Vanadium Alloys Research Articles

Antimicrobial Effect of Zinc Oxide Nanoparticle Coating on Titanium 6 Aluminum 4 Vanadium (Ti-6Al-4V)-Fixed Orthodontic Retainer Substrate

Abstract Objectives Due to its excellent biocompatibility, superior mechanical qualities, and exceptional corrosion resistance, titanium 6 aluminum 4 vanadium (Ti-6Al-4V) alloy is frequently used for medical and orthodontic purposes as a fixed retainer after active orthodontic treatment. Titanium lacks the antibacterial characteristics and is bioinert, this may influence the usage of such materials in the field of biomedical applications. Bacterial adhesion to the orthodontic retainer surface is a common first step in infection; this is followed by bacterial colonization ending with the formation of a biofilm. Once biofilm forms, it is highly resistant to medicines and the host immune system's defense mechanism, making it difficult to remove the biofilm from orthodontic retainer. This study aimed to test the antimicrobial effect of a zinc oxide (ZnO) nanoparticle coating on Ti-6Al-4V orthodontic retainers. Materials and Methods ZnO nanoparticles, with a particle size of 10 to 30 nm, were used to coat the alloy using the electrophoretic deposition method. Various parameters and surface characterization tests were employed to obtain an optimized sample. This sample was subjected to the microbial adherence optical density test to examine the adherence of Streptococcus mutans, Lactobacillus acidophilus bacteria, and Candida albicans. Results The optimized sample had a 5-mg/L ZnO concentration, applied voltage of 50 V, and a 1-cm distance between electrodes. The ZnO coating significantly reduced microbial adherence compared to uncoated samples, effectively inhibiting bacterial development. Conclusion Electrophoretic deposition is an efficient and cost-effective technique for coating orthodontic titanium retainer substrates. Coating Ti-6Al-4V with ZnO nanoparticles increased the antimicrobial effectiveness of the material and as the concentration of the nanoparticles rises, the antimicrobial effect increases too.

Severe plastic cold rolling effects in nickel–vanadium alloy: Microstructure, texture evolution and mechanical properties

The microstructural characteristics and morphological attributes of the target material, along with its intrinsic properties, can significantly influence the performance of the resultant film. Currently, commercially available nickel-vanadium targets employed in the industry have not been subjected to investigations aimed at controlling grain size and grain orientation. This study examines the effects of unidirectional rolling at room temperature, combined with substantial deformation, on the alterations in microstructure, texture evolution, and mechanical properties of the NiV7 alloy. The process of severe plastic cold rolling leads to a continuous elongation and refinement of the grains. The changes in microstructure and texture of the cold-rolled sheets were analyzed using electron backscatter diffraction (EBSD) technology. At an 80% reduction, a significant number of sub-grains are observed, which transform into deformed grains as the reduction reaches 95%. With a thickness reduction of 96.6%, the average grain size is approximately 1.10 μm. Further increases in reduction do not lead to significant alterations in the grain structure; instead, the grain orientation progressively becomes more uniform with higher levels of deformation. The combination of substantial deformation and lower rolling rates results in an increased number of high-angle grain boundaries. The alloy displays various textures throughout the rolling process, including S-type, copper-type, brass-type, fiber, and cubic textures. Notably, the prevalence of S-type and fiber textures diminishes as the degree of deformation increases, while the cubic texture becomes increasingly prominent. Upon achieving a reduction of 95%, the cubic texture emerges as the dominant texture. A transmission electron microscope (TEM) was utilized to examine the extensive array of dislocations, dislocation cells, dislocation walls, and shear bands generated during the cold rolling process. At a deformation level of 96.6%, the ultimate tensile strength of the alloy demonstrates a significant enhancement, attributed to mechanisms of dislocation strengthening and grain strengthening, reaching a value of 1231 ± 20 MPa, accompanied by a post-fracture elongation of approximately 2%. The ultimate tensile strength exhibited an increase of 781 ± 20 MPa compared to the sample prior to the rolling process; however, there was a notable reduction in plasticity.

Dissimilar joining of Ti–6Al–4V to 316L stainless steel by a novel joining process based on arc additive manufacturing and combined twin-wire arc welding

The joining structure of Ti–6Al–4V to 316L stainless steel has potential demands in many fields. However, it is very difficult to avoid the formaiton of intermetallic compounds (IMCs) of the weld between Ti–6Al–4V to 316L stainless steel, which will severely decrease joint properties. In this paper, a novel joining technology that combines the single wire backing arc welding and the spatially arranged combined twin-wire arc welding was utilized to join Ti–6Al–4V and 316L stainless steel. Copper alloy wire (S214) and vanadium alloy wire (V01) were used as filler metals to produce two isolation layers, which prevented the formation of IMCs. The phase compositions at the Fe/Cu, Cu/V and V/Ti interfaces were Fe(S,S) + Cu(S,S), Cu(S,S) + V(S,S) and V(S,S)+(β-Ti, V)SS respectively. The distribution of the spherical and clustered V(S,S) particles in the matrix at the Cu/V interface contributes to dispersion strengthening and solid solution strengthening of the interface. Tensile strength of 394 MPa with an elongation of 2.53% was achieved. The joint fractured at the Cu/V interface of the single wire backing arc weld and the Cu zone of the spatially arranged combined twin-wire arc weld respectively. Dimple plastic fracture modes were detected in the joints. This technology is not only applicable to Ti–6Al–4V titanium alloy/316L stainless steel dissimilar metal joining, but also provides a new research strategy for the joining between other dissimilar metals.

Migration mechanisms of mono-/di-interstitials in vanadium with alloying Ti/Cr

Self-interstitial atoms (SIAs) are the dominant self-defects at equilibrium in metals, but many questions such as their diffusion characteristics are still open, and studies of the Ti/Cr effect on the kinetics of SIAs are very scarce in vanadium alloy. In this work, we systemically investigated the migration mechanisms of mono/di-interstitials as well as the effect of alloying elements Ti/Cr on the kinetics of SIAs using first-principles calculations. The findings reveal that 〈111〉SIA exhibits three migration mechanisms, including one dimensional (1D) migration, translation-rotation and translation, corresponding energy barriers of 0.008, 0.19 and 0.44 eV. Different migration pathways are activated at high temperatures, which supports the experimental observation of 3D migration of SIAs under high temperatures. We determined the di-SIA (two parallel 〈111〉SIA) migration by both successive and simultaneous jumping paths, the lowest migration barrier is 0.009 eV via successive jumping path passing a translation state. Moreover, based on three migration mechanisms of SIA, SIA migrating to Ti region possesses the lower barrier than pure vanadium, in verse the barrier is relative high and then hinders the SIA diffusion. The alloying Ti has a pinning effect on SIAs. And we explored how SIA to form mixed V-Cr interstitial and its migration of 〈111〉V-Cr. Finally, we estimated the effect of Ti on SIA diffusivity by empirical formulas.

Neural network interatomic potential-driven analysis of phase stability in Ti–V alloys at the atomistic scale

The evolution of the ω phase in titanium–vanadium (Ti–V) alloys is critical for their mechanical properties, particularly in aerospace and biomedical applications. This study employs a Rapid Artificial Neural Network (RANN) potential to model the ω phase evolution at the atomistic level, demonstrating a high degree of consistency with experimental observations, unlike the Modified Embedded Atom Method (MEAM), which fails to capture this phase transformation accurately. RANN simulations replicate key phenomena such as the nucleation of α precipitates at ω/β interfaces and accurate lattice orientations, enhancing our understanding of phase stability and transformation kinetics. The findings affirm that RANN potentials can significantly improve the prediction accuracy of complex material behaviors, offering a powerful tool for designing advanced materials with tailored properties such as solute effect in various stacking fault energies. This approach not only bridges the gap between theoretical predictions and empirical data but also sets a new direction for future research in materials science, emphasizing the integration of machine learning techniques in the development and optimization of new alloys.

Remarkable mechanical properties at room and cryogenic temperatures in a metastable high-entropy system through BCC and HCP martensitic transformations

Metastable high-entropy alloys (HEAs) with strong transformation-induced plasticity (TRIP) effects are quite desirable from the standpoint of mechanical performance. This can be achieved through ε (HCP) and α΄ (BCC) martensitic transformations during deformation, for which their importance and effectiveness should be systematically evaluated. Accordingly, in the present work, by adjusting the chemical composition of the FeCoCrNiMnV system, the formation of ε and α′-martensite was tailored. Vanadium alloying resulted in a single FCC phase, and increasing Fe at the expense of Co promoted the formation of α′-martensite over ε-martensite. The V-free Fe45Co30Cr15Ni5Mn5 HEA exhibited high strength but low ductility. However, the V-containing Fe40Co30Cr15Ni5Mn5V5, Fe45Co25Cr15Ni5Mn5V5, and Fe50Co20Cr15Ni5Mn5V5 HEAs showed much better tensile properties at room and cryogenic temperatures. The last HEA with the highest Fe content showed a remarkable room-temperature strength-ductility synergy with an ultimate tensile strength (UTS) of 826 MPa, a total elongation of 88 %, and tensile toughness of 604 MJ m−3, ascribed to the remarkable TRIP effect by the α′-martensite formation. At cryogenic temperatures, this effect resulted in a superior strength-ductility balance with a UTS of 1511 MPa, a total elongation of 68.9 %, and a tensile toughness of 814 MJ m−3. The results showed that α′-martensite formation is more important for overcoming the strength-ductility trade-off compared to ε-martensite formation in HEAs.

First principles study of the behavior of H atoms at TiO/V interface

TiO-precipitate and H atom are crucial factors for degradation of mechanical properties in vanadium alloys under irradiation environment. Herein, the behaviors of H atom at TiO/V interface are systemically studied by first principles calculations to elucidate the influence of TiO-precipitate on the H bubble formation. H atom prefers to dissolve in octahedral interstitial site (OIS2) with smaller lattice distortion and stronger bonds. The electronic interaction between H atom near monovacancy at the interface and surrounding atoms is enhanced with the existence of the TiO-precipitate. The capture of four H atoms in monovacancy is thermodynamically optimal, and the electronic action mainly contributes to the total trapping energy by monovacancy. The total trapping energy by multi-vacancy clusters is independent of the number of vacancies. H atoms trapped by vacancies cannot form H2 molecule at TiO/V interface. Our work can provide theoretical guidance for further understanding the H bubbles formation in vanadium alloys.

Effect of Graded Microstructure on Magnetic Properties of Rotary Friction Welded Cobalt–Iron–Vanadium Alloy with SS 321 Alloy

Effect of Graded Microstructure on Magnetic Properties of Rotary Friction Welded Cobalt–Iron–Vanadium Alloy with SS 321 Alloy

Deuterium permeation performance of V4Cr4Ti/RAFM steel joint with in-situ formed carbide interlayer during diffusion bonding

Vanadium alloy (V4Cr4Ti) is a structural material used in future fusion reactors owing to its inherent advantages of high-temperature strength and neutron irradiation resistance. Oxygen pickup and high hydrogen isotope permeability are the two major concerns for their application in various types of blankets. To solve these issues, a bimetallic joint was designed with a CLF-1 layer of reduced-activation ferritic/martensitic (RAFM) steel to resist corrosion and a CLF-1/V4Cr4Ti bonding interface to suppress hydrogen isotope permeation. Samples were prepared from joints bonded via solid-state diffusion under hot isostatic pressing (HIP). Deuterium (D) gas permeation tests were performed at various temperatures in the range 400–600 °C at 100 kPa. After deuterium permeation tests, the thermal desorption spectra (TDS) of the samples were analyzed. And the permeation behavior of deuterium atom across the joints was schematically discussed. The results showed that bonding with steel could be an effective solution for resisting hydrogen isotope permeation through the V4Cr4Ti alloy. Thermal desorption spectrum (TDS) analysis of the tested samples revealed a desorption peak temperature equivalent to that of TiC. The formation of a 1 µm-wide B2 ordered α'- [Fe, (V, Ti)] phase layer, together with a large number of dispersed carbides around the interface, played a significant role in the deuterium permeation resistance. In addition, microstructural changes in the steel base material after the 900 °C bonding process were beneficial for suppressing deuterium diffusion.

The behaviors of He atoms at Ti3SiC2(001)/V(110) interface: A first-principles study

Ti3SiC2 nano-particles and He atom play an important role for the degradation of properties in vanadium alloys under irradiation environment. Herein, the behaviors of He atoms at C-Ti2-H Ti3SiC2(001)/V(110) interface model by first-principles calculations, which is the most thermodynamically stable, is studied to elucidate the effect of Ti3SiC2 nano-particles on the He bubble formation in the vanadium alloys. He atom tends to dissolve at the Ti3SiC2/V interface and at the near Si layer of Ti3SiC2 side at the interface. The vacancy type defects formation energies for V1, C1, C2 and Si, which both lower than V monovacancy formation energy in bulk vanadium, are more likely to form at the interface. Moreover, The existence of monovacancy at the interface makes it easier for neighboring He atoms to dissolve, which has a spatial effect on He atom. The result of the trapping energy and the interface distortion of He atom trapped by Si and V1 vacancies, more He atoms can be trapped as the number of vacancies increases. The diffusion of He atom located at Ti3SiC2 side towards the interface hampered by the small spacing Ti and C atom layers (dlsTi2−C2= 1.18 Å) anddlsTi1−C1 = 1.31 Å) He atom tends to aggerate at the interface due to the higher energy barrier. The Ti3SiC2-praticle/V-matrix interface can act as a sink for He atom. These findings provide a new insight into the understanding about the influence of Ti3SiC2 nano-particles on the mechanisms of He bubble formation and the guidance for further the preparation of vanadium alloys.

Deuterium and helium desorption/retention properties of low-activation vanadium alloys possible for reuse in a short time in fusion reactors

Low-activation vanadium (V) alloys are alternative to the reduced-activation ferritic/martensitic steels due to their high-temperature strength, superior irradiation properties and non-magnetic characteristics. To make the reusage of the alloys possible in a short time in fusion reactors, new design concepts of V alloy have been suggested in National Institute for Fusion Science. In the present study, the deuterium and helium retention/desorption behaviors of the new designed V alloys were investigated.A major desorption peak of D2 appeared at 600–750 K for the irradiation at room temperature. This peak would be originated from D atom in a binding state in the alloy. In the case of the irradiation at 773 K, a new peak appeared around 820 K only for the alloy with low purity and high Ti content. Discussion with results of EELS analysis suggests that the desorption around 820 K were originated form D trapped by the precipitates. Other V alloy samples used in the present study showed low D retention for the case of the 773 K irradiation.The helium desorption which was originated from the blisters appeared at the high temperature region. The amounts of these desorption for the alloy with high Ti content was large, compared with the case of low Ti content.

Deuterium permeation of low-activation vanadium alloys possible for reuse in a short time in fusion reactors

Low-activation vanadium (V) alloys are alternative to reduced-activation ferritic/martensitic steels for the blanket structural material. To make the reusage of the alloys possible in a short time, new-design concepts of V alloy have been suggested in National Institute for Fusion Science. In the present study, the deuterium permeation properties of the new-designed V alloys were investigated.The new-designed V-4Cr-4Ti alloy samples with high and low purity, named H44 and L44, respectively, were used. For comparison, the NIFS-HEAT-2 V alloy samples, named NH2 were also used.It was found from the permeation experiments that deuterium permeability coefficient of L44 was smaller than that of NH2, while the permeability coefficient of H44 was comparable with NH2. These results suggest the permeation coefficient of D of the new-designed V alloy was similar to those of the conventional V alloy, if Ti and O content was the same. Estimated activation energies of diffusion and permeation indicated that the permeation behaviors significantly depended on titanium oxides at the surface and in the bulk. Data obtained by a microscope with Auger electron spectroscopy indicated that the concentration and the composition of the oxide must change with air exposure during the maintenance and with hydrogen isotope exposure during the reactor operation. The obtained results suggest these changes of the concentration and the composition result in the change in the permeation characteristics of hydrogen isotopes.

Superconducting transition temperatures of pure vanadium and vanadium-titanium alloys in the presence of dynamical electronic correlations

Superconducting transition temperatures of pure vanadium and vanadium-titanium alloys in the presence of dynamical electronic correlations

Irradiation Hardening and Microstructure Study of MAX-Phase-Dispersion-Strengthened Vanadium Alloy under Self-Ion Irradiation

V-4Cr-4Ti alloy is one of the candidate structural materials for future fusion reactors due to its desirable characteristics. In our previous research, MAX-phase-dispersion-strengthened vanadium alloy (V-4Cr-4Ti-1.5Y-0.3Ti3SiC2), prepared through mechanical alloying, showed excellent thermal stability and creep resistance and was expected to have good radiation resistance. This study investigates the effects of 2.5 MeV V2+ ion irradiation on V-4Cr-4Ti-1.5Y-0.3Ti3SiC2 and V-4Cr-4Ti alloys at 500 °C, with peak damage of 0.8, 3.5, and 6.1 dpa. Transmission electron microscopy and nanoindentation were used to examine the changes in microstructure and hardness before and after irradiation. The microscopic analysis reveals that dispersed nanoparticles maintained good stability under irradiation. Defect clusters grow with increasing irradiation doses in both materials. The nanoindentation results show that V-4Cr-4Ti-1.5Y-0.3Ti3SiC2 has higher initial hardness and lower irradiation hardening, indicating better resistance to radiation hardening than V-4Cr-4Ti. This research serves as a valuable reference for the assessment of the irradiation resistance of Ti3SiC2-dispersion-strengthened V-4Cr-4Ti alloy.

Towards understanding the mechanism of titanium suppressing vacancy clustering/void nucleation in vanadium alloy

The energetics and dynamics of vacancy/vacancyn (Vacn) clusters in presence of Ti in vanadium alloy were systemically investigated by first-principles calculations to elucidate the mechanism of Ti suppressing vacancy clustering/void nucleation. Energetically, Ti can reduce vacancy formation energy and stabilize vacancy/Vacn cluster, and the TimVacn clusters are more stable than alone Vacn over 30 % with m, n = 5, corresponding to the smaller saturated size. Kinetically, mono-/di-vacancy diffusion and vacancy clustering near Ti are predicted by the CI-NEB methods and empirical formula. Vacancy diffusing towards Ti shows a lower barrier of 0.04 eV than 0.39 eV in vanadium and the energy barriers of vacancy migrating towards Ti-Vac complexes decrease gradually and are even close to zero during vacancy clustering. The migration barriers of vacancy dissociating from Ti-Vac complexes are relatively higher, and Ti changes the migration mechanism of di-vacancy from one-step to two-step. Ti significantly reduces vacancy effective diffusivity, and the effective diffusivity decreases with Ti concentration. The present results show that Ti additions provide more nucleation sites of vacancies, forming large numbers of stable small-size complexes and hindering vacancy diffusion, and eventually suppress the formation and growth of large vacancy clusters/voids.

Magnetostrictive energy conversion ability of Iron Cobalt Vanadium alloy sheet: Experimental and theoretical evaluation

The increasing demand for autonomous devices has made the concept of energy harvesting a significant industrial and academic point of interest. In this domain, an ideal magnetostrictive material for converting mechanical vibrations into electrical energy in a cost-effective way (i.e. competing with the price of primary batteries) remains to be determined. Iron-Cobalt-Vanadium (Permendur, Co49-Fe49-V2) is a promising candidate: it is a soft ferromagnetic material with high magnetization saturation, high magnetostrictive coefficients, low price, and good availability. In this study, the experimental magnetic characterization and simulation of Permendur sheets under tensile stress were performed, and their energy conversion capabilities were assessed. The conversion ability was predicted using thermodynamic Ericsson cycles from reconstructed anhysteretic curves. A maximum of 10.45 mJ cm−3 energy density was obtained under a tensile stress of 480 MPa and a magnetic excitation of 5.5 kA m−1. Then, an additional estimation was proposed to account for the hysteresis losses. For this, major hysteresis loops at different stress levels were considered, yielding an energy density of 3.52 mJ cm−3. Finally, experimental Ericsson cycles were performed to prove the feasibility of the conversion and corroborate the energy level predictions.

Inhibition of Ti-rich precipitates and improvement of the irradiation resistance in V-4Cr-4Ti by adding La element

Four kinds of V-4Cr-4Ti-xLa (nominal composition x = 0, 0.1, 0.5, 1.0 wt.%) alloys with different La contents were prepared by vacuum arc melting. Three of them (x = 0, 0.1, 1.0 wt.%) were selected for single He+ (2000 appm for peak concentration) irradiation and sequential He+/V2+ (10 dpa for peak damage) irradiation at 550 °C. The results showed that the addition of La element could refine the grains by forming the second phase La2O3 particles. Moreover, the addition of La element reduced the sum of impurity elements concentration in the alloy, which inhibited the formation of Ti-rich precipitates and affected the vacancy concentration, thus affecting the evolution of He bubbles under different irradiation types. In addition, the V-4Cr-4Ti-1.0La alloy had a lower irradiation hardening after sequential He+/V2+ irradiation, which might be related to the removal of impurity elements. This work provided a reference for the performance optimization of vanadium alloy for fusion reactors.

Plastic deformation mechanisms in BCC single crystals and equiatomic alloys: Insights from nanoindentation

Deformation plasticity mechanisms in alloys and compounds may reveal the material's capacity towards optimal mechanical properties. We conducted a series of molecular dynamics (MD) simulations to investigate plasticity mechanisms due to nanoindentation in pure tungsten, molybdenum, and vanadium body-centered cubic single crystals, as well as the body-centered cubic, equiatomic, random solid solutions (RSS) of tungsten–molybdenum and tungsten–vanadium alloys. Our analysis focuses on a thorough, side-by-side comparison of dynamic deformation processes, defect nucleation, and evolution, along with corresponding stress–strain curves. We also checked the surface morphology of indented samples through atomic shear strain mapping. As expected, the presence of Mo and V atoms in W matrices introduces lattice strain and distortion, increasing material resistance to deformation and slowing down dislocation mobility of dislocation loops with a Burgers vector of 1/2 (111). Our side-by-side comparison displays a remarkable suppression of the plastic zone size in equiatomic W–V RSS, but not in equiatomic W–Mo RSS alloys, displaying a clear prediction for optimal hardening response of equiatomic W–V RSS alloys. If the small-depth nanoindentation plastic response is indicative of overall mechanical performance, it is possible to conceive a novel MD-based pathway towards material design for mechanical applications in complex, multi-component alloys.

Thermodynamic Modeling of the Vanadium Alloy Smelting Process Using a Silicon-aluminum Reducing Agent

The article is devoted to the study of the theoretical aspect of obtaining a vanadium alloy by aluminosilicothermic method. Vanadium pentoxide and converter vanadium slag were studied as charge materials. Silicon-aluminum ferroalloys, such as ferroaluminosilicocalcium, ferrosilicoaluminum and aluminum-silicon-manganese with calcium, will be used as a reducing agent. The chemical composition of the initial vanadium-containing materials and silicon-aluminum reducing agents were studied by the spectral method of analysis. To analyze the aluminosilicothermal reduction of vanadium in the V-Fe-Si-Al-Ca-O system, the method of complete thermodynamic modeling of metallurgical processes was used. Full thermodynamic modeling was implemented in a computer system using the HSC Chemistry software package. As initial data for determining the parameters of thermodynamic equilibrium for the actual composition of the charge for the smelting of vanadium alloys with a stoichiometric consumption of the reducing agent. To analyze the coexistence of phases in a multicomponent system during the aluminosilicothermal reduction of vanadium, a triple phase diagram was constructed for the V2O5-Al-Si system at different isotherms using the «Triangle» program. As a result, the processes of aluminosilicothermal reduction of vanadium in the process of smelting a vanadium alloy using silicon-aluminum reducing agents were studied. The optimal temperature range for vanadium alloy smelting was set. The range is 1650-1850 K. Also, the results of thermodynamic stud

Ten-Year Recycling of Vanadium Alloy in Fusion Reactors

Low-activation characteristics and dominant radioactive isotopes limiting materials recycling were analyzed for a fusion-reactor-grade vanadium alloy, NIFS-HEAT-2. In order to reduce contact dose rate after use in fusion reactors, purification of the base metal vanadium was examined by chemical aqueous separation, electron-beam vacuum melting and zone refining, focusing on the removal of the dominant high-activation impurities, such as Co, Cu, Fe, Nb, Ni and Mo. Based on the measured impurity levels, remote recycling of vanadium alloy is possible within ten years after use in fusion reactors under operation condition with 100 dpa irradiation. Early quasi-hands-on recycling requires further purification and re-design of alloy composition especially with low Ti and high Cr content. The present paper discusses status of material R&Ds for the ten-year recycling and impact on operation of fusion reactors.