Vanadium Layers Research Articles

Effect of the vanadium layer on the wear resistance of the 1050 aluminum alloy coated by cathodic cage plasma deposition

This study investigated the wear resistance of AA1050 aluminum alloy coated using plasma deposition with a vanadium cathode cage and evaluated the effect of subsequently applying a plasma nitriding process to the coated sample. The treatments were carried out at 400°C for 3 hours. To evaluate the composition, thickness and wear resistance of the layers formed, X-ray fluorescence (XRF), scanning electron microscopy (SEM) and fixed ball micro-abrasive wear tests were applied. The treatments altered the wear mechanisms, with the treated samples also showing the two- and three-body wear modes, compared to the aluminium alloy, which only showed the two-body wear mode. The sample coated using only the cathodic cage deposition technique obtained a greater layer thickness (7.6 μm) and better wear resistance, with a reduction of around 83% in the worn volume compared to the 1050 aluminum alloy. However, the subsequent plasma nitriding process proved to be detrimental to the tribological properties of the coating formed, reducing the layer thickness (3.2 μm) and decreasing wear resistance.

Stacking-dependent Van Hove singularity shifts in three-dimensional charge density waves of kagome metals AV3Sb5 (A = K, Rb, Cs)

Vanadium-based kagomé systems AV3Sb5 (A = K, Rb, Cs) have emerged as paradigmatic examples exhibiting unconventional charge density waves (CDWs) and superconductivity linked to van Hove singularities (VHSs). Despite extensive studies, the three-dimensional (3D) nature of CDW states in these systems remains elusive. This study employs first-principles density functional theory and a tight-binding model to investigate the stacking-dependent electronic structures of 3D CDWs in AV3Sb5, emphasizing the significant role of interlayer coupling in behaviors of the VHSs associated with diverse 3D CDW orders. We develop a minimal 3D tight-binding model and present a detailed analysis of band structures and density of states for various 3D CDW stacking configurations, including those with and without a π-phase shift stacking of the inverse star of David, as well as alternating stacking of the inverse star of David and the star of David. We find that VHSs exist below the Fermi level even in 3D CDWs without π-phase shift stackings, and that these VHSs shift downward in the π-phase shift stacking CDW structure, stabilizing the 2×2×2π-shifted inverse star of David distortions in alternating vanadium layers as the ground state 3D CDW order of AV3Sb5. Our work provides the electronic origin of 3D CDW orders, paving the way for a deeper understanding of CDWs and superconductivity in AV3Sb5 kagomé metals.

Atomistic simulation of the influence of semi-coherent interfaces in the V/Fe bilayer system on plastic deformation during nanoindentation

Semi-coherent interfaces can have a strong influence on the mechanical behavior of bilayer systems, which is seen very clearly under indentation conditions where a well-defined plastic zone interacts directly with the interface. The main aim of this work is to study the influence of a semi-coherent bcc/bcc interface in the V/Fe bilayer system with molecular dynamics (MD) simulations. In particular, the influence of the V layer thicknesses on the apparent hardness of bilayer system is investigated. Our results show that the deformation behavior of pure V and pure Fe resulting from the MD simulations is in good agreement with the literature. Moreover, the MD simulations reveal a significant enhancement of the hardness of V/Fe bilayer system for thinner vanadium layers, resulting from the crucial role of the semi-coherent interface as a barrier to dislocation propagation. This is seen from a detailed analysis of the interaction of mobile dislocations in the plastic zone with misfit dislocations in the interface. Our work shows that dislocation pile-ups at the interface and formation of horizontal shear loops are two key mechanisms dominating the rate and magnitude of plastic deformation and thus contributes to our understanding of mechanical behavior of bilayer systems with semi-coherent interfaces.

Towards Room Temperature Thermochromic Coatings with controllable NIR-IR modulation for solar heat management & smart windows applications

Solar heat management & green air-conditioning are among the major technologies that could mitigate heat islands phenomenon while minimizing significantly the CO2 global foot-print within the building & automotive sectors. Chromogenic materials in general, and thermochromic smart coatings especially are promising candidates that consent a noteworthy dynamic solar radiation Infrared (NIR-IR) regulation and hence an efficient solar heat management especially with the expected increase of the global seasonal temperature. Within this contribution, two major challenging bottlenecks in vanadium oxide based smart coatings were addressed. It is validated for the first time that the NIR-IR modulation of the optical transmission (∆TTRANS = T(T〈TMIT) − T(T〉TMIT) of Vanadium oxide based smart coatings can be controlled & tuned. This upmost challenging bottle-neck controllability/tunability is confirmed via a genuine approach alongside to a simultaneous drastic reduction of the phase transition temperature TMIT from 68.8 °C to nearly room temperature. More precisely, a substantial thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of standard pure VO2 thin films but with a far lower transition temperature, is reported. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control & tunability of the optical transmission modulation in the NIR-IR (∆TTRANS) via the nano-scaled thickness’ control of the intermediate Vanadium layer. In addition, the control of ∆TTRANS is accompanied by a tremendous diminution of the thermochromic transition temperature from the elevated bulk value of 68.8 °C to the range of 27.5–37.5 ºC. The observed remarkable and reversible thermochromism in such multilayered nano-scaled system of V2O5/V/V2O5 is likely to be ascribed to a noteworthy interfacial diffusion, and an indirect doping by alkaline ions diffusing from the borosilicate substrate. It is hoped that the current findings would contribute in advancing thermochromic smart window technology and their applications for solar heat management in glass windows in general, skyscraper especially & in the automotive industry. If so, this would open a path to a sustainable green air-conditioning with zero-energy input.

Ceramic Conversion Treatment of Commercial Pure Titanium with a Pre-Deposited Vanadium Layer

Titanium is characterized by poor wear resistance which restricts its application. Ceramic conversion treatment (CCT) is used to modify the surface; however, it is a time-consuming process. In this work, a thin vanadium layer was pre-deposited on the commercial pure titanium (CPTi) samples’ surface, and it increased the oxygen absorption significantly and assisted in obtaining a much thicker oxide layer than those samples without a V layer at the treatment temperatures of 620 °C and 660 °C. The oxidation of the samples pre-deposited with the V layer had a much higher oxidation rate, and V was evenly distributed in the oxide layer. After CCT, all samples had a low wear volume and stable coefficient of friction in comparison to the untreated CPTi sample. A slightly higher wear area in the wear track was observed on the V pre-deposited samples than those samples without vanadium, especially those with a thicker oxide layer (>4 µm). This might be associated with defects in a thicker oxide layer and insufficient support from a shallower oxygen diffusion zone or hard debris created at the initial stage. Vanadium in the oxide layer reduced the contact angles of the surface and increased the wettability significantly.

Towards Unlocking/Tuning the Mott Transition Temperature in Alkaline-Doped Vanadium Oxide Thermochromic Coatings and Potential Green Air-Conditioning via Room Temperature VxOy-V-VxOy Layered Coatings

In this contribution, we validate for the first time that the near infrared-infrared (NIR-IR) modulation of the optical transmission (DTTRANS = T(T<TMIT) - T(T>TMIT)) of vanadium oxide-based nanomaterials can be controlled or tuned via a genuine approach with a simultaneous drastic reduction of its Mott transition temperature TMIT. More accurately, we report a significant thermochromism in multilayered V2O5/V/V2O5 stacks equivalent to that of pure VO2 thin films but with a far lower transition temperature TMIT. Such a multilayered V2O5/V/V2O5 thermochromic system exhibited a net control or tunability of the optical transmission modulation in the NIR-IR (DTTRANS) via the nano-scaled thickness of the intermediate vanadium layer. In addition, the control of DTTRANS is accompanied by a noteworthy diminution of the Mott transition temperature TMIT from the bulk value of 68.8 °C to the range of 27.5–37.5 °C. The observed peculiar thermochromism in the multilayered V2O5/V/V2O5 is likely to be ascribed to a significant interfacial diffusion or an excessive interfacial stress/strain, and/or to an effective halide (Na, K, Ca) doping. This doping is driven by a significant diffusion from the borosilicate substrate surface towards the V2O5/V/V2O5 stacks. If the upscaling of this approach is validated, the current findings would contribute to advancing thermochromic nanomaterials and their applications in smart windows for managing solar heat and green air-conditioning technologies.

Effect of Vanadium Layer on Microstructure and Properties of TC4 (Ti-6Al-4V)/TiAl (Ti-48Al-2Cr-2Nb) Dissimilar Metals Produced by Laser Additive Manufacturing

Dissimilar metal samples of TC4/TiAl were successfully prepared by laser additive manufacturing (LAM) technology, with pure vanadium as the interlayer. The microstructure, phase composition, element distribution and mechanical properties at the interface of TC4/V and TiAl/V were analyzed by optical microscope (OM), scanning electron microscope (SEM) and backscattering diffraction (EBSD). The experimental results showed that the interface microstructure of TiAl/V is mainly composed of γ, α2 phase and V solid solution. The microstructure of the TC4/V interface is mainly composed of β-Ti and V solid solution. There are no holes, metallurgical defects or microcracks at the above two interfaces, and the interface is bonded well. With the increase in the number of deposition layers, the interface bonding depth increases, and its thickness increases from 30 μm to 80 μm. The mechanical properties tests showed that the tensile strength and elongation of dissimilar metals with two layers of V interlayer TC4/TiAl are the highest, and their values are 483 MPa and 0.35%, respectively. Compared with the one-layer V intermediate layer sample (tensile strength 405 MPa, elongation 0.24%), the tensile strength and elongation are increased by 19.2% and 45%, respectively. The tensile strength and elongation of dissimilar metals in three-layer V interlayer TC4/TiAl are the lowest, and their values are 350 MPa and 0.16%.

Near room temperature tunability of thermochromic VO2 thin films prepared via thermal oxidation method, influence of CO2:N2 gas flux ratios

In this study, we have investigated the thermochromic characterizations of VO2 thin films synthesized by the thermal oxidation method. The oxidation process of a DC sputtered metallic vanadium layer on glass substrates, at 450 °C for 1 h, was carried out in the presence of CO2:N2 gases with different flux ratios of 30:70, 40:60, 50:50, 60:40, and 70:30, respectively. Using CO2, as the oxidizing gas, provides an easy control route for obtaining the VO2 phase among various vanadium oxide phases. The layers were characterized by FESEM, XRD & Raman spectra, sheet resistance vs. temperature (20–120 °C), and UV–Vis–NIR spectra at 25 and 90 °C. The XRD and Raman spectra confirmed all prepared layers have a VO2 polycrystalline structure in monoclinic phase. We found among the studied samples CN30-70 and CN50-50 having desirable optical characteristics of peak visible transmittance of about 55%, with low transition temperatures (Tcr) of ∼42 and 31 °C, and also relatively high amounts of ΔT1700nm, ΔTsol and Tlum,av are good candidates for thermochromic smart windows, both from optical properties and economical fabrication method points of view.

Effect of lanthanum doping on the structure and optical properties of nanocrystalline vanadium pentoxide films prepared by sol–gel method

The structural and optical properties of lanthanum oxide doped nanocrystalline vanadium pentoxide films with the chemical composition xLa2O3-(1-x)V2O5.nH2O (where x = 0.25, 0.50 and 1.0 mol%) prepared by sol–gel method were studied. The XRD analysis also revealed that the (002) line is noticeable in the pure film and gets sharper by the addition of Lanthanum, which indicates a layer of intercalation between the vanadium layers. The average crystallite size decreased with increasing Lanthanum content from 4.45 nm to 3.57 nm. By using double-beam UV–VIS spectrophotometers, the optical properties were studied by measuring the absorption, reflectance and transmittance of the prepared films. Some optical parameters like absorption coefficient α, dispersion energy parameters, refractive index n, optical band gap Eop for various transition mechanisms, real parts and imaginary part of the dielectric constants and effective mass were calculated. The absorption coefficient slightly increases with increasing La content, which can be attributed to the increasing of lattice distortion as a result of crystallite size increasing as indicated in the XRD. The transition mechanism was found to be indirect allowed type with optical band gap Eop increasing relative to the La content. By assuming hydrogen like model, the carrier’s contents N were deduced. The absorption spectrum behavior in visible and UV region suggests a promising solution for solar cells and optical-electronic applications.

Structural evolution of the kagome superconductors AV3Sb5 (A = K, Rb, and Cs) through charge density wave order

The kagome superconductors ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$, ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$, and ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ are known to display charge density wave (CDW) order which impacts the topological characteristics of their electronic structure. Details of their structural ground states and how they evolve with temperature are revealed here using single crystal x-ray crystallographic refinements as a function of temperature, carried out with synchrotron radiation. The compounds ${\mathrm{KV}}_{3}{\mathrm{Sb}}_{5}$ and ${\mathrm{RbV}}_{3}{\mathrm{Sb}}_{5}$ present $2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}2$ superstructures in the $Fmmm$ space group with a staggered trihexagonal deformation of vanadium layers. ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ displays more complex structural evolution, whose details have been unravelled by applying machine learning methods to the scattering data. Upon cooling through the CDW transition, ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ displays a staged progression of ordering from a $2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}1$ supercell and a $2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}2$ supercell into a final $2\ifmmode\times\else\texttimes\fi{}2\ifmmode\times\else\texttimes\fi{}4$ supercell that persists to $T=11$ K and exhibits an average structure where vanadium layers display both trihexagonal and Star of David patterns of deformations. Diffraction from ${\mathrm{CsV}}_{3}{\mathrm{Sb}}_{5}$ under pulsed magnetic fields up to ${\ensuremath{\mu}}_{0}H=28$ T suggest the real component of the CDW state is insensitive to external magnetic fields.

Electronic Structure Evolution from Metallic Vanadium to Metallic VxOy: A NAPPES Study for O2 + V Gas–Solid Interaction

Gas–solid interactions between molecular oxygen and metallic vanadium surfaces and the systematic evolution in the electronic structure of vanadium oxide (VOx) surfaces have been explored in the present work by near-ambient pressure photoelectron spectroscopy (NAPPES). The current article studies the evolution of various oxides of vanadium as a function of partial pressure of O2 (ultrahigh vacuum to 1 mbar), temperature (298–875 K), and the exposure time to oxygen (up to 18 h). Valence-band (VB) and core-level spectral measurements recorded with UV (He–I = 21.2 eV) and Al Kα (1486.6 eV) photons, respectively, show interesting changes. (1) Oxidation is limited to the top layers of vanadium at 298 K and up to a partial pressure of 1 mbar O2. About 50% of vanadium gets oxidized, and the remaining amount exists as metal within the top 10 nm. (2) Metallic vanadium disappears above 625 K, and it is predominantly oxidized to a mixture of V4+ and V5+ oxidation states at a 0.1 mbar partial pressure of O2. Points 1 and 2 suggest the predominantly thermodynamically controlled nature of vanadium oxidation through oxygen diffusion into the subsurface and bulk layers. (3) The Fermi-level (EF) feature observed first at ≥725 K at a 0.1 mbar O2 pressure demonstrates the formation of metallic VO2; however, its metallic nature is preserved even at ambient temperature due to interweaving nanodomains of VOx with VO2. (4) Only partial conversion of surface layers to V5+ (V2O5) along with VO2 and V2O3 (within the probing depth of 8–10 nm by near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS)) was observed even after prolonged heating (18 h) in 1 mbar O2 pressure. (5) The nature of the surface changes between metal and semiconducting/insulator oxides is substantiated by the observation of changes in work function (ϕ) and EF features. Typical VB features and Fermi intensity of V-metal and vanadium oxides were observed, and the results were corroborated with core-level and VB spectra. The present results extend the capabilities of NAPPES to explore the electronic structure evolution as a function of reaction conditions and underscore its relevance to areas such as heterogeneous catalysis and sensing.

2D Non‐Van Der Waals Transition‐Metal Chalcogenide Layers Derived from Vanadium‐Based MAX Phase for Ultrafast Zinc Storage

AbstractAlthough 2D non‐van der Waals (vdW) layers show many intriguing physical and chemical properties as well as wide applications in the fields of electronics, catalysis, and energy storage, they still lack efficient synthetic approaches owing to their three‐dimensionally bonded structures. Here, a facile approach to produce 2D non‐vdW transition‐metal chalcogenide (TMC) layers based on the conversion of vanadium‐based MAX phase (V2GeC) at high temperatures in hydrogen sulfide gas is developed. Associated with the etching of the germanium layers from the MAX phase, the vanadium layers are transformed into 2D non‐vdW V3S4 layers. This originates from the self‐intercalation of ordered V atoms within the vdW space of intermediated vdW vanadium disulfide layers during the conversion reaction. Owing to the ultrathin character, highly exposed active surface, and unique vacancy‐enriched structure, the resultant 2D non‐vdW V3S4 layers deliver a high reversible capacity of 341 mAh g−1, good rate capabilities, and long‐term cycling performance for zinc storage.

Influence of deuterium-induced volume changes on optical transmission in Fe/V (001) and Cr/V (001) superlattices

The deuterium-induced changes of the optical transmission in Fe/V (001) and Cr/V (001) superlattices are found experimentally to be dominated by the volume changes of the vanadium layers and thus indirectly linked to concentration. The deuterium-induced expansion is 67% larger in Cr/V 2/14 monolayers (ML) as compared to Fe/V 2/14 ML. This large difference can be explained by a difference in the site of deuterium from tetrahedral in Fe/V to octahedral in Cr/V. First-principles calculations based on this assumption give quantitative agreement with both the measured optical transmission and the deuterium-induced expansion coefficient. Placing hydrogen in the middle of the vanadium layers results in total energies at 0 K that favor tetrahedral occupancy at low concentrations, although the energy difference is of the order of the thermal energy available in the experiments. Hence small changes in strain, defect concentration, and/or vibrational spectrum of the superlattices may tip the balance to octahedral occupancy at low concentrations. Given this link to concentration and the linear scaling, optical transmission can, therefore, be used in a straightforward way to obtain pressure-composition isotherms also in thin metal films that do not undergo metal-insulator transitions upon hydrogenation.

V-V Dimerization and Magnetic State of Cobalt Ions in Ilmenite-Type CoVO3.

The nature of chemical bonds determines the electronic and magnetic properties of compounds. A metal-metal bonding (V-V dimer) and its effect on the magnetism of ilmenite-type CoVO3 were studied. Polycrystalline CoVO3 samples were synthesized using a high-pressure synthesis method. Crystal structure refinement revealed that V-V dimers exist at temperatures below 550 K in the vanadium layers. Co2+ in CoVO3 exhibits an S = 3/2 state, whereas a Jeff = 1/2 state was reported in ilmenite-type CoTiO3. The existence of V-V dimers reduces the structural symmetry (from R3 to P1), which can change the magnetic ground state.

Combined Light and Electron Scattering for Exploring Proximity Effects on Hydrogen Absorption in Vanadium

We investigate proximity effects on hydrogen absorption in ultra-thin vanadium layers through combing light transmission and electron scattering. We compare the thermodynamic properties of the vanadium layers, which are based on the superlattice structure of Cr/V (001) and Fe/V (001). We find an influence of the proximity effects on the finite-size scaling of the critical temperatures, which can be explained by a variation of dead layers in the vanadium. In addition to this, the proximity effects on hydrogen absorption are also verified from the changes of excess resistivity.

Enhanced quasi-monoenergetic ions generation: Based on gold nanoparticles application in gas-filled nanosphere targets

It was recently shown that nanostructured targets with largely spaced gold ultrasmall nanoparticles (NPs) show outstanding performances in enhancing the laser-driven ions' acceleration process due to the higher laser-to-target energy absorption [Vallières et al., Phys. Rev. Accel. Beams 22, 091303 (2019)]. Based on this structure, here, an alternative nanostructured design is proposed to promote light/heavy ions' acceleration quality. The scheme relies on using a gold NP layered nanosphere filled with a low-density argon gas. The nanosphere has an inner layer of vanadium and an outer layer of proton–carbon (1:1) mixture. The validity of this suggestion has been simulated by the two-dimensional particle-in-cell code (EPOCH). Simulation results indicate that the interaction of ultra-intense laser (∼4.61 × 1019 W/cm2) with a gas-filled gold NP layered nanosphere can positively decrease the aggregation of electrons stated inside the target, leading to higher Coulomb repulsion between charged ions. Therefore, we can expect the generation of quasi-monoenergetic H+, C6+, V20+, and Au49+, as well as Ar15+ (cutoff energy of ∼0.49 MeV/u and relative divergence angle of 2.9°) at the end of the interaction. From simulations, as the interaction terminates, for a gas-filled gold NP layered nanosphere with an optimal gap space of 80 nm, a cutoff energy increase of roughly 19% for H+, 16.4% for C6+, and rather equal percent of 15.9% for medium-heavy ions (V20+ and Au49+) is obtained with respect to a hollow gold NP layered nanosphere. Moreover, a relative divergence angle decrease of up to nearly 0.29–1.91 times will be calculated for the accelerated ions. Overall, the results verify that a gas-filled gold NP layered nanosphere can be regarded as a candidate for the generation of quasi-monoenergetic ions through the spherical Coulomb explosion regime.

Analyzing metallurgical interaction during arc surfacing of barrier layers on titanium to prevent the formation of intermetallics in titanium-steel compounds

This paper considers a possibility to obtain high-quality butt junctions of bimetallic sheets from steel clad with a layer of titanium, with the use of barrier layers. The task that was tackled related to preventing the formation of Ti-Fe intermetallic phases (IMPs) between the steel and titanium layer. The barrier layers (height ~0.5 mm) of vanadium and copper alloys were surfaced by arc techniques while minimizing the level of thermal influence on the base metal. To this end, plasma surfacing with a current-driving wire and pulsed MAG surfacing were used. The obtained samples were examined by methods of metallography, X-ray spectral microanalysis, durometric analysis. It has been established that when a layer of vanadium is plated on the surface of titanium, a defect-free structure of variable composition (53.87–65.67) wt % Ti with (33.93–45.54) wt % V is formed without IMPs. The subsequent surfacing of steel on a layer of vanadium leads to the formation of eutectics (hardness up to 5,523 MPa) in the fusion zone, as well as to the evolution of cracks. To prevent the formation of IMPs, a layer of bronze CuBe2 was deposited on the surface of vanadium. The formed layer contributed to the formation of a grid of hot cracks. In the titanium-vanadium-copper transition zones (0.1–0.2 mm wide), a fragile phase was observed. To eliminate this drawback, the bronze CuBe2 was replaced with bronze CuSi3Mn1; a defect-free junction was obtained. When using a barrier layer with CuSi3Mn1, a defect-free junction was obtained (10–30 % Ti; 18–50 % Fe; 5–25 % Cu). The study reported here makes it possible to recommend CuSi3Mn1 as a barrier layer for welding bimetallic sheets "steel-titanium". One of the applications of the research results could be welding of longitudinally welded pipes of main oil and gas pipelines formed from bimetallic sheets of steel clad with titanium.

Fast-ion conduction and local environments in BIMEVOX.

The energy landscape of the fast-ion conductor Bi4V2O11 is studied using density functional theory. There are a large number of energy minima, dominated by low-lying thermally accessible configurations in which there are equal numbers of oxygen vacancies in each vanadium-oxygen layer, a range of vanadium coordinations and a large variation in Bi-O and V-O distances. By dividing local minima in the energy landscape into sets of configurations, we then examine diffusion in each different layer using ab initio molecular dynamics. These simulations show that the diffusion mechanism mainly takes place in the 〈110〉 directions in the vanadium layers, involving the cooperative motion of the oxide ions between the O(2) and O(3) sites in these layers, but not O(1) in the Bi-O layers, in agreement with experiment. O(1) vacancies in the Bi-O layers are readily filled by the migration of oxygens from the V-O layers. The calculated ionic conductivity is in reasonable agreement with the experiment. We compare ion conduction in δ-Bi4V2O11 with that in δ-Bi2O3. This article is part of the Theo Murphy meeting issue 'Understanding fast-ion conduction in solid electrolytes'.

Structural Changes in Surface Layers of Vanadium Induced by the Separate and Sequential Impact of Helium Ions and Pulsed Laser Radiation

Structural Changes in Surface Layers of Vanadium Induced by the Separate and Sequential Impact of Helium Ions and Pulsed Laser Radiation

Fatigue analysis of TI6AL4V/INCONEL 625 dissimilar welded joints

Offshore and oil & gas industries have shown the interest toward the use of dissimilar metals, so there is the problem of their joining. The aim of this research activity was to analyze the fatigue behaviour of Ti6Al4V/Inconel 625 (Nickel alloy 625) welded joint, obtained by laser welding. The investigated joint was obtained including intermediate layers of Vanadium and AISI 304 stainless steel to enhance the mechanical properties. The experimental results in terms of fatigue strength demonstrated a good quality of the obtained joints. The temperature of the specimens during the fatigue tests was detected by means of an Infrared Camera for applying the Thermographic Method and assessing the fatigue strength. The value of the fatigue strength predicted by the Thermographic Method shows a good agreement with the value obtained from the traditional procedure.