial experimental design approach. Surface characteristics and morphology of machined region were examined to discover biocompatibility. It is observed that ‘ap’ and ‘vc’ significantly affect surface quality and lowest Ra of 0.422 µm was observed. It is well within the allowable value between 1 and 1.5 µm for better osseointegration. It is also revealed that microparticle deposition and groove formation intensifies when ‘ap’ is higher at 200 µm.

New Ti–35Nb–7Zr–5Ta Alloy Manufacturing by Electron Beam Melting for Medical Application Followed by High Current Pulsed Electron Beam Treatment

High-current pulsed electron-beam (PEB) treatment was applied as a surface finishing procedure for Ti–35Nb–7Zr–5Ta (TNZT) alloy produced by electron beam melting (EBM). According to the XRD results the TNZT alloy samples before and after the PEB treatment have shown mainly the single body-centered cubic (bcc) β-phase microstructures. The crystallite size, dislocation density, and microstrain remain unchanged after the PEB treatment. The investigation of the texture coefficient at the different grazing angle revealed the evolution of the crystallite orientations at the re-melted zone formed at the top of the bulk samples after the PEB treatment. The top-view SEM micrographs of the TNZT samples treated by PEB exhibited the bcc β-phase grains with an average size of ~85 μm. TEM analysis of as-manufactured TNZT alloy revealed the presence of the equiaxed β-grains with the fine dispersion of nanocrystalline α and NbTi4 phases together with β-Ti twins. Meanwhile, the β phase regions free of α phase precipitation are observed in the microstructure after the PEB irradiation. Nanoindentation tests revealed that the surface mechanical properties of the melted zone were slightly improved. However, the elastic modulus and microhardness in the heat-affected zone and the deeper regions of the sample were not changed after the treatment. Moreover, the TNZT alloy in the bulk region manufactured by EBM displayed no significant change in the corrosion resistance after the PEB treatment. Hence, it can be concluded that the PEB irradiation is a viable approach to improve the surface topography of EBM-manufactured TNZT alloy, while the most important mechanical parameters remain unchanged.

Comparison of Functionally Graded Hip Stem Implants with Various Second-Generation Titanium Alloys

Total hip Arthroplasty (THA) is performed every year at a very high frequency to improve the quality of life of thousands of patients all over the globe. Nevertheless, the expected service life of such surgery remains unsuitable for patients under 50 years old. This is mainly related to stress shielding and the potential adverse tissue reaction to some of the elements of the market-dominant implant materials. In this research, functionally graded (FG) implant designs of several titanium alloys layered with hydroxyapatite (HA) are proposed to provide lower implant stiffness compared to a solid stem to approach the requirements of human bone. Moreover, TNZT (Ti35Nb7Zr5Ta), and TMZF (Ti12Mo6Zr2Fe) second-generation titanium alloys are studied as a replacement for the famous Ti6Al4V alloy to avoid the adverse tissue reactions related to aluminum and vanadium elements. The different FG models are numerically tested using a 3D finite element simulation after virtual implantation in a femur bone under the dynamic load of a patient descending stairs. In the numerical study, the variation in stress distribution and strain energy in a femur bone is assessed for different FG hip stems as well as the axial stiffness of the hip stems. Results indicated an increase in strain energy and von Mises stress in the cortical and cancellous bones using FG hip stems. Additionally, the axial stiffness is reduced for all FG hip stems relative to the commercial Ti6Al4V hip stem.

Bone Tissue Engineering: Production of TNTZ Alloy by Powder Metallurgy

The demand for metallic biomaterials has increased proportionally to the number of elderly population and people who have bone disorders related to diseases, accidents, or premature wear. Because of this, the studies related to the development of metal alloys for applications in biomaterials have increased and Ti-29Nb-13Ta-4.6Zr (TNTZ) alloy received a great highlight. TNTZ alloy was obtained by powder metallurgy technique in order to study the microstructural development and investigate the interactions with in vivo environment. To perform this work, elementary powders were mixed in alloy stoichiometry, uniaxial and isostatically cold compacted and sintered in high vacuum (10-5 Torr) at temperatures from 800 °C up to 1600 °C. X-ray diffractometry showed a tendency for phase stabilization at higher temperatures. The density and microhardness tests showed increasing results as the temperature increased, showing values of 5.7 g/cm³ and 352 HV. The mechanical tests presented modulus of elasticity around 40 GPa, maximum compressive strength of 1018 MPa and flexural strength of 1297 MPa. The biological tests of Ti-29Nb-13Ta-4.6Zr samples sintered at 1600 °C demonstrated antimicrobial activity against Candida albicans and Pseudomonas aeruginosa, reducing 36 and 60 % and high in vivo biocompatibility, which supports their use in implants.

High-Surface-Energy Nanostructured Surface on Low-Modulus Beta Titanium Alloy for Orthopedic Implant Applications

Nanostructured surfaces represent pertinent material technologies to improve the biocompatibility aspects of orthopedic implant surfaces. The present work reports the development of nanostructured titania surface on a low-modulus TNZT (Ti-35Nb-7Zr-5Ta) beta titanium alloy. The major focus is to gain more insights into the wettability, surface energy and corrosion resistance of the developed nanostructures. The developed nanomorphologies have been found to be nanopetal-like structures with nanotopographies and composed predominantly of anatase phase. Wettability studies revealed a highly hydrophilic surface with a concurrent enhancement in surface energy (68% increment in polar surface energy) advantageous for improved osseointegration. The developed layer has demonstrated comparable corrosion resistance with untreated surface. By incorporating the multiple aspects of low-modulus TNZT alloy, hydrophilic titania surface with elevated surface free energy and comparable corrosion resistance, the present work opens prospective avenues for effective biomaterial surface design paradigms.

Hydroxyapatite coating on titanium alloy TNTZ for increasing osseointegration and reducing inflammatory response in vivo on Rattus norvegicus Wistar rats

Hydroxyapatite (HA) coating has been carried out on a titanium alloy Ti–29Nb–13Ta-4.6Zr (TNTZ) to improve the biocompatibility and bioactivity of the alloy in order to attain a high degree of osseointegration and low inflammatory reactions in bone tissue after implantation in orthopedic implant applications. The coating process was carried out using the electrophoretic deposition (EPD) method. TNTZ implants with and without HA coating were installed in the tibia of the Rattus norvegicus Wistar test rats; the test animals were then terminated after two weeks. The degree of osseointegration was measured using a removal torque tester, the Tumor Necrosis Factor-Alpha (TNF-α) level was measured by using the Enzyme-Linked Immunosorbent Assay (ELISA) method, and a histopathological analysis was carried out on the implanted tissue. TNTZ implants with HA coating exhibit significantly higher osseointegration compared to those without HA coating, whereas TNTZ implants without HA coating can trigger significantly higher TNF-α levels. Greater osteogenesis occurs in a bone tissue fitted with TNTZ implants with HA layers. The HA coating on the surface of the TNTZ implant can reduce excessive inflammation, enhance the osteogenesis process, and then improve osseointegration in the bone tissues of test animals. It is also expected to be suitable for orthopedic implant applications.

Experimental investigation into nano-finishing of β-TNTZ alloy using magnetorheological fluid magnetic abrasive finishing process for orthopedic applications

This study describes the effect of magnetorheological fluid assisted magnetic abrasive finishing (MRAF) process on the surface topography of fine finished high strength biomedical grade β-phase Ti–Nb–Ta–Zr (β-TNTZ) alloy for orthopedic applications. β-type Ti–35Nb–7Ta–5Zr alloy exhibit high strength, better corrosion resistance and excellent bioactivity in comparison with Ti–6Al–4V alloy. The topographic features of finished surfaces (including surface roughness, skewness, and kurtosis), percentage change in surface roughness, and material removal have been studied to understand the influence of MRAF processing parameters, such as carbonyl iron particles proportion, diamond abrasive particles proportion, rotational speed of the abrasive tool, and work gap between workpiece and abrasive tool. Furthermore, MRAF finishing has been conducted using raster and spiral strategies. The topographic characteristics of the finished surfaces have been measured using a noncontact three-dimensional Surface Profilometer and atomic force microscopy. The results of the study showed that all the input process parameters have strongly influenced the surface characteristics in both quantitative (material removal) and qualitative measures (Surface roughness). The β-TNTZ have possed excellent bio-mechanical properties such as high compressive strength (1195 MPa), micro-hardness (515 HV), corrosion resistance, and excellent bioactivity. The best optimal condition to obtain lowest SR (9 nm) and highest MR (65 mg) was obtained in the case of rater path finishing strategy at CIP – 40%vol., Dv – 3.5%vol., Nt – 900 rpm, and Gp – 1 mm. The maximum percentage change in surface roughness (%ΔRa) was measured around 97.68% and 93.27% in raster and spiral path strategy, respectively. The minimum surface finish ranging about 9 nm has been achieved through the MRAF process. Further, the raster path strategy has been found more effective in producing negative skewness (Ssk), kurtosis (Sku) value less than 3, and minimum number of peaks density (Spd). The overall results of the study suggested that MRAF of β-TNTZ alloy is a good solution for obtaining fine-finished orthopedic devices while sustaining their tribological and wear properties.

Evaluation of mechanical properties, in vitro corrosion resistance and biocompatibility of Gum Metal in the context of implant applications

In recent decades, several novel Ti alloys have been developed in order to produce improved alternatives to the conventional alloys used in the biomedical industry such as commercially pure titanium or dual phase (alpha and beta) Ti alloys. Gum Metal with the non-toxic composition Ti–36Nb–2Ta–3Zr–0.3O (wt. %) is a relatively new alloy which belongs to the group of metastable beta Ti alloys. In this work, Gum Metal has been assessed in terms of its mechanical properties, corrosion resistance and cell culture response. The performance of Gum Metal was contrasted with that of Ti–6Al–4V ELI (extra-low interstitial) which is commonly used as a material for implants. The advantageous mechanical characteristics of Gum Metal, e.g. a relatively low Young's modulus (below 70 GPa), high strength (over 1000 MPa) and a large range of reversible deformation, that are important in the context of potential implant applications, were confirmed. Moreover, the results of short- and long-term electrochemical characterization of Gum Metal showed high corrosion resistance in Ringer's solution with varied pH. The corrosion resistance of Gum Metal was best in a weak acid environment. Potentiodynamic polarization studies revealed that Gum Metal is significantly less susceptible to pitting corrosion compared to Ti–6Al–4V ELI. The oxide layer on the Gum Metal surface was stable up to 8.5 V. Prior to cell culture, the surface conditions of the samples, such as nanohardness, roughness and chemical composition, were analyzed. Evaluation of the in vitro biocompatibility of the alloys was performed by cell attachment and spreading analysis after incubation for 48 h. Increased in vitro MC3T3-E1 osteoblast viability and proliferation on the Gum Metal samples was observed. Gum Metal presented excellent properties making it a suitable candidate for biomedical applications.

Mechanical, corrosion, and wear properties of biomedical Ti–Zr–Nb–Ta–Mo high entropy alloys

The microstructures, mechanical, corrosion, and wear behaviors of the TixZrNbTaMo (x = 0.5, 1, 1.5, and 2, molar ratio) high entropy alloys (HEAs) were studied. It was found that the Ti–Zr–Nb–Ta–Mo HEAs showed a dendrite structure with two body-centered-cubic (BCC) solid solution phases. The Ti0.5ZrNbTaMo HEA exhibited a high hardness of about 500 HV, high compressive strength approaching 2,600 MPa, and large plastic strain of over 30%. Furthermore, the highly-protective oxide films formed on the surface of Ti–Zr–Nb–Ta–Mo HEAs in the phosphate buffer saline (PBS) solution, which resulted in the high corrosion resistance of the HEAs. The Ti–Zr–Nb–Ta–Mo HEAs exhibited the greater dry- and wet-wear resistance than that of the traditional biomedical Ti6Al4V alloy. The results also indicated that with the decrease in the Ti content, the wear resistance of the Ti–Zr–Nb–Ta–Mo HEAs in the PBS solution improved. Finally, the Ti0.5ZrNbTaMo alloy presented the highest corrosive wear resistance among the four HEAs owing to its combination of good mechanical properties and high chemical stability.

Developing a New Beta‐Type of Ti–Si/Sn Alloys for Targeted Orthopedic Therapeutics: Assessments of Biological Characteristics

Titanium (Ti) alloys are widely used in tissue engineering, but their applications are limited by low strength, bactericidal properties, and metal ion release. Beta Ti alloys are promising materials for load‐bearing orthopedic implants due to their excellent corrosion resistance and high biocompatibility. Herein, developed new beta‐Ti alloys including Ti–Nb–Zr–Sn (Ti–Sn) and Ti–Nb–Zr–Ta–Si (Ti–Si) to improve structural and biochemical features of the existing Ti alloys as orthopedic implants. The new Ti–Sn and Ti–Si alloys were fabricated using mechanical ball milling and spark plasma sintering techniques respectively and compared with commercially pure Ti alloys on hydrophilicity, surface characteristics and cytotoxicity, proliferative and osteogenic differentiation effects as well as biocompatibility in human bone osteosarcoma cell line (MG63). The new beta Ti alloys showed no significant differences in proliferation and cytotoxicity on the MG63 cells. Both Ti–Sn and Ti–Si alloys, compared to the commercial pure Ti, improved the biological profile and upregulated the expressions of runt‐related transcription factor 2, osterix, and collagen mRNA levels in the MG63 cells. The Ti–Si alloy showed greater cell proliferation and osteoblastic protein expression and a better biological profile compared to the Ti and Ti–Sn alloys. The novel beta Ti alloys exhibited promising potentials in orthopedic applications.

Selective laser melting of high-strength, low-modulus Ti–35Nb–7Zr–5Ta alloy

The state-of-the-art alloys for load-bearing implant applications lack the necessary functional attributes and are largely a compromise between biocompatibility and mechanical properties. While commercial alloys pose long-term toxicity and detrimental stress shielding effects, the newly developed alloys are closing in on the gaps, however, falling short of the desired elastic modulus necessary to rule out stress shielding. In this work, we report the fabrication of a low modulus β-Ti alloy, Ti–35Nb–7Zr–5Ta (TNZT), by selective laser melting (SLM) with optimized laser parameters. The as-prepared SLM TNZT shows a high ultimate tensile strength (~630 MPa), excellent ductility (~15%) and a lower elastic modulus (~81 GPa) when compared to the state-of-the-art cp-Ti and Ti-based alloys. The mechanical performance of the as-printed TNZT alloy has been examined and is correlated to the microstructure (grain structure, phase constitution and dislocation density). It is proposed that a high density of GND (geometrically necessary dislocations), resulting from rapid cooling, in the as-prepared condition strengthens the alloy, whereas the single phase β-bcc crystal structure results in lowering the elastic modulus. High grain boundary area and a preferred crystal orientation of {200} planes within the bcc crystal lattices contribute to an additional drop in the elastic modulus of the alloy. It is shown that the TNZT alloy, processed by SLM, demonstrates the best combination of strength and modulus, illustrating its potential as a promising biomaterial of the future.

Cuboid-like nanostructure strengthened equiatomic Ti–Zr–Nb–Ta medium entropy alloy

This study investigates the effect of annealing treatment on the phase transformation and mechanical properties of the equiatomic TiZrNbTa MEA from room temperature to 1200 °C. After annealing at 1200 °C for 24h, the single solid-solution body-centred cubic (BCC) phase in the as-cast Ta25Zr25Nb25Ti25 transformed into an extremely high number density (~103/μm2) of Ta–Nb-rich BCC nanocuboidal phase (28 ± 10 nm square, BCC1) and a nanostrip-like Zr-rich BCC phase (3 ± 2 nm thick, BCC2). The phase separation from BCC to BCC1 and BCC2 arises from two primary reasons: (i) the high positive mixing enthalpy of both Ta–Zr and Nb–Zr (strong tendency to separation between each pair), and (ii) the 3–4 orders of magnitude higher mobility of Zr than Ta, Nb and Ti in these MEAs (kinetically driven). Detailed CALPHAD simulations of phase formation in this MEA agreed with experiments and provided insightful phase transformation details. The calculated diffusion distance of Zr (~4.1 nm) from the CALPHAD data corresponds to the measured Zr-rich nanostrip thickness (3 ± 2 nm). The nanocuboidal BCC1-BCC2 structure exhibited 112<111>-type of twinning deformation under compression at room temperature. The Ta25Zr25Nb25Ti25 MEA retained yield strength of ~410 MPa at 1000 °C and ~210 MPa at 1200 °C. The phase transformation during cooling after annealing and the microstructural evolution during compression at temperatures from 600 °C to 1200 °C were characterized and discussed in detail.

Comparison of Ti–35Nb–7Zr–5Ta and Ti–6Al–4V hydrofluoric acid/magnesium-doped surfaces obtained by anodizing

ObjectivesDevelopment of a new generation of stable β alloy, free of aluminum or vanadium and with better biological and mechanical compatibility and evaluate the surface properties of Ti–6Al–4V and Ti–35Nb–7Zr–5Ta after anodization in hydrofluoric acid, followed by deposition of different electrolyte concentrations of magnesium particles by micro arc-oxidation treatment. MethodsDisks were anodized in hydrofluoric acid. After this first anodization, the specimens received the deposition of magnesium using different concentration (8.5% and 12.5%) and times (30s and 60s). The surface morphology was assessed using scanning electron microscopy, and the chemical composition was assessed using energy dispersive x ray spectroscopy. The surface free energy was measured from the contact angle, and the mean roughness was measured using a digital profilometer. ResultsAnodization in hydrofluoric acid provided the formation of nanotubes in both alloys, and the best concentration of magnesium considered was 8.5%, as it was the condition where the magnesium was incorporated without covering the morphology of the nanotubes. X-ray dispersive energy spectroscopy showed magnesium incorporation in all conditions. The average roughness was increased in the Ti–35Nb–7Zr–5Ta alloy. ConclusionsIt was concluded that anodizing could be used to deposit magnesium on the surfaces of Ti–6Al–4V and Ti–35Nb–7Zr–5Ta nanotubes, with better results obtained in samples with magnesium concentration in 8.5% and the process favored the roughness in the Ti–35Nb–7Zr–5Ta group.

Electrophoretic Deposition (EPD) of Natural Hydroxyapatite Coatings on Titanium Ti-29Nb-13Ta-4.6Zr Substrates for Implant Material

This study aims to investigate the effect of the electrophoretic deposition process (EPD) of natural HA (extracted from bovine bones) with various particle size on Ti-29Nb-13Ta-4.6Zr (TNTZ) coating surfaces. HA particles were refined from bovine bone powders using planetary ball mill and then sieving to separate the particle based on its size. The maximum size according to sieving mesh size is #25 µm, #63 µm and #125 µm. The coating process was conducted by using EPD apparatus with voltage and time process 10V and 5 minutes, respectively, for each sample. The coating layer morphology was observed with Stereo Microscopy, Scanning Electron Microscopy (SEM) and the thickness was measured with Thickness Gauge. The result shows that the size of the particle determines the coating layer characteristics. The best of HA coating quality according to the implant coating standard is obtained for the 25 µm particle size with the surface coverage is 99%. The thickness is 121 µm and the ratio of chemical composition Calcium and Phosphor Ca/P) is 1,49%. These may be concluded that, on the point of view physical characteristics, natural HA from bovine bone has potential enough as a coating layer to improve the bioactivity implant for biomedical application. However, the mechanical characteristic of the layer is still needed to determine the strength of coating layer for avoiding delamination during application.

Architectured Cu–TNTZ Bilayered Coatings Showing Bacterial Inactivation under Indoor Light and Controllable Copper Release: Effect of the Microstructure on Copper Diffusion

A Ti–23Nb–0.7Ta–2Zr–1.2O alloy (at %), called “gum metal”, was deposited by direct-current magnetron sputtering (DCMS) on an under layer of copper. By varying the working pressure during the deposition, columnar TNTZ (Ti–Nb–Ta–Zr) nanoarchitectures were obtained. At low working pressures, the upper layer was dense with a coarse surface (Ra = 12 nm) with a maximum height of 163 nm; however, the other samples prepared at high working pressures showed columnar architectures with voids and an average roughness of 4 nm. The prepared coatings were characterized using atomic force microscopy (AFM) for surface topography, energy dispersive X-ray spectroscopy (EDX) for atomic mapping, scanning electron microscopy (SEM) for cross-section imaging, contact angle measurements for hydrophilic/hydrophobic balance of the prepared surfaces, and X-ray diffraction (XRD) for the crystallographic structures of the prepared coatings. The morphology and the density of the prepared coatings were seen to influence the hydrophilic properties of the surface. The antibacterial activity of the prepared coatings was tested in the dark and under low-intensity indoor light. Bacterial inactivation was seen to happen in the dark from samples presenting columnar nanoarchitectures. This was attributed to the diffusion of copper ions from the under layer. To verify the copper release from the prepared samples, an inductively coupled plasma mass spectrometer (ICP-MS) was used. Additionally, the atomic depth profiling of the elements was carried out by X-ray photoelectron spectroscopy (XPS) for the as-prepared samples and for the samples used for bacterial inactivation. The low amount of copper in the bulk of the TNTZ upper layer justifies its diffusion to the surface. Recycling of the antibacterial activity was also investigated and revealed a stable activity over cycles.

Processing a biocompatible Ti–35Nb–7Zr–5Ta alloy by selective laser melting

Abstract

High pressure torsion induced lowering of Young's modulus in high strength TNZT alloy for bio-implant applications

An exceptional combination of low Young's modulus (E ~68 GPa) and high flow strength (σf ~1 GPa) was achieved for a consolidated β-Ti-based metastable Ti-35Nb-7Zr-5Ta (TNZT) alloy subjected to room temperature high-pressure torsion (HPT). The mechanical properties of the alloy were studied by quasistatic nanoindentation tests at different strain rates, where a reduction in Young's modulus E ~73 GPa (NHPT10) and E ~68 GPa (NHPT40) is observed together with an increase in plastic deformability (or HPT rotations). The microstructure evolution with increasing shear strain has been investigated. The stabilized bcc β-Ti phase with homogeneous nanostructure distribution was observed leading to a low Young's modulus. Severe straining causes a uniform hardness distribution without any noticeable change in the strength of the material. This study may be useful for developing excellent removable implant materials.

TZNT alloy for surgical implant applications: A Systematic Review

Nowadays, Ti–Nb–Ta–Zr (TZNT) alloy have attracted attention as new titanium alloy material for surgical implant applications due to its biocompatibility, great corrosion behavior, low cytotoxicity, and enhanced wear resistance, biological and mechanical properties. There is a great need to improve the implant properties which can be achieved through a combined solution of titanium alloy (TNZT) with low elastic modulus in the physiological environment of the body. Moreover, it protects the surgical implant from inflammation, infection, adverse soft tissue reaction to particulate debris and implant fracture. Therefore this review aimed to improve the quality of the surgical implant applications to enhance the working life and prevent failure by adding four matrices containing niobium, zirconium, tantalum, and silicon. Hence, TZNT alloy can be developed to be a promising candidate for biomedical applications especially in surgical implant applications.

Microstructure, mechanical property and corrosion behavior of porous Ti–Ta–Nb–Zr

In this paper, biomedical porous Ti–Nb–Ta–Zr with 40% porosity and 166 ± 21 μm macro-pore size was successfully fabricated by space holder method. The microstructure, Vickers hardness, compressive and electrochemistry behavior were studied. It results that a few second phases exist in β matrix of the porous Ti–Nb–Ta–Zr. Its Young's modulus is 0.8 GPa, close to 0.01–3 GPa for trabecular bone. The total recovery strain ratio and pseudoelastic strain ratio are 8.8% and 2.7%, respectively. It fails mainly by brittle cleavage with the fan-shaped and smooth cleaved facets. Although, local ductile fracture by a few dimples and a small amount of transcrystalline fracture with the cleavage of similarly oriented laths in a colony are observed on the fracture surface. The impedance spectrum of porous Ti–Nb–Ta–Zr has the characteristics of half capacitive arc resistance, showing good corrosion resistance in SBF solution.

Composition and origin of Ti–Nb–Ta–Zr bearing minerals in the Abu Diab highly evolved granite from the Central Eastern Desert of Egypt

The central Eastern Desert (CED) of Egypt is well-known for its granite-related Nb–Ta mineralization. The garnet-bearing muscovite granite (GMG) of the Abu-Diab composite pluton in the CED consists mainly of quartz, K-feldspar (Or88–98), albite (An0-4) and muscovite, with accessory minerals including garnet, zircon, columbite, ilmenite, Ti-rich hematite, rutile, ilmenorutile, thorite, apatite, xenotime and chlorite. The GMG is weakly peraluminous and has low Nb/Ta (9.6–15.4) and Zr/Hf (16–31) with discernible REEs tetrad effect (TE1-3 = 1.11–1.35), typical of highly evolved granites. Zircon contains high concentrations of U and Th typical of late-magmatic zircon and similar to zircon type from highly evolved granite. The homogenous and weak zoned columbites are classified as manganocolumbite. The formation of Ta-rich rim in the columbite may indicate that later fluids were from the GMG granite itself at advanced fractionation into exsolving fluids, and not from an external source. Ilmenite is greatly enriched in MnO, which indicates the significant pyrophanite (up to 29 mol %) molecules in ilmenite through simple substitution of Mn for Fe2+ with increasing oxygen fugacity under magmatic-hydrothermal conditions. Xenotimes show low analytical totals, suggesting probably hydration during their post-magmatic alteration, while apatite is small-grained associated with tiny zircons, suggesting late-crystalized phases. During late magmatic differentiation stage, the interaction of granitic melt with F-rich late magmatic fluids could be resulted in the formation of Ti–Nb–Ta–Zr minerals. Overall, the Abu Diab GMG possesses mineralogical and geochemical features that make it a potential target for Ti–Nb–Ta–Zr minerals.