High-strength Titanium Alloy Research Articles

The effect of surface roughness and microstructure on fretting fatigue properties of TC21 based on hierarchical multiscale modeling

In the aviation industry, structures made from high-strength titanium alloy TC21 frequently suffer from fretting fatigue (FF), resulting in shortened service life. FF is significantly influenced by the surface integrity (SI) parameters. This study aims to investigate the effect of SI parameters, including microstructure and surface roughness, on the FF properties of TC21. It is implemented by introducing the crystal plasticity finite element method (CPFEM). The CPFEM parameters of single grain of α-Ti in TC21 were obtained by fitting the experimental and simulation data of nanoindentation test. On this basis, the FF of TC21 is studied by means of a hierarchical multiscale modeling method, which couples a global model with a CPFEM sub-model. In the global model, surface roughness was considered. While in the CPFEM sub-model, microstructure was incorporated as well. The FF sub-model shows that the stress was unevenly distributed due to the inconsistency in mechanical behavior of TC21. both the maximum von Mises stress and the maximum Fatemi-Socie (FS) parameter occurred at the grain boundaries in the subsurface layer. The prismatic slip system is highly sensitive to FF. For the orientation of <100>∥X-axis, the lowest FS value of 1.137×e-2 was obtained at the surface roughness of 0.8μm, meaning the smallest damage. While the orientation of <110>∥X-axis and random orientation are most sensitive to FF, their FS values reaching 2.019×e-2 and 2.090×e-2, respectively.

Microstructural evolution and mechanical property of high-strength metastable β titanium alloy joint via electron beam welding

Obtaining a fundamental understand of the relationship between weld microstructure and mechanical properties is critical for ensuring a high weld quality. This work explored the micro-mechanism responsible for the mechanical properties of a 10-mm-thickness metastable β titanium alloy (Ti–3Al–5Mo–4Cr–2Zr–1Fe, wt.%) joint welded by electron beam welding (EBW). Weld microstructure and its evolution behavior were revealed by means of multi-scale microstructure characterization. Obtained results indicate that the absence of α phase and formation of nano-scale ω particles occurred in the coarse columnar β grains of the fusion zone (FZ). Intense dissolution and significant coarsening of secondary α phase occurred in the heat affected zone. Between the FZ and HAZ, a partially melted zone was observed and contains few equiaxed β grains. Compared to the base material, the as-welded EBW joint shows significant softening in weld seam and a slight decrease of 17% in ultimate tensile strength, while a severe reduction of 73% in elongation. It was observed that majority of plastic deformation is confined to the narrow FZ, indicating a significant localization of tensile strain. This leads to premature fracture of the joint within the FZ and consequently to significant deterioration of the overall ductility. This work contributes to advancing the understanding of the role of microstructural evolution on the mechanical properties of high-strength titanium alloy joints via EBW.

Effect of deformation temperature on the microstructure and texture evolution of Ti-6Al-4Zr-2Mo-6V alloy

In this work, the effect of deformation temperature on the microstructure, texture, and tensile properties of a Ti-6Al-4Zr-2Mo-6V (wt. %) alloy was systematically investigated. The whole samples were composed of an equiaxed α phase, a strip α phase, and a β transformed microstructure. The recrystallization area fraction increased with the increase of deformation temperature. The orientation distribution of a retained β phase was {001}β⟨110⟩β texture regardless of deformation temperature. The textured microstructure of an α phase was {12¯10}α⟨101¯0⟩α under the 810 and 840 °C condition. Additional {112¯0}α⟨0001⟩α texture was observed as the rolling temperature increased to 870 °C. The yield strength and the tensile strength of a rolling direction were lower than that of a transverse direction. The yield strength of a rolling direction and a transverse direction were both above 990 MPa when the deformation temperature was 840 °C. In summary, the present study provided theoretical guidance for the high strength titanium alloy applied for the marine engineering field.

Effect of laser shock peening on the surface integrity and fretting fatigue properties of high-strength titanium alloy TC21

High-strength titanium alloy TC21 is often used to make aircraft load-bearing components in the aviation field. However, due to vibration, load-bearing components often suffer from fretting fatigue (FF), which greatly reduces their actual service life. Nowadays, laser shock peening (LSP) is being recognized as an effective strengthening process for many materials. Therefore, in this study, the effectiveness of LSP on the strengthening of high-strength titanium alloy TC21 is studied, in terms of surface integrity and FF properties. TC21 fretting specimens and tests are designed. Before fretting tests, the specimens are processed by LSP with varying laser pulse energies, number of shocks and overlap rate, and their surface integrity and FF properties are analyzed. It is found that the greater the laser pulse energy and number of shocks, the higher the surface hardness and compressive residual stress, the more the grain refinement, the greater the improvement in FF life. Under 32J-50%-T1, the FF life is improved by 191.3% compared with BM. But the overlap rate has little effect on surface integrity and FF life. Meanwhile, there forms amorphous structures, which tended to be transformed into nanograins during fretting process. This transformation is helpful for prolonging FF life due to its action of energy absorption. This study reveals the strengthening mechanism of LSP on TC21 and its effect on the FF properties of TC21 specimens.

Effect of laser remelting on microstructure evolution and high-temperature fretting wear resistance in a laser-cladding self-lubricating composite coating on titanium alloy substrate

TC21 titanium alloy possesses the advantage including high strength, low density, and great resistance to damage. Combining it with surface modification technology, it is expected to improve the performance of aviation structural components. This work applied laser remelting technology to realize surface modification, and the hardness and fretting wear properties of the coating were investigated. This research has found that laser remelting technology can effectively refine grain size and improve the performance of coatings. By exploring different laser remelting powers (600 W, 900 W, 1200 W) and the different diameters of laser beam (3 mm, 6 mm), the optimal laser process was obtained with laser power and spot diameter of 600 W and 6 mm, respectively. The average grain size is 2.1 μm. The laser remelting coating has an average microhardness about 980 HV0.2, and it is 2.5 times and 1.3 times higher than the substrate and laser cladding hardness, respectively. A minimum coefficient of friction (COF) about 0.5 was obtained by the laser remelting coating, and the wear rate reaches the lowest of 1.87 × 10−6 mm3/(N·m) at fretting temperature with 500 °C. The abrasive wear and adhesive wear were the main wear mechanisms, and accompanied by oxidative wear. This study provides important reference for improving the performance of high-strength titanium alloy to obtain low defect, high-performance coatings with stable quality.

Effect of Ta/Ni dual-interlayer on the microstructure and properties of high strength titanium alloy and steel composite plate

The combination of ultra-high-strength Ti-6Al-4V (TC4) titanium alloy and 30CrNiMoNb (6211) steel was achieved by adding Ta/Ni dual-interlayer and rolling at 950 °C through welding a symmetrical blank sleeve with a vacuum electron beam. In order to unveil the metallurgical bonding mechanism and the interfacial structure, SEM, XRD, and compression-shear performance tests were used. The results revealed the presence of thin-film brittle TiC, TiFe, and TiFe2 compounds at the TC4/6211 interface, resulting in an increased risk of interface mismatch and brittle fracture along the matrix phase interface, and the average interfacial bonding strength was tested at 323 MPa.In contrast, the TC4-Ta interface and the 6211-Ni interface in the TC4/Ta/Ni/6211 composite plate displayed good solid solution formation. The strengthening mechanism of the Ta/Ni dual-interlayer interfacial bonding was analyzed using selected area electron diffraction (SAED), revealing that the Ta-Ni diffusion region consisted of Ni3Ta and Ni2Ta. The addition of the Ta/Ni dual-interlayer prevented the aggregation of Ti and Fe atoms to form Ti-Fe compounds. The malleable intermetallic compounds of Ni3Ta and Ni2Ta effectively coordinated deformation, leading to an average interfacial bonding strength of 469 MPa, which was 45.2 % higher than the composite plate without Ta/Ni dual-interlayer.

High-throughput determination of interdiffusivity and atomic mobilities in bcc Ti–Cr–Mo alloys

A comprehensive understanding of the diffusion coefficients and atomic mobilities in the Ti–Cr–Mo system is crucial for establishing an atomic mobility database for titanium-based high-strength titanium alloys. In the present work, nine sets of solid/solid diffusion couples were prepared and measured in bcc Ti–Cr–Mo alloys, with the temperatures ranging from 1373 to 1473 K. Scanning electron microscopy (SEM), and Electro Probe Micro-Analysis (EPMA) techniques were used to respectively test its microstructure and composition distance. The diffusion coefficients in bcc Ti–Cr–Mo alloys were determined using the Matano-Kirkaldy method and numerical inverse method respectively. The diffusion coefficients obtained from the above two methods exhibit good consistency. The atomic mobility parameters for the Ti–Cr–Mo systems were provided with the assistance of HitDIC software. A three-dimensional plot of interdiffusivities was generated for chromium and molybdenum contents ranging from 0 to 20 mol % and 0–14 mol %. Moreover, the application of the Arrhenius equation enabled the determination of changes in frequency factors and activation energies concerning temperature and composition.

Enhancing strength-ductility synergy in metastable β-Ti alloys through β-subgrains-mediated hierarchical α-precipitation

Titanium alloys can achieve ultrahigh strength through precipitation hardening of secondary α-phase (αs) from β-matrix but often compromise ductility due to the conventional strength-ductility trade-off. In this study, a new strategy based on β-subgrains-mediated hierarchical α-precipitation is devised to balance the conflict in Ti-6Al-2Mo-4Cr-2Fe (wt.%) alloy through a unique combination of hot rolling, short-term solid solution, and aging treatment, i.e., RSST+A. Tensile testing reveals that the RSST+A samples exhibit ultrahigh strength of ∼1581 MPa and decent ductility of ∼8.4 %, surpassing ∼1060 MPa and ∼2.7 % of the corresponding RSST counterparts without final aging treatment. This remarkable strengthening and counterintuitive ductilizing is attributed to the architecting of β-subgrains-mediated hierarchical α-precipitates as a result of our specific processing approach. The designed short-term solution introduces abundant β subgrains that are transformed from the retained intensive dislocations during hot rolling. The β subgrain boundaries subsequently promote a dramatic precipitation of α allotriomorphs (αGB) and Widmanstätten side-plates (αWGB), which effectively subdivides β grains into numerous tiny independent deformation units. Consequently, plastic strain is uniformly partitioned into a large number of small aged β subgrains during tension, which strongly impedes strain localization that would typically occur across multiple β subgrains in the fashion of long straight slip bands in the case of the RSST samples. Furthermore, the hierarchical α structure also postpones uncontrollable cracking even when structural damage occurs at the last stage of straining. These findings demonstrate that appropriately manipulating microstructure through elaborately designing processing routes enables unexpectedly ductilizing high-strength titanium alloys in the precipitation-hardening state.

Enhanced comprehensive mechanical properties of laser additive manufactured TC17 by design of new heat treatment based on continuous cooling transition

Heat treatment is critical for enhancing the mechanical properties of high strength titanium alloys, especially for exploiting the potential of laser additive manufactured titanium alloys. In this work, the influence of the cooling rate of continuous cooling transition on microstructure evolution and mechanical behavior was investigated in TC17 titanium alloy fabricated by laser directed energy deposition (LDED) technology. It was found that the number density and orientation characteristics of grain boundary α phases (αGB) are jointly influenced by the cooling rate and the structure of β/β grain boundaries (GBs). The average number density (λavg) of αGB has a consistent trend with the degree of variant selection (DVS) for precipitated α clusters subsequently, which is attributed to the autocatalytic effect of the pre-existing α on the post-precipitated α phases. The largest λavg of αGB and the highest DVS of α clusters could be simultaneously obtained at a suitable cooling rate (4 °C/min). In that case, plenty of α/β phase interfaces and dominant variant type ensure high strength, meanwhile, the combinations of activated multi-slip systems and varied crack propagation paths extend work-hardening to maintain greater plastic deformation. This paper provides a novel thought for designing customized heat treatments of LDEDed high strength titanium alloys, and more importantly, promotes the engineering applications of large and complex components prepared by additive manufacturing technology.

Abnormal aging behaviors induced by high-density dislocations for an ultra-high-strength titanium alloy prepared by laser-directed energy deposition

Additively manufactured high-strength titanium alloys generally possess equal strength and lower plasticity compared to wrought alloys owing to the different microstructures formed in the aging treatment. To examine the formation mechanism of these microstructures, an ultra-high-strength titanium alloy TB18(Ti-4.2Al-5V-5Cr-5Mo-1Nb) was prepared by laser direct energy deposition (LDED) and forging respectively, and the aging behaviors and microstructures were characterized and compared in depth. It is found that during aging, the precipitation of the LDEDed alloy is 1–2 h earlier than that of the wrought alloy, and precipitates primarily form at the reticular sub-grain boundaries. Fine short-rod α laths then form inside the sub-grains due to the inhibition of the reticulations. The sub-grain boundaries in LDEDed alloy are generated due to the local deformation and recovery of the inter-dendritic zone rich of Cr and O atoms and show high thermal stability in the solution treatment, which differs from that of the wrought alloys. These boundaries possess a dislocation density several times higher than that of the inner-grain zones and promote the prior precipitation of α laths with Type 2 orientations at the early stage of aging. In the tensile test of the aged alloys, the dislocations in the LDEDed alloy pile up at the α/β interface, which can cause stress concentration and damage the plasticity.

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

Optimization of machining parameters for turning operation of heat-treated Ti-6Al-3Mo-2Nb-2Sn-2Zr-1.5Cr alloy by Taguchi method

TC21 alloy is a high-strength titanium alloy that has been gaining attention in various industries for its excellent combination of strength, toughness, and corrosion resistance. Given that this alloy is hard to cut material, therefore this study aims to optimize the process parameters of Turing this alloy under different conditions (i.e. as-received alloy, and heat-treated alloy). The L9 Taguchi approach-base orthogonal array is used to determine the optimum cutting parameters and the least number of experimental trials required. The achievement of this target, three different cutting parameters are used in the experimental work; each cutting parameter has three levels. The cutting speeds are chosen as 120, 100, and 80 m/min. The feed rates’ values are 0.15, 0.1, and 0.05, mm/rev, and the depth of cut values are 0.6, 0.4, and 0.2 mm. After applying three steps of heat treatment (First step: is heating the sample to 920 °C for 1 h then decreasing to 820 °C also for 1 h, second step: cooling the sample to room temperature by water quenching (WQ), the third step: holding the sample at 600 °C for 4 h (Aging process)). The results revealed that the triple heat treatment led to the change in the microstructure from (α + β) to (α + β) with secondary α platelets (αs) formed in residual β matrix leading to a decreased surface roughness by 56.25% and tool wear by 24.18%. The two most critical factors that affect the tool insert wear and surface roughness are the death of cut and cutting speed, which contribute 46.6% and 46.7% of the total, respectively. Feed rate, on the other hand, has the least importance, contributing 20.2% and 31.9% respectively.

Effect of peak stress and dwell time on the fatigue damage behavior of Ti-22Al-23Nb-2(Mo, Zr) alloy with lamellar microstructure

Ti2AlNb alloy is one of the candidate high strength titanium alloy materials under consideration for compressor disc, which will endure dwell loading at high peak stress level during service. In this work, low cycle fatigue (LCF) and low cycle dwell fatigue (LCDF) deformation behaviors and damage mechanism of Ti2AlNb alloy with lamellar microstructure under high loading level were investigated. The results show that fatigue life is highly dependent on the peak stress (σpeak) and dwell time (tdwell). With increasing the σpeak, the LCF life decreases gradually since higher loading stress can accelerate plastic strain accumulation and lead to faster crack propagation. When at the same σpeak, the LCDF life is lower than the LCF life due to greater plastic strain accumulation caused by dwell effect, indicating a dwell life debit of the Ti2AlNb alloy. Moreover, dwell fatigue sensitivity exhibits an increasing trend as the tdwell increases. Under different loading waveforms, the fractography shows remarkably different features. Crack source of LCF appears on sample surface, while crack source of LCDF appears on surface and sub-surface of sample. The research of LCDF behavior is relevant to aviation industry to prevent premature failure of rotating components made of Ti2AlNb alloys.

Determining technological parameters for obtaining ta15 titanium alloy blanks with improved mechanical characteristics using the electron-beam 3D printing method

The object of this study is the process of electron beam 3D printing of articles made of TA15 titanium alloy powder. Peculiarities of the structure and properties formation of alloy blanks, obtained by this method have been described. Influence of process parameters (electron beam power and geometric scanning parameters) on the characteristics of the material were considered. Step of displacement of the beam trajectory changed from 0.1 to 0.25 mm with an interval of 0.05 mm. Specific energy of the electron beam varied from 20 to 70 J/mm3 for every trajectory displacement step. The macrostructure was examined visually while the microstructure was studied by optical microscopy. Mechanical properties were determined by uniaxial tension and impact bending tests. It was established that depending on the 3D printing parameters the macrostructure of most samples is dense but with unfavorable parameters non-fusions or shrinkage porosity defects may form. The microstructure of the dendritic type has an α´+β lamellar-acicular morphology, its dispersity and shape of α´–phase areas vary depending on the process parameters. A scanning step of 0.2 mm and a beam energy of 40 J/mm3 allows obtaining a dispersed microstructure in which there are no non-fusions and shrinkage micropores. The value of the Rm is 27 %, and the R0.2 is 24 % higher than that of the alloy obtained by the conventional technology of electron beam melting. The A5 is 3.2 times higher. However, impact toughness of the sample with dendrite unfavorable orientation to the direction of load applying may be lower compared to conventional technology. The results could be used for devising commercial technology of high strength titanium alloys parts produced by 3D printing

Subsurface deformation mechanism and the interplay relationship between strength-ductility and fretting wear resistance during fretting of a high-strength titanium alloy

Fretting wear damage of high-strength titanium fasteners has caused a large number of disastrous accidents. Traditionally, it is believed that both high strength and excellent ductility can reduce fretting wear damage. However, whether strength and ductility are contradictory or not and their appropriate matching strategy under the external applied normal stress (Fw) are still confusing problems. Here, by analyzing the subsurface-microstructure deformation mechanism of several samples containing various α precipitate features, for the first time, we design strategies to improve fretting damage resistance under different matching relation between Fw and the tensile strength of materials (Rm). It is found that when Fw is greater than Rm or Fw is nearly equivalent to Rm, the deformation mechanism mainly manifests as serious grain fragmentation of β and αGB constituents. Homogeneous deformation in large areas only reduces damage to a limited extent. It is crucial to improve the strength to resist cracking and wear, but it is of little significance to improve the ductility. However, when Fw is far less than Rm, coordinated deformation ability reflected by ductility plays a more important role. The deformation mechanism mainly manifests as localized deformation of β and αGB constituents (kinking induced by twinning and spheroidizing). A unique composite structure of nano-grained/lamellar layer and localized deformation transition layer reduces fretting damage by five times compared with a single nano-grained layer. Only when the strength is great enough, improving the plasticity can reduce wear. This study can provide a principle for designing fretting damage resistant alloys.

A study on the collaborative deformation mechanisms of continuous and discontinuous dynamic recrystallization under low strain rates for the Ti6455x alloy with a low activation energy

To reveal the collaborative dynamic recrystallization mechanisms occurring only at low strain rates, the Ti6455x titanium alloy was designed and prepared by hot deformation. The microstructure, activation energy, and the dynamic recrystallization (DRX) process under different strain rates and temperatures were investigated, with a corresponding mechanism revealed for the first time. Results show that at low strain rates of 0.01 and 0.001 s-1, as temperature from 1173 to 1223 K, the grain size decreases, jagged bumps appear at the grain boundaries and new small grains are produced. The activation energy of Ti6455x titanium alloy is 128.63 kJ/mol. Quantitative calculations revealed that the thermal deformation mechanisms depend on the dissipation efficiency factor, η. With an increasing value of η, the dynamic softening mechanism changes from dynamic reversion (DRV) to DRV and continuous dynamic recrystallization (CDRX). While with a high η value, CDRX and discontinuous dynamic recrystallization (DDRX) occur at a temperature of 1223 K, and a strain rate of 0.001 s-1. The collaborative deformation process proceeds because: low activation energy titanium alloys facilitate the rotation of sub-grain boundaries, while dislocations can easily migrate. This condition enables CDRX to occur, leading to the refinement of grains and producing jagged grain boundaries. Then, CDRX provides nucleation sites for DDRX, promoting grain boundary migration and breaking down grains. This mechanism can significantly refine the grain size and improve mechanical properties. It is shown that both the design of low activation energy alloys and controlling hot processing conditions are effective in the development of high-strength titanium alloys.

An insight into texture evolution and tailoring during multi-pass cold pilgering of high-strength titanium alloy tubular materials

The high-strength titanium alloy tubular materials are extensively applied in aviation and aerospace industries, wherein the mechanical properties, subsequent formability and in-service performance of the tube are strongly dependent on the texture variation. Cold pilgering has been a favorable fabrication technology for hard-to-deform tubes, however, the coupling effects of inherently low symmetric and complex multi-pass thermal-mechanical histories led to the significant diversity of the texture evolution of high-strength titanium alloy tubular materials. The traditional methods which mainly dependent on the Q value and deformation degree adjusting are difficult to achieve the precise tailoring of texture in multi-pass cold pilgering process. In this work, to break the limitation of the traditional method, by taking into account the mechanical properties iterating in each pass and the texture inheritance in recrystallization annealing process, a numerical computation platform for texture evolution prediction during multi-pass cold pilgering of titanium alloy tube was firstly established. The accuracy and reliability of the platform was verified by the 3-pass cold pilgering experiment and texture characterization. Secondly, the crucially effect of the initial texture was deeply explored in this work, the results indicated that the desired radial texture would be enhanced only when the Q value and area reduction ratio (AR) exceed the corresponding threshold under the specific initial texture, in which the tensile twinning was the vital deformation mode for the grain rotation and texture evolution. Thirdly, the quantitative correlation between processing conditions and finished radial texture intensity fRD was established which comprehensively introduced the Q value, AR and initial texture intensity. In contrast to the accuracy of 59.4% based on the single factor Q value and 75.1% based on double factor of Q value and AR, the prediction accuracy of the quantitative correlation established in this work upgraded to approximate to 95%. Finally, taking the contractile strain ratio (CSR) as the index to reflect the macro anisotropy mechanical properties, the bonds that unite the processing conditions, fRD and CSR were also built.

Evolution of the Microstructure and Mechanical Properties of a Biomedical Ti-20Zr-40Ta Alloy during Aging Treatment

The research focus in the field of medical titanium alloys has recently shifted towards the development of low-modulus and high-strength titanium alloys. In this study, the influence of aging temperature on the microstructure and mechanical properties of a β-type Ti-20Zr-40Ta alloy (TZT) was investigated. It was found that the recovery and the recrystallization occurred in the as-rolled alloy depended on the aging temperature. The periodically distributed Ta-lean phase (β1) and Ta-rich phase (β2) were produced by the spinodal decomposition in all the samples aged at different temperatures. The spinodal decomposition significantly influenced the mechanical properties and deformation mechanisms of the TZT alloy. Upon aging at 650 °C and 750 °C, the as-rolled alloy exhibited a double-yield phenomenon during tensile testing, indicating a stress-induced martensitic transformation; however, its ductility was limited due to the presence of ω phases. Conversely, aging at 850 °C resulted in an alloy with high strength and good ductility, which was potentially attributed to the enhanced strength resulting from modulated structures introduced with spinodal decomposition.

A framework for computer-aided high performance titanium alloy design based on machine learning

Titanium alloy exhibits exceptional performance and a wide range of applications, with the high performance serving as the foundation for the development. However, traditional material design methods encounter numerous calculations and experimental trial-and-error processes, leading to increased costs and decreased efficiency in material design. The data-driven model presents an intriguing alternative to traditional material design methods by offering a novel approach to expedite the materials design process. In this study, a framework for computer-aided design high performance titanium alloys based on machine learning is proposed, which constructs an intelligent search space encompassing various combinations of 18 elements to facilitate alloy design. Firstly, a proprietary dataset was constructed for titanium alloy materials using feature design and a combination of unsupervised and supervised feature engineering methods. Secondly, six machine learning algorithms were employed to establish regression models, and the hyperparameters of each algorithm were optimized to improve model performance. Thirdly, the model was screened using five regression algorithm evaluation methods. The results demonstrated that the selected optimized model achieved an R2 value of 0.95 on the verification set and 0.93 on the test set, yielding satisfactory outcomes. Finally, a comprehensive model framework along with an intelligent search methodology for designing high-strength titanium alloys has been established. It is believed that this method is also applicable to other properties of titanium alloys and the optimization of other materials.

High-throughput determination of the interdiffusion coefficients and atomic mobilities in bcc Ti–Fe–V alloys

A comprehensive understanding of diffusion kinetics of the Ti–Fe–V system is crucial for elucidating the solidification process in high-strength titanium alloys. In this paper, ten sets of diffusion couples within bcc Ti–Fe–V alloys that underwent annealing at temperatures of 1273K, 1323K, and 1373K were prepared. Composition-distance curves were determined using the electron probe microstructure analysis technique. Atomic mobility parameters and interdiffusion coefficients were obtained using the numerical inverse method with the assistance of HitDIC software. It should be noted that the atomic mobility parameters for Ti–Fe and Ti–V were reoptimized using the most up-to-date thermodynamic descriptions. This approach enables the acquisition of comprehensive data regarding the temperature-composition relationship in diffusion. D˜FeFeTi exhibits a markedly greater value compared to D˜VVTi. Both D˜FeFeTi and D˜VVTi demonstrate an increase with the increase of temperature. Furthermore, the Arrhenius equation can be applied to solve for the variation in frequency factors and activation energies concerning temperature and composition.