Production Of Titanium Alloys Research Articles

Manufacturing antibacterial Ti-6Al-4V alloys by using NanoAg particles synthesized by reduction method for biomedical applications

Titanium alloys are among the widely used biomedical materials due to their biocompatibility and mechanical performance. It is an indisputable fact that the materials used in this area must be antibacterial. Therefore, in this study, the production of antibacterial Titanium alloys using NanoAg particles for use in biomedical applications was investigated. First, Ti-6Al-4 V titanium alloys were produced by the powder metallurgy method, which includes blending, pressing and sintering processes. Nano silver particles were synthesized by a chemical reduction method using silver nitrate and glucose. The resulting solution was subjected to Ag + ions and glucose determinations, pH and turbidity analysis. Nano Ag application was carried out by two different methods; dipping and coating method. The obtained samples were analyzed by scanning electron microscopy (SEM) and optical microscopy. Additionally, as the main purpose of this study, antibacterial analysis against Escherichia Coli and Staphylococcus Aureus was performed by percentage reduction test. While the coating method was seen to be more successful in antibacterial tests, the overall Nano Ag application performance was found to be higher against Escherichia Coli bacteria. Being that the sample containing 5% Nano Ag titanium alloys produced with the coating technique showed 100% killing effect against both Staphylococcus aureus and Escherichia coli.

Influence of Nitride Coatings on Corrosion Resistance and the Biocompatibility of Titanium Alloy Products

The bioadhesion of bacteria to the surface of samples with Ti–TiN, Zr–ZrN, Zr–(Zr, Nb)N, and Zr–(Zr, Hf)N coatings was studied via incubation with gram-positive strains of Staphylococcus aureus. The samples were kept at 25 °C for 30 days in a 3% NaCl solution. The deposition of coatings slows, whereas oxidation processes intensify. The oxygen content on the TiN and (Zr, Nb)N coating surfaces was higher than that of the Ti sample without a coating. Samples with ZrN and, especially, (Zr, Hf)N coatings resist oxidation better. Regarding bioactivity toward S. aureus, the highest density of biological forms was observed on the surfaces of TiN and (Zr, Hf)N coatings. The lowest density was on the surfaces of uncoated, ZrN-coated, and (Zr, Nb)N-coated samples. On Ti–TiN, Zr–ZrN, and Zr–(Zr, Nb)N coatings, the formation of surface biostructures of a filamentary type was observed. In the uncoated sample, the biostructures have an island character, and in the sample with a Zr–(Zr, Hf)N coating, the formation of extensive areas of biostructures was observed. Between the biostructures and coating, a layer 5 to 15 nm thick was observed, presumably associated with bacterial adhesion. The presence of biostructures on the coating surface can activate or slow oxidation processes.

Production of Medical Titanium Alloys with a Reduced Modulus of Elasticity by Selective Laser Melting. Review

Production of Medical Titanium Alloys with a Reduced Modulus of Elasticity by Selective Laser Melting. Review

Features of the Application of Coatings Based on the ZrN System to Increase Resistance to Mechanical Wear and Corrosion of Titanium Alloy Products

The coatings of ZrN, (Zr,Ti)N, (Ti,Zr,Hf)N and (Ti,Zr,Nb)N deposited on the titanium alloy substrate were compared. The wear resistance in the pin-on-disk test together with the Al2O3 indenter and the corrosion resistance in 3.5% NaCl solution were studied. It was found that the (Zr,Nb,Ti)N coating has the best resistance to wear, but has low corrosion resistance. The (Ti,Zr,Hf)N coating, on the contrary, has the best corrosion resistance, but low resistance to wear. The ZrN coating has good corrosion resistance combined with good resistance to wear. This coating is best suited for use in friction conditions with a ceramic counterbody under the influence of seawater. An important resource for increasing the properties of coatings is increasing their adhesion to the substrate, which can be achieved in two combined ways: (1) complete removal of the original oxide layer from the surface of the substrate and (2) the use of optimal compositions of the adhesive sublayer, which have not only high adhesive properties in relation to both the substrate and the coating, but also high strength. While the introduction of Nb into the ZrN coating composition increases wear resistance and the introduction of Hf increases corrosion resistance, the ZrN coating without additives best resists wear and corrosion simultaneously.

Numerical Modeling of Electron Beam Cold Hearth Melting for the Cold Hearth

The electron beam cold hearth melting (EBCHM) process is one of the key processes for titanium alloy production. The unique characteristic of this pyrometallurgy process is the application of the cold hearth, which is responsible for controlling the Low-Density Inclusions (LDIs) and High-Density Inclusions (HDIs) in the melt. As a key process of inclusion removal, the information such as melt residence time in the cold hearth is directly related to the control of metallurgical defects in the ingot, and may also affect the composition distribution of the ingot. In this paper, the details for the physical phenomena, namely the evolution of the pool, the evolution of the flow, and the evolution of the component in the cold hearth during EBCHM are investigated using a modified multi-physical numerical model. The effects of melting temperature and melting speed on these phenomena were investigated. The purpose is to provide more fundamental knowledge and to further enhance the applications of EBCHM for more titanium alloys.

Electrochemical characteristic and microstructure of Ti-6Al-7Nb alloy by centrifugal casting for orthopedic implant based on ageing time variations

The alternative Ti-6Al-7Nb alloy has gained extensive progression due to its ability to eliminate the cytotoxicity of vanadium (V) in Ti-6Al-4V alloy for orthopedic implants. The production of titanium alloys by centrifugal casting shows significant potential to reduce costs. Heat treatment and aging can tailor the microstructure and improve the corrosion resistance of titanium alloys. This study examines the effects of various ageing times on the microstructure and corrosion resistance of a centrifugal cast Ti-6Al-7Nb alloy that has previously been heated and treated at a temperature of 1050 °C, and subsequently cooled to room temperature in argon atmosphere gas. Ageing was carried out at a temperature of 550 °C with variable times of 0, 4, 6, and 8 hours. The surface morphology, metal phase changes, and electrochemical characterization were tested using an optical microscope (OM), X-ray diffraction (XRD), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). The basket-weave microstructure is formed where globularization occurs in some phases as ageing time increases. Increasing the FWHM α value is correlated with increasing the amount of α' martensite phase. As an ageing time enhances, the temperature might offer a greater driving constrain for the nucleation and expansion of the lamellar phase (α). Ageing of 8 hours has the lowest corrosion rate, 0.0023 mpy and highest corrosion resistance, 90457 Ω∙cm2, due to the partially bimodal structure and grain refinement with a smallest grain size of 327.87 µm. Tafel polarization results show that all passivated samples are stable in the Solution Body Fluid (SBF). This work can be used as a starting point for developing microstructural evolution in titanium alloys

A Combined Experimental and Numerical Calibration Approach for Modeling the Performance of Aerospace-Grade Titanium Alloy Products

Finite element modeling for designing and optimizing lightweight titanium aerospace components requires advanced simulation tools with adequate material modeling. In this sense, a hybrid strategy is proposed in this work to identify the parameters of the Johnson–Cook plasticity and damage laws using a combined direct-inverse method. A direct calibration method for plasticity law is applied based on the literature-reported data of strain-stress curves from experimental tensile tests at different temperatures and strain rates. The triaxiliaty-dependent fracture parameters of the Johnson–Cook damage law at reference conditions of strain rate and temperature (d1, d2, and d3) are calibrated with the direct method based on new data of experimental evolution of computed average fracture strain with the average stress triaxiality. The validation is performed with numerical results from an accurate micromechanics-based Ti64 model. The inverse calibration method is used to determine the strain rate and temperature-dependent damage parameters (d4 and d5) through large strain simulations of uniaxial tensile tests. The numerical results, including average strain and necking profile at fracture, are then utilized to calculate stress triaxiality by the Bridgman criterion for adjusting parameters d4 and d5. The calibrated model yields a 2.1% error for plasticity and 3.4% for fracture predictions. The experimental and simulated load-bearing capacity using the micromechanics damage model differed by only 1%. This demonstrates that the SC11–TNT model of Ti64 is reliable for identifying the Johnson–Cook damage law through the accurate use of inverse methods. The hybrid calibration strategy demonstrates the potential capability of the identified Johnson–Cook model to accurately predict the design load-carrying capacity of Ti64 aerospace components under different deformation rates and temperatures while accounting for material damage effects.

Research Progress of Preparing Titanium Alloy By Molten Salt Method

Titanium alloy has excellent characteristics that cannot be compared with other metals such as light specific gravity, high specific strength, wide applicable temperature range, corrosion resistance, and hydrogen storage. The traditional titanium alloy smelting process is mainly based on titanium sponge as raw material, which has a long process, high energy consumption, heavy pollution, and other problems, which seriously restricts the sustainable development of titanium alloy in the world. The common methods of preparing titanium alloy are alloy melting, metal thermal reduction, powder metallurgy, and the gradually emerging molten salt electrolysis. Among them, molten salt electrolysis is recognized as the most promising method to replace the traditional titanium alloy production process, and certain achievements have been made in recent years in terms of both process and basic theory research. In this paper, the common processes of titanium alloy preparation by molten salt electrolysis at home and abroad, such as molten salt electrolytic co-deposition method, cathodic alloying method and liquid cathode method, new FFC method, and its derived SOM method, etc., will be summarized systematically, and the future research will be put forward.

Demin K.A. Role of pulsed electron beam treatment in forming of operational properties of working surfaces of biomedical titanium alloy products

The article presents the study of the effect of pulsed electron beam treatment on the surface roughness of samples made of titanium alloy VT-6, obtained by two methods: mechanical processing and additive manufacturing. It has been established that electron beam treatment allows reducing the roughness of titanium alloys in both cases, which can be extremely important for polishing small-sized products, particularly those with low mechanical strength or unique microrelief surface.

Experimental Analysis of Fatigue Crack Path for Strained Functionally Graded Materials

This paper experimentally discusses crack paths in strained Functionally graded materials under constant loading conditions and vibration fatigue. The objective is to synthesize the body of knowledge on the stability of FGM. The article presents the development, production, and characterization of multi-Al (aluminum), Ni (nickel), and Titanium alloys. FGM it was successfully modified using the powder metallurgical technique. Five-layer FGM samples frequently utilize (Al, Ni), on one end and (Al-Ni-Ti) on the first. FGM sample mechanical characteristics have been investigated using wear and Fatigue testing. The Al/Ni/Titanium FGM compact specimen approaches the yield stress and ultimate stress values, which is regarded as a significant improvement in mechanical qualities with less weight. The test findings are for a constant amplitude load fully reversed with zero mean stress. The stress life approach examined three samples' fatigue characteristics and natural frequency under random vibration.

Hydrogen sintering, microstructure, and mechanical properties of Ti-10V-2Fe-3Al alloys prepared by the blended elemental method

This investigation utilized an economical hydrogen sintering technique to fabricate the Ti-10 V-2Fe-3Al aerospace alloy. We examined the phase and microstructural evolution throughout the densification, hydrogen sintering, and dehydrogenation processes. Hydrogen dissolution prompted titanium deformation, culminating in an ultrafine-grained microstructure reinforced with α-phases. Notably, the hydrogen-sintered alloy showcased a microstructure comparable to that of forged alloys, diverging from traditional sintering approaches. Enhanced tensile and yield strengths were also documented. Collectively, hydrogen sintering presents a viable avenue for augmenting the microstructures and mechanical attributes of economically efficient titanium alloy products.

Effects of HIP Process Parameters on Microstructure and Mechanical Properties of Ti-6Al-4V Fabricated by SLM

Ti-6Al-4V titanium alloy products formed by selective laser melting (SLM) are characterized by high strength and low plasticity. In addition, there may be pores inside the material, which may become a fracture sprouting point and accelerate the failure of the parts. Using an optical microscope (OM), scanning electron microscope (SEM), and electronic universal testing machine, the effects of hot isostatic pressing (HIP) parameters on the microstructure and tensile property of SLM-formed Ti-6Al-4V titanium alloy were investigated. The results show that HIP performed below the β-phase transition temperature, and the structure of the Ti-6Al-4V titanium alloy is composed of an α phase and β phase. With the increase in the HIP temperature, the α lath coarsens into a short rod, the content of the β phase increases and coarsens, and the tensile strength and yield strength of Ti-6Al-4V show a decreasing trend. With an HIP process performed at a temperature of 910 °C and pressure of 130 MPa for 2 h, the Ti-6Al-4V titanium alloy obtains the best matching of strength and plasticity.

Study on fabrication of metallic Titanium from secondary Titanium slag of Binh Dinh titanium minerals using magnesiothermic reduction method

Titanium and its alloys are used in aviation, marine, medical, chemical and other fields because of their superior properties, such as low density, good corrosion resistance, high strength and biocompatibility. This paper presented a study on the possibility of producing metal titanium from secondary titanium slag by magnesiothermic reduction. The prepared products were characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and electron microscopy (SEM). The research results show that the magnesiothermic reduction method is capable of producing Ti metal directly from the secondary titanium slag with high recovery efficient. The resulting product is high-purity porous titanium, with a titanium content of up to 94,68% (without unfavourable impurities). The properties of Ti meet the requirements for the production of high-quality titanium alloys.

ТЕХНОЛОГІЧНІ ОСОБЛИВОСТІ ОДЕРЖАННЯ СПЛАВІВ ТА ЛІГАТУР СИСТЕМИ TI–ZR–NB–SN В УМОВАХ ЕЛЕКТРОННО-ПРОМЕНЕВОЇ ЛИВАРНОЇ ТЕХНОЛОГІЇ

Electron beam casting technology is a unique method for obtaining cast products and semi-finished products from a wide range of titanium alloys. This technology can be very promissing in production of biocompatible titanium alloys for endoprosthesis. A particularly difficult and important task in this context is preparation of Ti-Zr-Nb-Sn system alloys with high strength and low modulus of elasticity. As a result of experimental development of specified alloys melt preparation technological modes, possibility of obtaining complex titanium alloys with a high content of zirconium and niobium was shown. It is also determined, that when the niobium content in the charge is more than 30 % wt. there is a decrease in the concentration of titanium and zirconium in the melt due to their freezing on the walls of the skull. As a result, there is a change in the chemical composition of the melt, the amount of niobium in which can exceed 50 % wt. Maximum amount of tin that can be assimilated in titanium-based melts under EBCT conditions is 5 % wt., and niobium-based melts are twice less. It has been proven that obtaining melts of Ti-Zr-Nb-Sn system with a precise chemical composition, using the chosen method, is a difficult and still unsolved problem, but due to the possibility of melting alloys with a high content of niobium and zirconium in its conditions, this method is effective in the production of master alloys and ingots for the production of powders used as raw materials for additive tmanufacturing. Keywords: titanium alloys for endoprosthesis, foundry production, Ti-Zr-Nb-Sn, electron-beam casting technology.

One-step production of high-strength titanium alloy by sintering titanium hydride powder from upgraded titania slag

A direct production method of high-strength titanium alloy from upgraded titania slag (UGS) was developed. First, UGS was reduced into alloy powder with 1.3 wt.% oxygen using magnesium powder. Subsequently, the alloy powder was compacted at 600 MPa to produce a pellet. Lastly, the pellet was sintered to produce titanium alloy. The reduced powder was characterized, and the effect arising from the sintering temperature on the sintered density, compressive strength, microstructure, and hardness of the alloys was studied. The results showed that the density tended to increase with the temperature increasing from 900 to 1200 °C, whereas the porosity decreased. A significant sintering densification was achieved at the temperature above 1100 °C (98.65% at 1100 °C and 99.41% at 1200 °C). At 1100 °C, the hardness and compressive strength reached the maximal values of the alloy, HV 655.7 and 1563 MPa, respectively.

Optimization of Multi-Track Laser-Cladding Process of Titanium Alloy Based on RSM and NSGA-II Algorithm

Titanium alloy is an important material in the 21st century and its consumption in the aerospace and energy fields is increasing. In the production and repair of titanium alloy, the problem of energy saving and consumption reduction is becoming increasingly important. Laser-cladding technology with optimized parameters can bring great economic benefit. In order to obtain the best process parameters of laser-cladding TC4 alloy powder, a method of laser-cladding parameters’ optimization based on the RSM and NSGA-II Algorithm is proposed. The BBD (Box–Behnken Design) experiment scheme was designed by the response surface method. A surrogate model between input variables (laser power, scanning speed, and powder-feeding speed) and response values (macroscopic quality, microhardness, and average friction coefficient) was established. The second generation non-dominant sorting genetic algorithm (NSGA-II) was used to optimize the process parameters and the optimization results were verified by experiments. The results show that the optimum parameters are a laser power of 2600 W, scanning speed of 19.1 mm/s, and powder-feeding rate of 12.2 g/min. The samples prepared with the best process parameters show mainly abrasive wear, accompanied by a small amount of adhesive wear. Its wear depth is 7.71 μm and the average friction coefficient is 0.293. After cladding, the macroscopic quality of the cladding layer is increased by 5.8%, the microhardness is increased by 10.1%, and the average friction coefficient is reduced by 27.6%.

Effect of fibre laser welding parameters on the microstructure and weld geometry of commercially pure titanium

The primary purpose of the study was the metallurgical characterization of laser welds. The weldability of commercial production of pure titanium and titanium alloy (CP-Ti) has also been examined. In this research, the laser fibre method was used to weld sheets of pure titanium, and then microscopy and scanning electron microscopy were used to study the changes in the microstructure, the depth of weld penetration and the width of the weld area with changing welding parameters. The results proved that increasing the laser power significantly increases the depth of weld penetration and weld width. When the heat input is increased, the shape of the weld pool changes from a V shape to an hourglass shape. It was also observed that the depth of the crater formed increases with the increase in the laser power due to the increase in the melting and evaporation of the weld metal. Increasing the welding speed also has a negative impact on the weld geometry because it reduces the heat input and absorption of laser energy by the weld metal and thus reduces the melting of the metal. The microstructure of the fusion zone consists of acicular α. Fine grains formed in the weld centre at low heat input; the granules became columnar-like. Since commercially pure titanium contains a small amount of beta-phase stabilizers, the cooling rate is extremely high for martensite to occur. In the future, it is recommended to study the effect of changing welding parameters on the mechanical properties of pure titanium because of its great importance in industrial and medical applications. Studying the effect of changing laser power and welding speed on the metallurgical properties of pure titanium, and consequently its effect on the mechanical properties of welds.

Green Forging of Titanium and Titanium Alloys by Using the Carbon Supersaturated SKD11 Dies

The carbon-supersaturated SKD11 punch was proposed as a green, or, a galling-free, long-life and low energy-consuming forging tool of pure titanium and β-titanium alloy that works with low friction and less work hardening and without galling. The reduction in thickness was increased up to 50% to investigate the friction process on the contact interface and the work-hardening behavior. The nitrogen-supersaturated SKD11 punch was utilized as a reference tool for this forging experiment. Three-dimensional finite element analysis was employed to derive the regression curve between the contact interface width and the friction coefficient. The friction coefficient was estimated in forging the pure titanium wires by using the regression curves. The work-hardening process was analyzed by the hardness mapping on the cross-section of forged wires. The SEM-EDX analysis on the contact interface proved that no adhesion of fresh metallic titanium and titanium oxide debris was seen on the interface between the carbon-supersaturated SKD11 punch and the titanium work. In particular, the work hardening is suppressed without shear localization in forging the β-titanium. Finally, the uniform carbon layer was derived from the supersaturated carbon solute from the punch matrix and wrought as a friction film on the contact interface to reduce the friction and the work hardening as well as suppress the chemical galling. This in situ carbon lubrication must be essential in green forging to highly qualify the titanium and titanium alloy products and to prolong the punch-and-die lives in practical operation.

Production and characterization of titanium based metal matrix composites: a review

Titanium alloys are regarded as high strength and lowdensity alloys. It has wide range of applications such as in biomedical and automobile because of its high strength, low density, biocompatibility and good corrosion resistance. Titanium alloys can be produced by adding elements like aluminium, vanadium, molybdenum, zirconium etc. The powder metallurgy method is widely used method for production of titanium alloys because of its low cost of production. In this study, Ti6Al4V based composites synthesized by adding various reinforcements through powder metallurgy method are considered and the results from these studies are reported.

Research status and prospect of ceramic crucibles for induction melting of titanium alloys

<p indent="0mm">Titanium alloys possess high specific strength, superior heat resistance, excellent corrosion resistance, outstanding physiological compatibility, etc., and thus being considered as the most ideal lightweight structural materials as well as potent biomedical materials. Generally, Ti alloys are manufactured via the technique of ingot metallurgy; however, it suffers from critical issues of high energy consumption and high cost, which desperately need to be well addressed. According to previous research, the crucible vacuum induction melting technology has high superheat and strong electromagnetic stirring, with which titanium alloy ingots with uniform composition can be achieved without applying multiple remelting. The crucible vacuum induction melting not only benefits the removal of low melting point impurities, but also significantly improves the energy consumption efficiency as the forced water cooling becomes not indispensable during the processing. As a result, the crucible vacuum induction melting has been the most potential method to overcome the problems of high energy consumption and low material yield existed in conventional melting technology. However, titanium alloys can react with almost all the refractories because of their high chemical activity, resulting in the pollution of titanium ingot and thus seriously restricting the development and application of this technology in titanium alloy production. For this reason, preparation special crucibles with corrosion resistance to titanium liquid is crucial to realizing low-cost, high-quality, and high-efficiency smelting of titanium alloys. Herein, we provide a comprehensive review of the research status of ceramic crucibles for titanium alloys including the selection of materials (thermodynamic criterion, corrosion resistance mechanism, composition optimization) and the promising processes to improve the durability of these crucibles. Usually, the thermodynamic criterion is used as the first-step to pick ceramic materials with high chemical stability, which involves a comparison of the free energies of formation of ceramic materials with their corresponding titanium compounds. It is necessary to further evaluate the interface reaction mechanism between candidate ceramic materials and titanium melts under induction melting conditions to compensate for the neglect of disregarding physical and chemical erosion in thermodynamic approach. Based on a systematically comparison of the interface reaction mechanism between titanium melts and various common refractory materials involving oxide ceramics (Y₂O₃ and CaO), zirconate ceramics (BaZrO₃ and (Ca,Sr,Ba)ZrO₃) and non-oxide ceramics, AlN and TiN show promising properties for melting titanium alloys due to their relatively smaller oxygen contamination. In addition to corrosion resistance of ceramics against titanium melts, the thermal shock resistance is the other critical criterion to realize a long service life of the crucibles under repeated induction melting conditions. Scholars attempted many methods, such as porosity optimization, doping modification, surface coating, to solve the imbalance between the corrosion resistance of titanium liquid and thermal shock resistance of materials. Currently, the crucibles can only be prepared at laboratory size, how to realize the production of large-size crucibles with balancing the cost, corrosion resistance and thermal shock resistance is full of serious challenges. On the basis of the recent research progress of Huazhong University of Science and Technology, innovative thinking in terms of the future development of ceramic crucibles for titanium alloy induction melting is suggested: (1) the optimization of refractories: how to reap the advantages of computer technology to speed up the development of new crucible materials; (2) higher demands for thermal shock resistance and high temperature strength: figuring out the relationship between the preparation parameters and the surface quality of the crucibles; (3) the preparation of the special crucibles with large size, high durability: addition of ultra-high temperature reinforcements being a promising route for the fabrication of industrial grade crucibles for titanium alloys induction melting.