Ti6A14V Alloy Research Articles

Momentum and thermal transport analysis in MHD nanofluid through the thermally heated square conduit: Finite element method

ObjectiveThe purpose of this investigation is to report the thermal performance of water-based nanofluids with two different types of hybrid nanofluids for the cooling process of the radiator inside the thermally heated square cavity under the addition of thermal radiation and magnetic field by using the finite element method. Research gapThe heat transfer analysis of MHD nanofluid with the suspension of titanium alloy Ti6A14V and aluminum alloy AA7075 in cavity flow problems under the effects of thermal radiation and thermal boundary conditions by using the Galerkin finite element method is not reported before. NoveltyIn this numerical investigation, the novel mathematical model of two types of titanium alloy Ti6A14V (class of titanium) and aluminum alloy AA7075 is proposed first time in the cavity flows under the influence of a uniform magnetic field and non-uniform thermally heated bottom wall. The momentum and energy equations are updated with terms of magnetic field and thermal radiation, respectively. The cavity is filled with AA7075- Ti6A14V/water nanofluids. Two parallel vertical walls of the cavity are set at constant temperatures (Tc) and the top one is adiabatic while the temperature at the lower wall is taken as the variable. Method of solutionThe physical model is composed in terms of nonlinear differential equations and transformed into a dimensionless form by using suitable non-dimensional quantities. The Galerkin finite element method along with iterative Newton’s Raphson method is selected to simulate the problem and obtain the numerical solution with a high degree of accuracy. The results are illustrated for fixed Prandtl number Pr=10.0 throughout the calculation, Rayleigh number 1000≤Ra≤100000, nanoparticle volume friction 0.0≤ϕ≤0.05 Hartman number 0≤Ha≤10 and thermal radiation parameter 1.0≤Ra≤10.0. Both grid independence tests and comparison tests are directed to get the accuracy of the established model. Important findingsThe computational results revealed that the aluminum alloy (AA7075) alloys nanoparticles are more productive as compared to titanium (Ti6Al4V) alloy nanoparticles in terms of enhancing the thermal features of water-based nanofluid. The aluminum alloy nanofluid and titanium alloy nanofluid provide 3.9 % & 5.7 % and 2.9 % & 4.2 % more heat transfer at the bottom and side walls as compared to regular fluid. ApplicationsThe current nanofluid models are more efficient than the conventional model to control the heat transfer rate and flow phenomena. The computational results revealed that if the radiator is assembled by using the modern concept of hybrid nanofluid then that will increase the heat transfer of the engine and enhance the lifespan of the machinery.

Studying the Insulating Properties of Oxide Films Obtained on the Ti6A14V Alloy in Tartaric Acid Solutions Using the Method of Electrochemical Decoration by Copper

The investigation data of the formation peculiarities of oxide films on the Ti6A14V alloy in tartaric acid solutions have been given. It is shown that the behavior of alloy forming dependences is conditioned by the anode current density. At ja < 0.5 A∙dm-2 the continuous oxide film is not formed on the alloy surface and the preset value of the final voltage on the cell is not reached. With an increase in ja > 0.5 A∙dm-2, alloy forming dependences show a linear behavior that is indicative of the formation of low porous films. In these conditions, the oxide film formation rate is in direct proportion to the value of ja. The electrochemical oxidation of Ti6A14V alloy in tartaric acid solutions results in the formation of interference-colored oxide films. The oxide film ultimate thickness and color are defined by the preset voltage and are independent of the current density and electrolyte concentration. The isolating properties of obtained films were studied by the way of the cathode polarization of oxidized specimens in the sulfate copper-plating electrolyte. The research done allows us to make a conclusion that electrochemical copper deposition is a convenient tool for the detection of defective spots in oxide films. It is shown that due to the specific features of the reduction kinetics of Cu2+ ions on the oxidized titanium it is reasonable to use for the studies the initial sections of polarization dependences that correspond to ΔE = 0.2–0.25 V. The alloy polarization dependences allow us to establish unavailability of apparent dependences between the oxidation current density, the electrolyte concentration, the cell final voltage value and the polarization that occurs during the Cu2+ ion reduction. The anodic connection of copper-coated specimens conditions the reversible dissolution of a greater portion of the specks of copper deposits. It is indicative of the electron conduction of film defects. The obtained data allow us to vary the electrolysis parameters in a wide range with no significant influence of the treatment mode of Ti6A14V alloy on the quality of oxide coatings.

Effect of High-Frequency Induction Carburization on Ti6Al4V Alloy Tissue and Wear Performance

The surface of Ti6Al4V alloy was rapidly carburized by high-frequency electromagnetic induction heating under vacuum. The microstructure and hardness of the carburized layer were studied. The wear properties of the carburized layer were tested at 50, 100 and 200 rpm using the end face friction and wear device, and the wear mechanism was analyzed. The results show that the TiC strengthening phase was formed on the surface of Ti6Al4V alloy after high-frequency induction carburization, and the surface grains were refined. The surface hardness reaches 1116 HV0.25, but the brittleness of the carburized layer increases with increasing temperature. The amount of wear was reduced by 54% at 100 rpm. The roughness of the wear scar was reduced from 3.26 μm to 2.28 μm of Ti6A14V alloy matrix. The coefficient of friction and wear rate increases with increasing speed. The wear mechanism was transformed from adhesive wear and oxidative wear of the substrate to abrasive wear after carburizing.

Effects of niobium (Nb) on mechanical properties of laser coated Nitinol (NiTi) used for surface modification of Ti6A14V alloy

Abstract:Laser surface treatment is widely used as an engineering technique due to its special characteristics and several advantages over other surface modification techniques. In the present study, elemental mechanically pre-alloyed powder consisting of Niobium, Titanium and Nickel was deposited onto a grade 5 Titanium alloy substrates to form a high wear resistance coating. This was such that the surface mechanical properties of the base metal can be improved. The fabricated samples were characterised using optical microscopy, scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), Differential Scanning Calorimeter (DSC), micro hardness tester and wear machine. The deposited coatings were well bonded and consisted of various phases. Hardness was seen decrease with increase in Nb content while wear resistance increasing with increase in niobium content.

Elektrokimyasal Biriktirme Yöntemi ile Hidroksiapatit (HAP) Kaplanmış Ti6Al4V İmplantlarının Korozyon Davranışlarının İncelenmesi

In this research, hydroxyapatite (HAP) has been coated on the Ti6A14V alloy surface by electrophoresis method. In this electrophoresis method, NH4H2PO4 is taken as P precursor and Ca (NO3)2.4H2O is taken as Ca precursor to obtain HAP coating. Additionally, 5 N NaOH pre-treatment surface operation (PTSO) has been applied to Ti6A14V. PTSO are effective on clinging of HAP coating to the surface. The corrosion behaviours of uncoated and HAP coated samples are examined in simulated body fluid (SBF) after for holded 7, 14, 21 and 35 days in SBF. HAP coatings have obtained by electrophoresis method was not showed inhibition for preventing corrosion. The surface images of the samples were described by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDX), and X-ray diffraction (XRD). From SEM images have been observed open pores and connections among pores in the coating, which increases osteointegration. It is noted in EDX analyses of the surfaces of the HAP coated samples that there is Ca, O and P on the surface. It is seen in XRD analysis of HAP coated samples that there are TiO2, HAP and calcium phosphate structures on the surfaces.

Atomic layout of an orthodontic titanium mini-implant in human tissue: Insights into the possible mechanisms during osseointegration

To evaluate nanoscale molecular interactions in the interface between human bone and orthodontic titanium implants. An orthodontic implant (sandblasted with large grit and with an acid-etched surface treated with Ti6A14V alloy) retrieved from the mandible of human after 2 months of healing was used to analyze the molecular interactive mechanism between the implant and the surrounding bone tissue. To preserve the natural state of the sample as much as possible, cryofixation and scanning electron microscope/focused ion beam milling without any chemical treatment were used during sample preparation. Atom probe tomography was used to investigate the chemical composition and structure at the interface between the implant and human bone tissue. Three-dimensional (3D) reconstruction of the whole sample revealed a 20 × 50-nm2 plate-like bony element diffusion layer in the sample. The iso concentration analysis of the diffusion layer indicated that the bony element, calcium, and the implant element, titanium oxide, were interspersed with each other. Detailed ionic distribution was illustrated by 3D reconstruction with partial region of interest and one-dimensional concentration profiles of the implant-bone interface. The study results advance nanoscale understanding of osseointegration and suggest a potential nanostructure for increasing bond strength of biomaterials to bone.

Kinetic features of wear-resistant coating growth by plasma electrolytic oxidation

The kinetic features of coating growth on titanium alloy Ti–6A1–4V by plasma electrolytic oxidation (PEO) are investigated. It was observed that the coating growth rate decreases significantly with the increasing of the PEO time treatment. At the same time, large longitudinal pores (cracks) were formed; thus, the major part of the coating is separated from the substrate. Coating growth is realized by the two mechanisms: (a) migration-diffusional and (b) thermochemical treatment of the deposited aluminum hydroxide (electrolysis) and oxidation of the substrate at the bottom of the coating pores. It presumably occurs due to the saturation of the electrolyte in the pores with titanium hydroxide and the relatively low intensity of the microdischarges, which is insufficient to eject the substance from the channels for ‘pancake’ formation. This increases the amount of the aluminum titanate (TiAl2O5) in the coating. The latter presumably forms due to a eutectic reaction in the coating or due to the exothermic reactions of titanium dioxide formation. The TiAl2O5-based coating containing at least 10% aluminum oxide α-Al2O3 (more than 20% in the outer layer) and 11% titanium dioxide (TiO2) increases the wear resistance of the titanium alloy at least six times.

Osteogenic potential of a novel microarc oxidized coating formed on Ti6Al4V alloys

In order to improve the biocompatibility, Ti6Al4V alloys are processed by micro arc oxidation (MAO) in a novel electrolyte of phytic acid, a natural organic phosphorus-containing matter. The MAO coatings were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and X-ray photoelectron spectroscopy (XPS). The cytocompatibility of Ti6A14V alloys before and after MAO were comprehensively evaluated. The results showed that the fabricated MAO coatings were composed of rutile, anatase, TiP2O7 as well as some OH− groups, exhibiting the excellent hydrophilicity and a porous structure with small micro pores. No cytotoxicity towards MC3T3-E1cells was observed in this study. In particular, MAO treated Ti6Al4V alloys presented comparable cell adhesion and proliferation as well as significantly enhanced alkaline phosphatase activity, extracellular matrix (ECM) mineralization and collagen secretion in comparison with the untreated control. The results suggest that the Ti6Al4V alloys treated by MAO in phytic acid can be used as implants for orthopaedic applications, providing a simple and practical method to widen clinical acceptance of titanium alloys.

Hydroxyapatite Coating of Ti6A14V Alloys in Alanin-Alanin Sodium Salt Environment with Biomimic Method

Hydroxyapatite Coating of Ti6A14V Alloys in Alanin-Alanin Sodium Salt Environment with Biomimic Method Biomimetic is an expression used to define the substances, tools, mechanism, a systems created by humans through imitating the systems existing in the nature. With this method the surfaces of base materials activated by various chemicals are coated inside synthetic body fluid (SBF) that is created in the laboratory ground by using the method of defecation. As coating is conducted in an environment which has synthetic body fluid, biomaterials that are completely harmonious with the body can be obtained. In this study it is aimed to create hydroxyapatite (HA) coating that is completely harmonious with human blood plasma, in Alanin and Alanine Sodium Salt environment by using biomimetic technics for the first time in literature and to analyse it. In the process of HA coating, Ti6A14V alloyed implant materials have been used as base material. In the study, implant materials having Ti6Al4V alloy have been first sandpapered and then they were washed first with pure water and then with acetone. The materials that were also cleaned inside the ultrasonic bathroom, have been waited for 1 day in the 100 mL 5M NaOH + 0,5 mL H 2 O 2 solution in drying-oven for being activated. Later on NaOH was transferred and the materials were washed with pure water. Afterwards it is left to dry at 60 oC for 24 hours. After being dried, it was waited for 1 hour at 600 oC and than cooled. With the completion of this process, the synthetic body fluid solution (2L) was obtained with the temperature at 37 oC and pH value at ~7,4. Coating process was realised inside SBF with waiting periods of 24, 48, 72, and 96 hours. Relating to the coatings obtained by biomimetic method, surface smoothness and thickness specifications have been determined, their micro structure has been analysed by using Scanning Electron Microscope (SEM), the elementary analyses namely Energy Dispersive X-ray Spectroscopy (EDS) for the surfaces of coating have been determined and X-Ray Diffraction (XRD) analysis have been conducted for obtaining information regarding phases and the concentrations of the phases. The results obtained from the study have been evaluated and discussed.

Investigation of Material Properties of Layered Al-Ti Material with the Use of Microspecimens

The article presents a monotonic tensile test of two materials: aluminum alloy AA2519 and titanium alloy Ti6A14V joined by means of explosive welding. The specimens were cut out in such a way that some consisted of only titanium alloy some were made of only aluminum alloy, whereas the third series were specimens consisting of both material alloys together with the bonding layer. The main goal of the research was to compare changes in the materials fatigue properties caused by explosion welding of these two alloys.

Evaluation of the mechanical and corrosion protection performance of electrodeposited hydroxyapatite on the high energy electron beam treated titanium alloy

In our present study, the Ti–6Al–4V alloy surface was modified by irradiating with the high energy low current DC electron beam (HELCDEB) using 700keV DC accelerator. Following this, the HELCDEB treated surface was coated with hydroxyapatite by adopting electrodeposition method. The microstructure and hardness of HELCDEB treated Ti–6A1–4V alloy with and without electrodeposited hydroxyapatite were investigated. Also, the electrochemical corrosion characteristics of the samples in simulated body fluid (SBF) was studied by potentiodynamic polarisation and electrochemical impedence techniques (EIS) which showed an enhanced corrosion resistance and revealed an improved life time for the hydroxyapatite coating developed on the HELCDEB treated Ti–6A1–4V alloy than the untreated sample.

Effects of weld cross-section profiles and microstructure on properties of pulsed Nd:YAG laser welding of Ti6Al4V sheet

In this study, the influence of weld cross-sectional profiles and microstructure, under different welding conditions, was investigated on the mechanical properties of pulsed Nd:YAG laser-welded joint of Ti6A14V alloy. The V- and H-shaped weld cross-section profiles were obtained under low and high heat input, respectively. The microstructure in the fusion zone (FZ) of V- and H-shaped welded joint consisted of a fine acicular martensitic α′ solidification structure within the prior-β grains, responsible for the maximum hardness in the FZ. Tensile tests revealed that the V-shaped welded joint fractured at the near heat-affected zone (HAZ)/base metal (BM) interface, but the H-shaped welded joint fractured in the BM. Furthermore, the tensile strength of the V-shaped welded joint was lower than that of the H-shaped welded joint. This was attributed to the fact that the heterogeneity of strain distribution at the interface of HAZ and BM of the V-shaped welded joint was greater than that of the H-shaped welded joint during tensile process.

EFFECT OF CUTTING CONDITIONS ON THE SERRATED CHIP FORMATION IN HIGH-SPEED CUTTING

Titanium alloy Ti6A14V has been widely used in many engineering fields due to its attractive specific strength and corrosion resistance. A deep understanding of the material's machinability is of primary importance. This article investigates the serrated chip formation mechanism of Ti6Al4V alloy under high-speed cutting by finite element analysis. The effect of the cutting conditions on the serrated chip formation is analyzed comprehensively. The study found that when the initial chip thickness becomes small or when the rake angle becomes large, the size of sawtooth decreases and the number of sawtooth increases. The serrated chip morphology is more sensitive to the initial chip thickness. The severe fluctuation of cutting forces is caused by the formation of sawtooth in chipping. To minimize the serrated chipping in high-speed machining, the initial chip thickness is the most important factor to consider.

On the dynamic character of localized failure

The dynamic stored energy of cold work (SECW) has recently been identified as the trigger for adiabatic shear failure. However, the question of what makes the failure “dynamic” has remained open so far. Using compression tests (Ti6A14V alloy) over a wide range of strain rates [10 −4 –10 4 s −1 ], we have identified a transition strain rate above which both the dynamic SECW and the microstructure are radically different from their static counterparts, thereby outlining the onset of “dynamic” failure.

Biomechanical effects of the distance from the fracture zone to the interlocking fixation screw of intramedullary nail

The goal of any internal fixation produce is to increase the stability of fractures, to transfer load across the fracture site, and to maintain anatomic alignment to induce bony union. While there is general agreement on the usefulness of intramedullary fixation techniques, the method has been criticized because of technical difficulties and mechanical failures. Intramedullary nails are load-sharing devices, allowing the bone to transmit compressive forces while maintaining axial alignment. The function of an intramedullary nail to facilitate healing is secured by its stiffness, which is usually expressed according to load directions as bending or torsional stiffness. Nail stiffness has been determined in a large number of studies. Nail design influences both bending and torsional stiffness. Important parameters are nail diameter, nail material, cross-section (open vs. closed) and design of the screw/nail interface. Nail strength is influenced by material, design and manufacturing properties. The video extensometer markers were placed on distal and proximal side of the fracture. The displacements between the markeres were measured with two non-contact CCD camera extensometers (Non-contact Video Extensometer DVE-101/201, Shimadzu, Japan). The axial compression was applied to all materials with the loading speed of 5 mm/min (max. 800 N). Biomechanical test, axial compression, was performed on materials. In present study, standard intramedullary nails with 11 mm diameter and 400 mm length are used. The intramedulary nails are Ti–6A1–4V alloys. Fracture gap of the models was 10mm. In three different groups, nine tests in each one were carried out. The intramedullary nail distance of the screws was 210 mm in the first group, 110 mm (between two distal gaps) in the second group and six screw fixed in the third groups. Polyethylene materials with 210 mm length are fixed to each intramedullary nails. Results of compression tests of all groups are evaluated and compared statistically. According to statistical assessment there is significant change between each three groups. In a recent, more detailed comparative study it was shown, that significant variations in axial rigidity exist between the proximal and the distal segment of certain nails, and that more screw do not always lead to increased stiffness. If the interface is insufficient, the load on the bone will be taken mostly by the screw holes through the screws instead of by the nail body; however, the screw holes are the weakest part of the nail. Local stress peaks in the region of the interlocked screws can lead to a material failure of the bone, which can result in complications such as nail or screw brake-down and bone refracture.

Titanium Alloy Lattice Structures with Millimeter Scale Cell Sizes

AbstractTitanium sandwich panels with cellular cores of a uniform 1–5 mm diameter open cell size are well suited for impact energy absorption and cross flow heat exchange applications. Periodic cellular structures (lattices) made from high specific strength, high temperature alloys are preferred for these multifunctional uses. A diffusion bonding method has been applied here to make cellular lattice structures from a Ti–6A1–4V alloy. To illustrate the approach, lattice structures with both square and diamond collinear topologies, a 2 mm open cell size, and a relative density of 15% were made from 254 µm diameter titanium alloy wires. These structures were found to have a compressive strength of 40 ± 5 MPa that was controlled by plastic yield followed by buckling of the struts. The cellular structures have been brazed to titanium alloy face sheets to create sandwich panel structures that appear well suited for multifunctional applications up to 420 °C.

Osteoconductive and Osteoinductive Properties of Zeolite MFI Coatings on Titanium Alloys

AbstractThe use of zeolite MFI‐coated titanium alloy for bone cell growth and new bone formation in vitro is investigated. The corrosion‐resistant MFI coating is shown to be osteoconductive and to promote proliferation of human fetal osteoblasts (hFOBs) as compared to bare titanium alloy, Ti6Al4V. The zeolite crystal microstructure appears to facilitate osteoblast adhesion and induces osteointegration, as evaluated with microscopy. In addition, the zeolite promotes the differentiation of hFOBs into mature osteoblasts, as well as the production of a mineralized matrix at earlier times in culture compared to Ti6Al4V, indicating higher osteoinductive properties of the MFI coating than titanium alone. A significant increase in the expression of the bone morphogenetic protein (BMP‐2) gene is measured in hFOBs cultured on zeolite coatings compared to bare Ti6Al4V. This is the first report on highly corrosion‐resistant zeolite MFI coatings on Ti6A14V alloys with the potential to be used as a material of improved osteointegration appropriate for bone tissue regeneration.

The influence of SiO 2 and SiO 2–TiO 2 intermediate coatings on bond strength of titanium and Ti6Al4V alloy to dental porcelain

Objectives The purpose of this study was to evaluate the bond strength of commercially pure CPTi and Ti6Al4V alloy with SiO 2 and SiO 2–TiO 2 intermediate coatings to Triceram low-fusing dental porcelain. Methods The multilayered systems were characterized from the standpoint of microstructure analysis (SEM), the mode of failure, the nature of bonding and the influence of intermediate coatings on the improvement of bond strength. The SiO 2 and SiO 2–TiO 2 intermediate coatings were applied on the substrate materials by the sol–gel dipping technique. The metal–ceramic bond strength was investigated according to ISO 9693 standards using the three-point flexure bond test. Results Statistically significant higher bond strength of the metal–porcelain for Ti6A14V alloy (28.24 MPa), Ti6Al4V/SiO 2 (32.17 MPa) and Ti6Al4V/SiO 2–TiO 2 (36.09 MPa) was noted in comparison to CPTi (23.04 MPa), CPTi/SiO 2 (27.98 MPa) and CPTi/SiO 2–TiO 2 (28.84 MPa), respectively. The nature of metal-intermediate coating–porcelain bonding was both mechanical and chemical. The failure in all systems was cohesive and adhesive, mainly adhesive. Significance The application of SiO 2 and SiO 2–TiO 2 intermediate coatings, produced by the sol–gel method, to both CPTi and Ti6Al4V alloy significantly improves the bond strength of metal–porcelain systems in comparison to the metal substrate only after sandblasting, and may have clinical use.

Thin calcium-phosphate coatings produced by RF magnetron sputtering and prospects for their use in biomedical engineering

Thin calcium-phosphate coatings with thickness less than 2.7 m were prepared by radio-frequency magnetron sputtering technique on the surfaces of pure titanium, titanium alloy Ti6A14V and stainless ASTM 316. Results of scanning electron microscopy showed that all coatings were dense and poreless and did not have any visible defects or microcracks. Rutherford backscattering (RBS) revealed a prepared coating consisting only of calcium 33.6 (1.6 at%, phosphorous 16.5 (1.5 at%, and oxygen 48.6 (1.2 at%. The concentration of each above-mentioned element through the coating was almost constant. The physicomechanical properties of the prepared coatings were investigated using a nanoindentation technique. The values of nano-hardness and Young's modulus calculated on the basis of the obtained data were 10 GPa and 113 GPa, respectively. These values were higher than that of non-coated substrates, except titanium alloy due to the sputtering mechanism. It was found that the coating with a thickness less than 1.6 ?m possessed more adhesion strength than coatings with greater value of thickness. However, we suggest that all coatings have great cohesive resistance that does not depend on the coating thickness.

In vitro biomimetic deposition of apatite on alkaline and heat treated Ti6A14V alloy surface

Titanium alloy (Ti6A14V) substrates, having the ability of biomimetic calcium phosphate-based materials, especially hydroxyapatite deposition in a simulated body fluid (SBF) means of chemical treatment (alkaline treatment) and subsequent heat treatment, was studied. The effects of alkaline treatment time, concentration and heat treatment temperature on the formation of calcium phosphate (carbonate-hydroxyapatite) on Ti6A14V surface were examined. For this purpose, the metallic substrates were treated in 0, 5 and 10 M NaOH solutions at a temperature of 60 or 80°C for 1 and 3 days. Subsequently the substrate was heat-treated at 500, 600 and 700°C for 1 h for consolidation of the sodium titanate hydrogel layer. Finally, they were soaked in SBF for 1 and 3 days. The substrate surfaces were characterized by the techniques commonly used for bulk material such as scanning electron microscopy (SEM) and thin film X-ray diffraction (TF-XRD). With regard to the SEM and TF-XRD results, the optimum process consists of 3 days soaking in 5 M NaOH in 80°C and subsequent heat treatment at 600°C for 1h. It is worth mentioning that the results showed that the apatite formed within 3 days on the specimen surfaces, however, there was no sign of apatite formation in the control samples (without alkaline and heat treatment) which was treated for up to 3 days immersion in SBF.