Ti 10V Research Articles

Asymmetry of microstructure and mechanical characteristics in metastable Ti–10V–2Fe–3Al alloy under tension and compression

Asymmetry of microstructure and mechanical characteristics in metastable Ti–10V–2Fe–3Al alloy under tension and compression

Grain refinement mechanism in adiabatic shear band of solution treated Ti–10V–2Fe–3Al alloy under high strain rate

The grain refinement mechanism in the adiabatic shear band (ASB) of solution treated Ti–10V–2Fe–3Al alloy was investigated under high strain rates using a split Hopkinson pressure bar and hat-shaped specimens. The TEM results show that elongated and parallel grains are the major characteristics of the transition region between the matrix and the centre of the ASB. The central region of the ASB consists of ultrafine and equiaxed recrystallized grains with a typical size of 100 nm. According to the classical one-dimensional Fourier heat conduction equation and recrystallization theory calculations, it is proved that ultrafine and equiaxed recrystallized grains did not undergo significant growth during the cooling stage after deformation. The thermodynamics and kinetics calculated results indicate that instant grain refinement within the ASB is due to the rotational dynamic recrystallization (RDR) that occurs during the deformation process.

Thermal deformation behavior investigation of Ti–10V–5Al-2.5fe-0.1B titanium alloy based on phenomenological constitutive models and a machine learning method

The two-phase titanium alloy Ti–10 V–5Al-2.5Fe-0.1 B was taken as the experimental material, and thermal compression experiments were carried out at a deformation temperature of 770–920 °C and a strain rate of 0.0005–0.5 s−1. An Arrhenius model, a modified Johnson-Cook model, and an improved BP neural network model based on the sparrow search algorithm (SSA-BP) model were established to predict the high temperature rheological stress of the alloy. A comparison of the prediction accuracy of the three models was made. When the partial random data in the rheological curves was used for model building and relatively independent data were used for predicting the rheological stress, the SSA-BP model had higher prediction accuracy, which exhibits the highest mean square correlation coefficient (R2) value of 0.9992 and the lowest root mean square error (RMSE) and average absolute relative error (AARE) values of 1.3031, and 2.0947 %, respectively. The ability of three models to predict the rheological stress for the new process parameters was verified. Results show that the SSA-BP model still has better prediction ability, which exhibits the highest mean square correlation coefficient (R2) value of 0.9720 and the lowest root mean square error (RMSE) and average absolute relative error (AARE) values of 5.0099, and 6.0382 %, respectively. The predicted values of SSA-BP for the rheological stress were used to construct the hot processing map. Results show that the trend of the power dissipation factor (η) value from the hot processing map predicted by SSA-BP can well agree with the microstructure evolution of the alloy.

The Decomposition of the Metastable Beta Phase in High-Strength Titanium Alloys VST5553, Ti–10V–2Fe–3Al, and BETA-21S

The Decomposition of the Metastable Beta Phase in High-Strength Titanium Alloys VST5553, Ti–10V–2Fe–3Al, and BETA-21S

Control of the Electrode Gap during VAR of Ti–10V–2Fe–3Al Alloy Ingots Using Reversed Polarity Pulses

Control of the Electrode Gap during VAR of Ti–10V–2Fe–3Al Alloy Ingots Using Reversed Polarity Pulses

Revealing the martensitic variant selection in metastable beta titanium alloy Ti–10V–2Fe–3Al under heterogeneous deformation

As an important deformation mode for the mechanical responses of titanium (Ti) alloys, the martensitic transformation has earned enormous interest, for example, the variant selection, under macro uniaxial stress by tension or compression. However, the variant selection under small-scale deformation with a complex loading condition was rarely reported. In the present study, the small-scale deformation of metastable beta Ti alloy was investigated using nanoindentation combined with the transmission electron microscope (TEM) observation. Different martensitic variants were detected under the complex strain/stress field given by the indenter in the single titanium crystal, which was well interpreted by the Schmid factor (SF) and interaction work (IW) criterion, with the assistance of finite element (FE) simulation. The same prediction given by SF and IW comes from the truth that SF for simple shear is a special case of the IW criterion.

Microstructure and tensile properties of a multi-alloyed α + β titanium alloy Ti4.5Al10.5V3Fe

Based on the thermodynamic database of the Ti–Al–Fe–V quaternary system, a novel α + β titanium alloy, Ti-4.5Al-10.5V–3Fe, with greater performance was developed by combining CALPHAD and Mo equivalent method. The microstructure shows that this alloy is composed of α and β phases in both rolled and heat treatment states, which is in line with the theoretical expectation. The tensile properties of this alloy were tested at room temperature, and the tensile strength (σb) and elongation (EI) achieved 1085.1 MPa and 15.5%, respectively. Compared with Ti-1023 alloy (Ti–10V–2Fe–3Al), the developed Ti-4.5Al-10.5V–3Fe alloy has better properties. The fracture morphology was analyzed and the results show that the alloy is plastic fracture. The Ti-4.5Al-10.5V–3Fe alloy shows promising potential application prospects although more research is needed to further understanding this alloy. These results also provide theoretical support for further development of titanium alloys containing Al, Fe and V.

Role of surface structures on long term stability of adhesive joints between Ti–15V–3Cr–3Sn–3Al and polyether-ether-ketone

Adhesive bonding of similar and dissimilar materials is a key enabler for lightweight design in the automobile as well as aerospace industries. The strength and durability of adhesive metal-polymer joints in humid atmospheres depends strongly on surface pretreatments. Different pretreatments of Ti–15V–3Cr–3Sn–3Al (Ti15-3) for joining to polyether-ether-ketone (PEEK) were investigated in order to optimize the joint properties and elucidate underlying bonding mechanisms. Micro- and nanostructured surfaces were created with laser and chemical pretreatments and characterized with microscopy and X-ray photoelectron spectroscopy (XPS). The mechanical performance of the joints was analyzed with single lap shear tests in both the initial condition and after hydrothermal aging. Without significant structuring only physico-chemical interactions were present that accounted for strengths of up to 45 MPa. In the presence of micro- or nanostructures that add interlocking possibilities to the bonding, a maximum strength of 74 MPa was obtained. Hydrothermal aging resulted in poor residual strengths for samples without structuring, showing that humidity strongly degraded physico-chemical bonding. High aging resistance was particularly reached for laser pretreated specimens with an open-porous nanostructure. By comparing the different surfaces, it was found that (i) nanostructuring has a bigger impact on the aging resistance than microstructuring, and (ii) aging can be assigned mainly to weakening of physico-chemical bonding. Therefore, it can be deduced that nanomechanical interlocking is a key for producing long-term stable Ti15-3/PEEK joints.

Integrated multi-scale modeling of variant selection during stress-induced martensite formation in metastable β Ti-alloys

Stress-induced martensite formation is the predominant mechanism during the deformation of various functional and structural Ti- alloys. To predict the performance of these alloys, stress-induced martensite formation was modeled as a function of crystal orientation and stress state. We present an integrated micromechanical modeling approach using finite element (FE) analysis and an elastic spectral solver based on Fast Fourier Transforms (EFFT), which allows direct correlation of the available work from martensite formation under complex stress-states in an in-situ characterized microstructure. The model is applied as a virtual analogue of an experimental 3-point bending test of a metastable β Ti–10V–2Fe–3Al alloy containing 5% α. The FE model incorporates the experimental β microstructure from electron backscattering diffraction (EBSD) with anisotropic elastic behavior. The EFFT solver uses strain fields in two local regions from the FE model to predict local stresses in experimental microstructures containing β and α phases. The stress and orientation data are used to predict the available work from stress-induced α″ martensite formation of the six different α″ variants. It was found that stress and available work concentrated around the tips of lamellar α, making these regions preferred nucleation sites for α″ formation, which is in excellent agreement with the in-situ experimental observations. This suggests that the local stress conditions in the β phase play a more important role in triggering α″ formation than the compositional inhomogeneity in the β phase at α-β interfaces. Using the integrated model, the first variants forming at low levels of deformation could be confidently predicted. However, the transformation behavior at elevated levels of deformation could not be properly captured. This indicates the need of further model improvement, including Dirichlet boundary conditions for the EFFT solver and accounting for the role of plasticity induced by phase transformation.

The Effects Produced by the Rate of Heating on the Aging Temperature on the Structure and Hardening of the Ti–10V–2Fe–3Al Titanium Alloy with Different Carbon Contents

The Effects Produced by the Rate of Heating on the Aging Temperature on the Structure and Hardening of the Ti–10V–2Fe–3Al Titanium Alloy with Different Carbon Contents

Research on High-Temperature Compressive Properties of Ti–10V–1Fe–3Al Alloy

To investigate the thermal deformation behavior of Ti–10V–2Cr–3Al titanium alloy, the hot compression experiments were carried out via a strain rate of 0.1–0.001 s−1 and deformation temperature of 730~880 °C. The results showed that the rheological stress decreases when the deformation temperature increases or strain rate decreases. Due to the deformation conditions, some flow curves exhibited significant discontinuous yielding and flow softening. Flow softening in the α+β phase region was dominated by dynamic recrystallization (DRX), while in the β phase region, it was centered on dynamic recovery (DRV). A high-temperature constitutive equation, with good predictive power, was established.

Mechanical behavior and microstructural evolution during cyclic tensile loading-unloading deformation in metastable Ti–10V–2Fe–3Al alloy

The mechanical behavior and microstructural evolution for Ti–10V–2Fe–3Al (Ti-1023) alloy with a single metastable β-grains obtained by β solution treatment (β-ST) were discussed by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) during the various early stages of cyclic tensile loading-unloading deformation (abbreviated as cyclic deformation) at ambient temperature. The main deformation product is stress-induced martensite transformation (SIMT) by coupling mechanical characterization and microstructure observation. With the cycles increasing, the trigger stress of SIMT (σSIMT) decreases with a stress plateau (120 MPa ±10), and the volume fraction of SIMT gradually increases until a nearly complete α″ martensite microstructure. Besides, the deformation-induced martensite twins (DIMT) in the α″ martensite have been generated until reaching a certain strain value. Moreover, there is specific orientation relationships (SORs) between β matrix and α″ martensite with <100>β//<100>α″, <110>β//<010>α″, and <110>β//<001>α″. And the geometrically necessary dislocations (GNDs) structure evolution is sensitive to cyclic strain and grain orientation. Moreover, GNDs synergizes the microstructure evolution and mechanical behavior.

Effect of α phase fraction on the dynamic mechanical behavior of a dual-phase metastable β titanium alloy Ti–10V–2Fe–3Al

Dynamic mechanical behavior of a metastable β titanium alloy Ti–10V–2Fe–3Al (Ti-1023) with α+β dual-phase structure is investigated by a split Hopkinson tension bar (SHTB) system at two high strain rates of 2000 s −1 and 4000 s −1 . α phase fraction in Ti-1023 alloy is tuned via different heat treatments. Dynamic tensile stress-strain curves, deformation mechanisms and fracture are discussed in detail. As α phase fraction decreases from 60.5% to 4.5%, there is a transition from one-stage to three-stage work hardening, as well as a transition from single-to double-yielding phenomenon, which is caused by stress-induced martensitic transformation (SIMT). Positive strain rate effects are found on yield strength, ultimate tensile strength and triggering stress, while negative strain rate effect is found on uniform elongation of dual-phase Ti-1023 alloy. The connections between deformation mechanisms (including SIMT, hierarchical α" martensite structures, kinking and dislocation slip) and dynamic mechanical properties are discussed in detail. No adiabatic shear bands are found in the solution-treated alloys under SHTB loading.

Significant enhancement in yield strength for a metastable beta titanium alloy by selective laser melting

A β titanium alloy, Ti–10V–2Fe–3Al, was processed by pulsed selective laser melting. The as-fabricated sample was dominated by fibre-like columnar β grains and cellular structures which were embedded with a high density of nano-sized ω precipitates and dislocations. The samples demonstrated extraordinarily high yield strength (920–950 MPa) and high elongation (10–14%). After yielding, the samples showed nearly constant true stresses but changeable work hardening rates. Electron backscattered diffraction and transmission electron microscopy study on the deformed samples revealed that dislocation slipping has been the dominant deformation mechanism during tensile testing, which was accompanied by β→α′ martensitic transformation. The significantly high yield strength is attributed to the suppression of β→α′′ transformation and the fine grain and cell structures together with massive pre-existing dislocations. The abnormal increase in work hardening rate between 2.2% and 6% true strain is mainly attributed to the increased occurrence of stress induced β → α′ martensitic transformation.

A novel and high-strength Ti–Al–V–Fe alloy prepared by spark plasma sintering

ABSTRACT Ti–1Al–8V–5Fe (Ti-185) is a unique low-cost β-Ti alloy, containing lower cost alloying elements, notably Fe, as compared to Ti–10V–2Fe–3Al (Ti-1023) and Ti–5Al–5V–5Mo–3Cr (Ti-5553) while offering high strength. However, with higher Fe content (>5 at.-%), the ‘β-flecks’ are prone to form because strong segregation in traditional casting, which seriously deteriorates the mechanical properties of the alloys. In this work, Spark plasma sintering (SPS) was successfully used to produce Ti-185 components starting from elemental Ti and Al powders, and a V–Fe master alloy powder with different particle size (106, 45, and 23 μm). SPS can be used to produce a very fine grain microstructure with decreasing particle size master alloy powder and non-detrimental Fe segregation, and which result in a significant improvement of the mechanical properties. As the particle size of the FeV80 powder decreases, the compressive strength, yield strength and compressive strain of the alloy gradually increase.

Evolution of the Structure–Phase State of Quenched Ti–10V–2Fe–3Al Alloy during Aging

The evolution of the structure, phase composition, and hardness of quenched Ti–10V–2Fe–3Al titanium alloy during aging at a temperature of 500°C has been studied using scanning electron microscopy, X-ray diffraction, and hardness measurements. The variations in the lattice parameters of primary and secondary α-phases during aging of the alloy have been analyzed for the first time by X-ray diffraction using the profile analysis method. The results demonstrate that the expected redistribution of the alloying elements between the phases during aging has a systematic effect on the variation in their lattice parameters. We have evaluated the kinetics of the variation in the particle size of the secondary α-phase during aging.

High-Temperature Dry Sliding Wear Behavior of Ti–10V–2Fe–3Al

AbstractIn this study, the microstructure, high-temperature tribological performance, and mechanical properties of solution-aged Ti–10V–2Fe–3Al were investigated. The microstructure of solution-aged Ti–10V–2Fe–3Al reveals a bimodal α and β microstructure with uniformly dispersed α precipitates in the β matrix phase. The hot tribological performance of solution-aged Ti–10V–2Fe–3Al was investigated at different temperatures (28, 250, 350, and 450 °C) in a high-temperature pin-on-disc configuration. The wear mechanisms were evaluated at the worn-out surface using a scanning electron microscope (SEM). The abrasive wear mechanism is predominant at 28 °C and 250 °C testing conditions, whereas the oxidation and delamination are dominant wear mechanisms at 350 °C and 450 °C testing conditions. The worn-out surface at different temperature conditions was characterized by X-ray diffraction (XRD) and energy-dispersive X-ray spectrometer (EDS) analysis. The absence of protective oxide formation at 28 °C and intermittent protective oxide formation at 250 °C testing condition are ineffective in protecting the surface from wear damages and high wear loss. The protective tribo-oxide formations at 350 °C and 450 °C are continuous and provide improved wear resistance behavior of the material. The V2O5-rich tribo-oxide layer formation at 350 °C offers excellent wear resistance and protection against wear damages among the testing conditions. The Vickers microhardness study of the samples tested at different temperature conditions shows significant differences in the hardness magnitude at the cross section.

Estimating single-crystal elastic constants of polycrystalline β metastable titanium alloy: A Bayesian inference analysis based on high energy X-ray diffraction and micromechanical modeling

A two-phase near-β titanium alloy (Ti–10V–2Fe–3Al, or Ti-1023) in its as-forged state is employed to illustrate the feasibility of a Bayesian framework to identify single-crystal elastic constants (SEC). High Energy X-ray diffraction (HE-XRD) obtained at the Diamond synchrotron source are used to characterize the evolution of lattice strains for various grain orientations during in situ specimen loading in the elastic regime. On the other hand, specimen behavior and grain deformation are estimated using the elastic self-consistent (ELSC) homogenization scheme. The XRD data and micromechanical modelling are revisited with a Bayesian framework. The effect of different material parameters (crystallographic and morphological textures, phase volume fraction) of the micromechanical model and the biases introduced by the XRD data on the identification of the SEC of the β phase are systematically investigated. In this respect, all the three cubic elastic constants of the β phase (C11β,C12β,C44β) in the Ti-1023 alloy have been derived with their uncertainties. The grain aspect ratio in the ELSC model, which is often not considered in the literature, is found to be an important parameter in affecting the identified SEC. The Bayesian inference suggests a high probability for non-spherical grains (aspect ratio of ∼3.8±0.8) : C11β=92.6±19.1GPa,C12β=82.5±16.3GPa,C44β=43.5±7.1GPa. The uncertainty obtained by Bayesian approach lies in the range of ~1-3 GPa for the shear modulus μ′=C11β−C12β2, and ~7 GPa for the shear modulus μ″=C44β, while it is significantly larger in the case of the bulk modulus C11β+2C12β3 (~17-24 GPa).

Biological Safety Evaluation and Surface Modification of Biocompatible Ti-15Zr-4Nb Alloy.

We performed biological safety evaluation tests of three Ti–Zr alloys under accelerated extraction condition. We also conducted histopathological analysis of long-term implantation of pure V, Al, Ni, Zr, Nb, and Ta metals as well as Ni–Ti and high-V-containing Ti–15V–3Al–3Sn alloys in rats. The effect of the dental implant (screw) shape on morphometrical parameters was investigated using rabbits. Moreover, we examined the maximum pullout properties of grit-blasted Ti–Zr alloys after their implantation in rabbits. The biological safety evaluation tests of three Ti–Zr alloys (Ti–15Zr–4Nb, Ti–15Zr–4Nb–1Ta, and Ti–15Zr–4Nb–4Ta) showed no adverse (negative) effects of either normal or accelerated extraction. No bone was formed around the pure V and Ni implants. The Al, Zr, Nb, and Ni–Ti implants were surrounded by new bone. The new bone formed around Ti–Ni and high-V-containing Ti alloys tended to be thinner than that formed around Ti–Zr and Ti–6Al–4V alloys. The rate of bone formation on the threaded portion in the Ti–15Zr–4Nb–4Ta dental implant was the same as that on a smooth surface. The maximum pullout loads of the grit- and shot-blasted Ti–Zr alloys increased linearly with implantation period in rabbits. The pullout load of grit-blasted Ti–Zr alloy rods was higher than that of shot-blasted ones. The surface roughness (Ra) and area ratio of residual Al2O3 particles of the Ti–15Zr–4Nb alloy surface grit-blasted with Al2O3 particles were the same as those of the grit-blasted Alloclassic stem surface. It was clarified that the grit-blasted Ti–15Zr–4Nb alloy could be used for artificial hip joint stems.

Study of the Effect of Carbon on the Deformation Behavior and Microstructure of a Ti–10V–2Fe–3Al Alloy

Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis are used to study the structure, phase composition, and deformation behavior of a titanium Ti–10V–2Fe–3Al alloy with different carbon contents. It is shown that as the carbon content in the alloy increases to the maximum carbon solubility, the dispersity of the secondary α-phase increases and, therefore, the strength of the alloy increases. After reaching the carbon solubility limit, titanium carbide particles are observed in the alloy structure; the morphology of the particles and their sizes are similar to those of the primary α-phase. The titanium carbide particles do not affect the strength and plasticity characteristics of the alloy during tensile tests and retain their initial shape after deformation. At the stage of strain localization, titanium carbide particles are sites of micropore nucleation.