Structure Of Titanium Alloys Research Articles

Influence of Quenching Temperature on the Structure, Phase Composition, Physical and Mechanical Properties of a High-Strength Titanium Alloy of the Martensitic Class

Influence of Quenching Temperature on the Structure, Phase Composition, Physical and Mechanical Properties of a High-Strength Titanium Alloy of the Martensitic Class

Contour Detection Algorithm for α Phase Structure of TB6 Titanium Alloy fused with Multi-Scale Fretting Features

Aiming at the problems of inaccuracy in detecting the α phase contour of TB6 titanium alloy. By combining computer vision technology with human vision mechanisms, the spatial characteristics of the α phase can be simulated to obtain the contour accurately. Therefore, an algorithm for α phase contour detection of TB6 titanium alloy fused with multi-scale fretting features is proposed. Firstly, through the response of the classical receptive field model based on fretting and the suppression of new non-classical receptive field model based on fretting, the information maps of the α phase contour of the TB6 titanium alloy at different scales are obtained; then the information map of the smallest scale contour is used as a benchmark, the neighborhood is constructed to judge the deviation of other scale contour information, and the corresponding weight value is calculated; finally, Gaussian function is used to weight and fuse the deviation information, and the contour detection result of TB6 titanium alloy α phase is obtained. In the Visual Studio 2013 environment, 484 metallographic images with different temperatures, strain rates, and magnifications were tested. The results show that the performance evaluation F value of the proposed algorithm is 0.915, which can effectively improve the accuracy of α phase contour detection of TB6 titanium alloy.

Investigating dwell fatigue crack growth in welded titanium alloy structures

ABSTRACT In this paper, dwell-fatigue crack growth tests under complex loading spectra were conducted for a titanium alloy used in marine structures. The influence of upper and lower peak dwell time on the dwell-fatigue crack growth behavior of the welded structure were comprehensively investigated. The results show that the longer the upper and lower peak dwell times were, the faster the crack growth rate was. Still, the impact of the upper and lower dwell times on the crack growth rate of titanium alloy had a specific saturation value. Based on the above findings, a new model was developed that combined the fracture mechanics theory, considering the effects of welding and load dwell on crack growth. By predicting the dwell-fatigue behavior of titanium alloy welded structures using the model, it was confirmed that the model has a strong prediction ability for the dwell-fatigue behavior of welded structures under complex loads..

Research on 3D printed titanium alloy scaffold structure induced osteogenesis: Mechanics and in vitro testing

Several methods exist for repairing mandibular segmental bone defects, typically employing the implant method to accomplish the repair. Following a comparative analysis, the Ti6Al4V structural scaffold implant was chosen for bone defect repair. Triply periodic minimal surface (TPMS) is characterized by a high surface area to volume ratio, an average curvature of zero, and other notable advantages, providing a new line of thinking for bone tissue scaffolds. In this work, the in vitro osteogenesis of a cell unit measuring 4 mm was investigated. First, the finite element analysis (FEA) method and the mechanical experiment method were employed to screen the elasticity modulus of the cancellous bone of the mandible. Subsequently, the selective laser melting (SLM) technique was adopted to prepare three different structures precisely - Gyroid, octahedron, and cube - each with wall thicknesses of 0.3 mm, 0.4 mm, and 0.5 mm. In the in vitro osteogenic experiments, it was observed through confocal laser scanning microscopy (CLSM) that each scaffold displayed favorable cell spreading at 1 day and 3 days. Moreover, osteoblast cell adhesion and proliferation assays revealed improved cell adhesion and proliferation with prolonged co-cultivation time, signifying the excellent biocompatibility of the structural titanium alloy scaffolds. Furthermore, findings from cell differentiation and bioactivity assays indicated that the Gyroid structure exhibited superior osteogenesis compared to the cube and octahedron structures. However, no statistically significant difference was noted between varying wall thicknesses within the same structure.

In-situ deformation mechanisms of a novel Ti-5Mo-4Cr-1V-1Zr metastable β titanium alloy

To overcome the strength-plasticity trade-off in the structural titanium alloys, a novel metastable β titanium alloy Ti-5Mo-4Cr-1V-1Zr (Ti-5411) with high strength and high plasticity was designed by the d-electrons theory, average electron-to-atom ratio (e/α‾) and atomic radius difference (Δr‾) theory. Combined in-situ scanning electron microscope (SEM) and electron backscatter diffraction (EBSD), the deformation mechanisms of the novel Ti-5411 metastable β titanium alloy were systematically investigated. The results show that the Ti-5411 alloy exhibits excellent yield strength (∼689 MPa), tensile strength (∼930 MPa) and total elongation (∼39%). The in-situ tension indicates that slip activities, crystal rotation, stress induced martensite (SIM) α″ transformation and {332}<113> deformation twin are the major deformation mechanisms of Ti-5411 alloy. Besides, with the increase of strain degree (0–0.5 mm displacement), deformation twins increase, widen and interlace. At 0.35 mm tensile displacement, the orientation of the β grains rotates ∼6.65° to accommodate the increased macrostrain. Additionally, martensite α″ also assists the nucleation of twins. Some {332}<113> twins grow and merge by consuming martensite α″ during deformation, and the residual martensite α″ remains in the merged twins.

The influence of rapid-diffusive β-stabilizers on the microstructure formation and superplasticity of titanium-based alloys

The superplasticity of Ti-based alloys is improved due to grain refinement, an increase in grain size stability, and an increase in the β-phase fraction up to ∼0.5. Alloying with β-stabilizers reduces the β-transus temperature and increases the β-phase fraction at low forming temperatures, thus improving the superplasticity and lowering its temperature. Both grain growth and superplastic deformation mechanisms are diffusion-controlled phenomena, and, therefore, the diffusivity of the alloying elements should have a significant effect on superplasticity. This work deals with the influence of the high-diffusive elements Fe, Co, and Ni on the grain structure and superplasticity of titanium alloys. For this purpose, the Ti-Al-Mo-V alloy, and alloys with proportional replacement of low-diffusive Mo by Fe, Co, or Ni, exhibiting an interstitial diffusion mechanism, were studied. The alloying elements content was selected to ensure the same β-phase fraction at a deformation temperature of ∼875 °C. The microstructure evolution after thermomechanical processing, annealing, and superplastic deformation, as well as post-deformation room-temperature mechanical properties of the studied alloys, were compared. The actual phase ratio was reconstructed by comparing scanning electron microscopy images in backscattered electrons and electron backscatter diffraction data for the same fragments. It was found that Mo replacement for highly diffusive elements accelerated dynamic grain growth during superplastic deformation at an elevated temperature of 875 °C but improved superplasticity at a lower temperature of 775 °C. The results confirmed that alloying with high-diffusive elements is a promising strategy for the design of low-temperature superplastic forming alloys.

Preparation of Ag@3D-TiO2 Scaffolds and Determination of its Antimicrobial Properties and Osteogenesis-promoting Ability.

The micro-nano structure of 3D-printed porous titanium (Ti) alloy with excellent performance in avoiding stress shielding and promoting bone tissue differentiation provides a new opportunity for the development of bone implants, but it necessitates higher requirements for bone tissue differentiation and the antibacterial properties of bone implants in clinical practice. This study investigated the preparation, antimicrobial properties, and osteogenesis-promoting ability of the 3D printed porous Ti alloy anodic oxidized Ag-carrying (Ag@3D-TiO2) scaffolds. The 3D printed porous Ti alloy (3D-Ti), anodized 3D printed porous Ti alloy (3D-TiO2), and Ag@3D-TiO2 scaffolds were synthesized using electron beam melting. The antimicrobial properties of the scaffolds were examined using antibacterial tests and their cytocompatibility was assessed using a cell proliferation assay and acridine orange/ethidium bromide (AO/EB) staining. In vitro cellular assays were used to investigate the effects of the scaffold microstructural features on cell activity, proliferation, and osteogenesis-related genes and proteins. In vivo animal experiments were used to evaluate the anti-inflammatory and osteogenesis-promoting abilities of the scaffolds. The Ag@3D-TiO2 scaffolds exhibited sustained anti-microbial activity over time, enhanced cell proliferation, facilitated osteogenic differentiation, and increased extracellular matrix mineralization. In addition, alkaline phosphatase (ALP), collagen type I (COL-I), and osteocalcin (OCN)-related genes and proteins were upregulated. In vivo animal implantation experiments, the anti-inflammatory effect of the Ag@3D-TiO2 scaffolds were observed using histology, and a large amount of fibrous connective tissue was present around it; the Ag@3D-TiO2 scaffolds were more bio-compatible with the surrounding tissues compared with 3D-Ti and 3D-TiO2; a large amount of uniformly distributed neoplastic bone tissue existed in their pores, and the chronic systemic toxicity test showed that the 3D-Ti, 3D-TiO2, and Ag@3D-TiO2 scaffolds are biologically safe. The goal of this study was to create a scaffold that exhibits antimicrobial properties and can aid bone growth, making it highly suitable for use in bone tissue engineering.

Effects of ion-plasma treatment temperature of the aluminium coating on the structure and phase composition of the VT6 titanium alloy

In this study, we studied the effects of aluminum coating treatment temperature on the microstructure and phase composition when applied to a VT6 titanium alloy substrate within a low-pressure arc discharge plasma environment. The ion-plasma treatment was conducted at 450 and 500 °C, employing argon shielding, while the aluminum coating was deposited using the vacuum-arc process, resulting in a coating thickness of ~3 μm. Microstructural analysis was performed using a scanning electron microscope, and the structural and phase composition were examined using X-ray diffraction (XRD) imaging in symmetric imaging mode with CuKα radiation. Our findings demonstrate that the application of the aluminum coating initiates the formation of a near-surface α-stabilized layer, extending up to 2.5 μm in thickness due to the heat generated during the ion cleaning process. Subsequent ion-plasma treatment further results in the development of a TiAl3 intermetallide site, reaching thicknesses of up to 1.5 μm, while the α-stabilized region expands to 5.5 μm. Higher temperatures during the treatment process contribute to an increase in the thickness of these aforementioned layers and also lead to the emergence of an intermediate TiAl intermetallic layer.

Microstructure and Mechanical Properties Ultrasonic Assistance Laser Welded Joints of Beta Titanium Alloy with Multiple Vibrators

Aiming at the problem of deterioration of the properties of beta titanium alloy welded joints due to many porosity defects and coarse grains, multi-vibrator ultrasonic-assisted laser welding (M—ULW) technology was used to improve the structure and properties of beta titanium alloy welded joints. The microstructure evolution, tensile strength, elongation, and fracture behavior of the weld joint were studied through scanning electron microscopy, electron back-scatter diffraction, and a universal testing machine. The results show that ultrasonic vibration has no effect on the phase composition of titanium alloy welds during ultrasonic-assisted laser welding. However, it caused all grains in the weld to be transformed into equiaxed grains, and the higher the amplitude, the finer and more uniformly distributed were the equiaxed grains. When the ultrasonic amplitude reached 20 μm, the fine equiaxed crystals were uniformly distributed throughout the weld, and the average grain size of the weld was 56.15 um, which is only one-third of that of the unultrasonicated laser welded joint. Ultrasonic refinement makes the joint grain size decrease, weakens the beta titanium alloy {200} direction weaving, increases the dislocation density within the weld; and increases the tensile strength of the welded joint. The tensile strength of the welded joints exceeded that of the base material by 907 MPa, and the elongation was significantly increased by a factor of 1.8 compared with that of the un-ultrasonicated laser welded joints, resulting in a shift of the fracture location from the center of the weld to the heat-affected zone.

Porous titanium alloys for medical application: Progress in preparation process and surface modification research

Excellent mechanical properties and biocompatibility are the most sought-after attributes in biomedical materials for the regeneration of damaged tissues. However, conventional dense titanium alloys possess a modulus significantly higher than that of human tissues, leading to potential stress-shielding effects. Medical porous titanium alloys can reduce the elastic modulus of the material, promote tissue fixation and vascular regeneration, and improve the suitability for human tissue properties. With the continuous development of technology, the preparation process of porous titanium alloys has undergone a series of multifaceted transformations and improvements in the aspects of powder sintering, fiber preparation, and additive manufacturing processes, and its structural characteristics and mechanical properties are constantly evolving in a controllable direction. Alongside the enhancement of the material&amp;rsquo;s mechanical properties through porous design, optimization of the properties at the implant-tissue interface also leads to improved antimicrobial and osteogenic properties of porous titanium. Due to the complex internal structure of porous titanium alloys, surface modification is mainly carried out in fluid media, which is realized by morphological modification and the introduction of functional substances. Over time, the surface modification of porous titanium alloys for medical applications has progressed from morphological modification and introduction of chemical composition to the loading of bioactive substances. This evolution aims to enhance safety and efficiency in the use of these materials. This paper reviews the preparation and surface modification processes of porous titanium alloys for medical use and summarizes the advantages, disadvantages, and influencing factors among different processes, with a view to providing new ideas for the development of porous implants for medical use.

Novel flat-top laser-aided cold metal transfer additive manufacturing for titanium alloy: Arc characteristics, microstructure, and tensile properties

In this paper, a novel flat-top laser-aided cold metal transfer additive manufacturing (F-LCAM) method is proposed for titanium alloys to restrict internal defects and anisotropy of mechanical properties in large-scale additive-manufactured titanium structures. The proposed method uses a flat-top laser to stabilise the drifting cathode spot and suppress the irregular shape of the weld deposit by promoting thermionic emission on the molten pool surface. Compared to the cold metal transfer additive manufacturing (CMT-AM) process, the auxiliary flat-top laser promotes the wettability of the molten pool and increases the contact angle of deposition from 95° to 142° in an F-LCAM sample. The non-destructive X-ray testing (NDT) results of multi-bead multilayer deposition showed that the defects caused by the pool weld bead morphology were effectively suppressed. Attributed to fluid flow in the melt pool enhanced by the flat-top laser, the dendritic arms were broken, columnar β grains in the F-LCAM sample were finer than in CMT-AM sample, and the aspect ratios of prior-β grains decreased from approximately 6 to 1. The F-LCAM sample exhibited a higher elongation and lower anisotropy than the CMT-AM sample. Defects were observed on the fracture surfaces of the CMT-AM vertical samples, which reduced the elongation of the CMT-AM samples to lower than that of the F-LCAM sample. The ultimate tensile strength, yield strength, and elongation of the multi-bead multilayer deposition met the standards of as-forged Ti6321 titanium alloy, indicating that the Ti6321 titanium alloy structure fabricated by the F-LCAM process has acceptable tensile properties for engineering applications.

Effect of process parameters on residual stresses in SLM-formed bionic porous titanium alloy structures

Bionic porous titanium alloy structures have demonstrated broad application prospects in the field of biomedicine, and selective laser melting (SLM) has become one of the main methods for preparing porous titanium alloy structures due to its high degree of forming freedom. Residual stress is a crucial indicator for evaluating the forming quality of SLM parts, thus its control methods have garnered significant attention. Therefore, it is important to understand the process parameters' influence on the generation and regulation of residual stresses in SLM-formed bionic porous titanium alloy parts. In this paper, finite elements and experiments are employed to research the relationship between process parameters and residual stresses in the SLM process, and a method for controlling residual stresses in the key sensitive areas is proposed. It is found that increasing the laser scanning speed is conducive to reducing the residual stress of the porous structure and alleviating the phenomenon of stress concentration. Appropriately increasing the laser power can reduce the residual stress in the Z direction of the porous structure, with the optimal range being from 200 W to 250 W. Using a medium laying powder thickness (0.03 mm∼0.04 mm) results in uniformly distributed residual stress on the surface of the porous structure, leading to the attainment of maximum residual compressive stress. Building upon this foundation, the experimental verification of forming quality established stability, while the derived parameter optimization method and forming mechanism offered theoretical support for process optimization in fabricating porous titanium alloy structures through SLM.

АСПЕКТЫ ПРИМЕНЕНИЯ ИНДЕКСНОЙ ОЦЕНКИ СОСТОЯНИЯ ОРГАНОВ И ТКАНЕЙ ПОЛОСТИ РТА У ПАЦИЕНТОВ С ОРТОПЕДИЧЕСКИМИ КОНСТРУКЦИЯМИ ИЗ КОНСТРУКЦИОННЫХ ТИТАНОВЫХ СПЛАВОВ

The study is aimed at assessing the impact of orthopedic structures made of titanium alloys on the condition of organs and tissues of the oral cavity in patients. This study presents the results of an index assessment of the studied parameters, materials and methods of research, as well as conclusions based on the results obtained. Hygienic indices were assessed in three groups of patients with various orthopedic structures, the groups were divided depending on the structural material of the orthopedic structure, the third group was a control group, before the start of treatment and sanitation of the oral cavity, as well as after sanitation procedures carried out a month and six months later. These procedures were mandatory, as 76% of patients were found to have high plaque content upon admission to the clinic. This plaque ranged from thin to moderately dense and was visible to the naked eye. In some cases, there was a significant accumulation of plaque in the interdental spaces and gingival furrows. In patients of the first and second groups, we also evaluated the hygienic indices a month and six months after orthopedic treatment using titanium alloy structures.

Achieving excellent fatigue crack growth resistance and tensile strength combination in multilayered TC4/TB8 structures

Here we report a multilayered TC4/TB8 titanium alloy structure fabricated by diffusion bonding that can produce an excellent property combination. Its fatigue crack growth (FCG) life increases by 6.2 times and 2.6 times compared to TB8 plate and TC4 plate, respectively. Meanwhile, the tensile ultimate strength reaches 1128 MPa, which is near high strength of TB8 alloy. The delamination at bonded interfaces and crack deflection within layers induced by different mechanical responses of both TC4 and TB8 alloys promote the FCG life improvement of multilayered TC4/TB8 structures. Besides, multilayered structures can obtain sufficient strength due to well-bonded joints and high-strength TB8 layers. The influence of dissimilar layers and interlayer cracking on the distribution of stress and strain fields at the crack tip was simulated using the Abaqus software.

Effect of process parameters on the corrosion kinetics and mechanism of nanosecond laser surface structured titanium alloy (Ti6Al4V)

In this study, laser surface structuring (LSS) of Ti6Al4V was carried out using an Nd:YLF laser with a second harmonic wavelength of 527 nm and a pulse duration of 100 ns at varied laser fluence, scan speed, and line spacing. A detailed study of the effect of process parameters on surface topography, microstructure, composition, phase, contact angle, electrochemical behavior, and bioactivity was undertaken. Nanosecond pulsed laser irradiation with overlapping resulted in the formation of linear continuous grooves on the surface due to ablation/evaporation of materials. There is the formation of oxides of titanium (TiO2 and Ti2O3) whose mass fractions varied with process parameters. The average microhardness of the laser-structured region was improved (393 VHN - 535 VHN) as compared to the as-received Ti6Al4V (303 VHN). The contact angle of simulated body fluid (SBF) against the structured surface (58°- 123°) showed increased contact angle as compared to as-received samples (50°). The laser surface structuring exhibited a superior corrosion resistance property (in SBF) as compared to as-received Ti6Al4V. The mechanism of corrosion behavior was established by electrochemical impedance spectroscopic study (in SBF). The optimum process parameter for the LSS of Ti6Al4V with enhanced hardness and corrosion resistance was derived. The LSS surface processed under the optimum parameters measured by immersing in SBF revealed a higher deposition of calcium phosphate as compared to the as-received Ti6Al4V.

CREEP OF VT1-0 TITANIUM ALLOY IN DIFFERENT STRUCTURE STATES AFTER IRRADIATION WITH HELIUM IONS

The effect of irradiation with helium ions at T = 350°C with an energy of 20 keV and a dose of 1.5·1018 Не/cm2 on the structure and properties of VT1-0 titanium alloy in the initial and nanostructural states was studied. It has been shown that irradiation of VT1-0 samples in the initial state leads to a decrease in mechanical properties when tested under creep conditions at T = 350 °C, which may be due to dynamic recovery. A material in a nanostructured state is characterized by an increase in strength and creep rate at a test temperature of T = 350°C, while maintaining a plasticity reserve. The effect is associated with the structure rearrangement, grain growth and the development of strain hardening processes as the effective stress increases.

Overview of Surface Modification Techniques for Titanium Alloys in Modern Material Science: A Comprehensive Analysis

Titanium alloys are acclaimed for their remarkable biocompatibility, high specific strength, excellent corrosion resistance, and stable performance in high and low temperatures. These characteristics render them invaluable in a multitude of sectors, including biomedicine, shipbuilding, aerospace, and daily life. According to the different phases, the alloys can be broadly categorized into α-titanium and β-titanium, and these alloys demonstrate unique properties shaped by their respective phases. The hexagonal close-packed structure of α-titanium alloys is notably associated with superior high-temperature creep resistance but limited plasticity. Conversely, the body-centered cubic structure of β-titanium alloys contributes to enhanced slip and greater plasticity. To optimize these alloys for specific industrial applications, alloy strengthening is often necessary to meet diverse environmental and operational demands. The impact of various processing techniques on the microstructure and metal characteristics of titanium alloys is reviewed and discussed in this research. This article systematically analyzes the effects of machining, shot peening, and surface heat treatment methods, including surface quenching, carburizing, and nitriding, on the structure and characteristics of titanium alloys. This research is arranged and categorized into three categories based on the methods of processing and treatment: general heat treatment, thermochemical treatment, and machining. The results of a large number of studies show that surface treatment can significantly improve the hardness and friction mechanical properties of titanium alloys. At present, a single treatment method is often insufficient. Therefore, composite treatment methods combining multiple treatment techniques are expected to be more widely used in the future. The authors provide an overview of titanium alloy modification methods in recent years with the aim of assisting and promoting further research in the very important and promising direction of multi-technology composite treatment.

Study of structure and properties of titanium alloy manufactured by selective electron beam melting using "thin walls" mode

The results of research on the powder from the titanium alloy Ti—6Al—4V, used for selective electron beam melting, are presented. The study reveals the structure and mechanical properties of standard thin samples made from the titanium alloy Ti—6Al—4V using the developed ‘thin walls’ mode. It has been established that the alloy structure obtained through the "thin walls" mode exhibits a Widmansttten structure with low dispersion of α-phase plates. The manufactured samples demonstrate higher strength compared to samples produced using traditional technology.

Research of Superplastic Forming, Mechanical Properties, and Thermal Insulation Performance of Titanium Alloy 3D Lattice Structure

A physically constitutive model based on microstructure evolution was constructed to describe the coupling relationship between various macro and micro variations of TA32 titanium alloy in superplastic deformation. Then, a finite element analysis model was established to simulate and analyse the superplastic forming process of titanium alloy based on the physically constitutive model. The deformation characteristics, mechanical properties and thermal insulation performance of the three dimensional lattice structure were analysed and tested. The results show that the three-dimensional lattice structure of titanium alloy has good formability, excellent mechanical properties, and good thermal insulation performance, indicating that it is a promising load-bearing functional integrated structure.

Модуль упругости и твердость титанового сплава, сформировавшегося в условиях электронного лучевого сплавления при 3D-печати проволокой

Introduction. The development and application of additive manufacturing depends on many factors, including the printing process performance and buy-to-fly ratio. Wire-feed electron-beam additive manufacturing (EBAM) is attracting more and more attention from research teams. Moreover, the use of electron beams is the most effective and competitive for additive manufacturing of parts from alloys possessing high oxidation characteristics, e.g., titanium, stainless steels, since selective laser melting occurs in vacuum. Welding titanium wire VT6sv is the most preferable choice due to its availability and a wide range of thickness. This alloy, however, has fewer alloying elements than VT6 (Ti–6Al–4V) alloys. The high performance of wire-feed 3D printing and the VT6sv alloy composition affect the structure, phase composition, and properties of the fabricated alloy. As is known, the elastic modulus and hardness of alloys are important parameters, which can be measured rapidly also using non-destructive testing. The purpose of this work is to study the application of different approaches to measuring the elastic modulus and hardness of products obtained by wire-feed EBAM using the equipment of the Institute of Strength Physics and Materials Science SB RAS. Research methods. The structure of VT6sv titanium alloys fabricated by 3D printing and VT1-0 (Grade 2), VT6 (Ti–6Al–4V) alloys, was investigated by different methods such as metallography, ultrasonic gauging, instrumented indentation technique, macro- and micro-indentation, indentation hardness testing. Results and Discussion. Titanium alloy fabricated from VT6sv titanium wire under different thermal conditions has a typical columnar structure throughout the forging height. The structure formation determines the elastic modulus and hardness at various points of the forging. It is found that the elastic modulus is higher than that of as-delivered Ti–6Al–4V alloys, while the hardness is lower. Micro-indentation shows lower values of the elastic modulus than macro-indentation, which approach to values obtained by ultrasonic gauging and in other works. Different values of the elastic modulus at different points of the 3D printed forging indicate its sensitivity to the structure and phase composition of the material and demonstrate capabilities of measuring techniques used in this work.