Ni-V Alloys Research Articles

Atomic disorder in Ni-V alloys studied using neutron scattering

Atomic disorder in Ni-V alloys studied using neutron scattering

Investigation of Hydrogen Production Performance Using Nanoporous NiCr and NiV Alloys in KBH4 Hydrolysis

Studies of storage and production of hydrogen, which is an alternative to fossil fuels, have been intensified. Hydrogen production from metal borohydrides via catalyst is very attractive because of its advantages, such as controlled production, high hydrogen content, nontoxicity, etc. In this study, the catalytic performances of nanoporous nickel–chromium alloy and nickel–vanadium alloy catalysts prepared with magnetron sputtering in hydrolysis of potassium borohydride, which is a hydrogen storage material, were investigated. Parameters that affected the hydrolysis reaction rate, such as the temperature, the amount of catalyst, and the volume of 0.5 M HCl solution were investigated using response surface methodology. In addition, the prepared catalysts were characterized with XRD and FE-SEM analysis, and the remaining solutions after the reactions were characterized with FE-SEM/EDS analysis. Using response surface methodology, optimum conditions for the maximum hydrogen production rate were determined to be 1.65 g of catalyst, 6% KBH4, 3% NaOH, and 7 mL of 0.5 M HCl at 333 K. Under these conditions, the hydrogen production rates were calculated as 68.9 L·min−1·gcat−1 and 76.5 L·min−1·gcat−1 for NiCr and NiV, respectively.

Containerless Undercooled Melts: Ordering, Nucleation, and Dendrite Growth

Electromagnetic and electrostatic levitation are applied to containerless undercool and solidify metallic melts. A large undercooling range becomes accessible with the extra benefit that the freely suspended drop is accessible directly for in situ observation. The short-range order in undercooled melts is investigated by combining levitation with elastic neutron scattering and X-ray scattering using synchrotron radiation. Muon Spin Rotation (µSR) experiments show magnetic ordering in deeply undercooled Co80Pd20 alloys. The onset of magnetic ordering stimulates nucleation. Results on nucleation undercooling of zirconium are presented showing the limit of maximum undercoolability set by the onset of homogeneous nucleation. Metastable phase diagrams are determined by applying energy-dispersive X-ray diffraction of Ni-V alloys with varying concentration. Nucleation is followed by crystal growth. Rapid dendrite growth velocity is measured on levitation-processed samples as a function of undercooling ∆T by using high-speed video camera technique. Solute trapping in dilute solid solutions and disorder trapping in intermetallic compounds are experimentally verified. Measurements of glass-forming Cu-Zr alloy show a maximum in the V(∆T) relation that is indicative for diffusion-controlled growth. The influence of convection on dendrite growth of Al50Ni50 is shown by comparative measurements of dendrite growth velocity on Earth and in reduced gravity. Eventually, faceting of a rough interface by convection is presented as observed on Ni2B alloys.

Probing the magnetic phases in the Ni-V alloy close to the disordered ferromagnetic quantum critical point with μSR

Zero (ZF) and longitudinal field (LF) muon spin relaxation data of the d-metal alloy Ni1-xVx are presented at several vanadium concentrations x below and above the critical xc ≈ 11 % where long-range ferromagnetic (FM) order is suppressed. The clear single precession frequency observed for Ni, as expected for a homogeneous FM, changes to rather damped osciallation with small V substitution at x = 4 %, confirming magnetic inhomogeneities caused by the less magnetic V environments in the magnetic Ni matrix. Furthermore, local fields and spatial field distributions can be estimated to characterize different inhomogeneous regimes developing with x in the FM phase of Ni1-xVx. In the regime of x = 7 – 10 % a Kubo Toyabe function well describes the low temperature ZF and LF asymmetry data supporting a static Gaussian field distribution. Closer to the quantum critical concentration a single scale static Kubo Toyabe function with one field distribution is not sufficient to describe the muon relaxation. These data indicate that further changes in spatial distributions and dynamics are evolving as expected within the critical regime of a disordered quantum critical point.

Effect of aluminum additions on the microstructure of Ni-V superalloys

The effect of aluminum additions on the microstructure and the phase composition of an Ni-25 at % V alloy is studied. It is shown that the introduction of aluminum into Ni-V alloys decreases their maximum possible high-temperature strength, since an ordering-separation phase transition occurs in the Ni-Al diffusion couple at temperatures slightly higher than 1200°C with the formation of quasi-liquid aluminum atom clusters in the solid solution lattice.

Thermal and electrical properties of Ni-V alloys at high temperatures

We present the results of a complex investigation of the thermal diffusivity, electrical resistivity, thermal conductivity, and additional electrical resistivity of ten Ni-V alloys containing from 1.5 to 15.6 wt % vanadium in a temperature range of 300–1650 K. Conclusions have been made concerning the effect of different mechanisms of conduction-electron scattering on the kinetic and thermal properties of the Ni-V alloys studied.

Study of Thermal Stability of Ni Silicide using Ni-V Alloy

In this paper, thermal stability of Nickel silicide formed on p-type silicon wafer using Ni-V alloy film was studied. As compared with pure Ni, Ni-V shows better thermal stability. The addition of Vanadium suppresses the phase transition of NiSi to <TEX>$NiSi_2$</TEX> effectively. Ni-V single structure shows the best thermal stability compared with the other Ni-silicide using TiN and Co/TiN capping layers. To enhance the thermal stability up to <TEX>$650^{\circ}C$</TEX> and find out the optimal thickness of Ni silicide, different thickness of Ni-V was also investigated in this work.

Interfacial Reactions in Sn-0.7wt.%Cu/Ni-V Couples at 250°C

The Delco process is a major flip chip under-bump metallurgy process and its contact is soldered with the Ni-7wt.%V substrate; there are, however, only a few studies on the interfacial reactions between solders and Ni-V alloys. This study examines the interfacial reactions of the Sn-0.7wt.%Cu alloy with the Ni-7wt.%V, Ni-5wt.%V, and Ni-3wt.%V substrates at 250°C. It is found that the interfacial reactions between Sn-0.7wt.%Cu and Ni-V alloys are different from those between Sn-0.7wt.%Cu and pure Ni. In addition to the formation of the Cu 6 Sn 5 phase, a new Sn-rich phase, denoted the Q phase, is found in the Ni-V substrate couples. Nucleation of the Ni 3 Sn 4 phase is at a much earlier stage and the rates of consumption of Ni are much higher in Ni-V substrate couples than in Ni substrate couples. Knowledge of these different reactions is important for proper assessment of the flip chip products.

나노급 CMOSFET을 위한 Boron Cluster(B18H22)가 이온 주입된(SOI 및 Bulk)기판에 Ni-V합금을 이용한 Ni-silicide의 열안정성 개선

In this paper, the formation and thermal stability characteristics of Ni silicide using Ni-V alloy on Boron cluster (<TEX>$B_{18}H_{22}$</TEX>) implanted bulk and SOI substrate were examined in comparison with pure Ni for nano-scale CMOSFET. The Ni silicide using Ni-V alloy on <TEX>$B_{18}H_{22}$</TEX> implanted SOI substrate after high temperature post-silicidation annealing showed the lower sheet resistance, no agglomeration interface image and lower surface roughness than that using pure Ni. The thermal stability of Ni silicide was improved by using Ni-V alloy on <TEX>$B_{18}H_{22}$</TEX> implanted SOI substrate.

Direct determination of metastable phase diagram by synchrotron radiation experiments on undercooled metallic melts.

The phase selection process during the crystallization of undercooled metallic melts is studied in situ by combining the electromagnetic levitation technique with energy dispersive x-ray diffraction of synchrotron radiation. The crystallization of metastable bcc phase in binary Ni-V alloys was identified. A metastable phase diagram of Ni-V alloy is constructed, which shows the primarily solidifying phase as a function of composition and undercooling. The analysis within nucleation theory emphasizes the important role of metal oxide as a heterogeneous nucleation site controlling the phase selection.

PREPARATION AND CHARACTERIZATION OF BIAXIALLY TEXTURED METALLIC SUBSTRATES FOR HTS COATED CONDUCTORS

CuNi, NiCr, NiV alloys and pure Ni have been processed to obtain metallic substrates for high critical current density YBCO film depositions. High purity alloys were prepared using plasma arc furnace and the material was cold rolled to low thickness tapes. For all the tapes the (100)[001] cube alignment was induced by a primary recrystallization heat treatment after heavy cold rolling (RABITS). Besides the cube texture a good substrate should be smooth, thin, strong, non magnetic, resistant to oxidation, cold workable and low cost. In this work mechanical, magnetic and oxidation resistance properties of the prepared textured substrates were measured and compared.

Epitaxial growth of heterostructures on biaxially textured metallic substrates for YBa2Cu3O7-x tape fabrication

Abstract The paper presents the current status of Ente per le Nuove tecnologie, ĽEnergia e ĽAmbiente research on the processing of high-irreversibility-field superconductor YBa2Cu3O7-x. (YBCO) tapes, useful for power application. A major part of this review is concerned with buffer layer growth, because this is the most important stage in the YBCO thick-film fabrication on biaxially textured metallic substrates. Several architectures are presented: CeO2/Pd/Ni, CeO2/(Ni-V) and CeO2/NiO/(Ni-V). For all the buffer layer structures the top CeO2 film was deposited by pulsed-laser deposition, while the Pd film was grown by electron-beam evaporation. The observed epitaxial orientation is [001]. The properties of a new non-magnetic Ni-V alloy substrate, as well as the preliminary results on superconducting multilayer structures, are also presented. The YBCO film grown on the CeO2/NiO/(Ni-V) configuration has the critical temperature Tc onset of 90.9 K, zero resistance at 86 K and the critical current density Jc =...

Analytical approximation for calculation of the short-range order in disordered alloys with nonpair atomic interactions

We propose the approximation for an analytical description of the short-range order (SRO) in disordered alloys with many-body atomic interactions of arbitrary orders and a radius of action derived through the generalization of the recently elaborated approach [R. V. Chepulskii and V. N. Bugaev, J. Phys.: Condens. Matter 10, 7309 (1998); 10, 7327 (1998)] based on the joint application of the thermodynamic fluctuation method and perturbation theory. As an example, the correctness of a description within this approximation of the Fourier transform of the SRO parameters as a function of temperature and concentration is demonstrated in the case of Ni-V alloy. The obtained data are in excellent agreement with the results of the Monte Carlo simulation. The developed approach may also be followed in studies of magnetics within the framework of the Ising model, of fluids and amorphous materials within the lattice gas model as well as in investigations of the low-dimension lattice systems.

The effect of nonpair atomic interactions on the short-range order in disordered alloys

The high numerical accuracy of the recently developed (Chepulskii R V 1999 J. Phys.: Condens. Matter 11 8645-60) generalized ring approximation for analytical description of the short-range order (SRO) in disordered alloys with many-body atomic interactions of arbitrary orders is revealed through comparison with the corresponding data of the Monte Carlo simulation. It is shown that this accuracy rises with an increase of the characteristic radius of atomic interactions. By the example of both the simplest model systems and Ni-V alloy, we demonstrate that, within the generalized ring approximation, it is possible to describe the phenomenon of the temperature dependence of a position in reciprocal space of the SRO Fourier transform's maximum at temperature independent atomic interactions. The analytical description of the effect of nonpair atomic interactions on the Fourier transform of the SRO parameters is performed in case of Ni-V alloy.

Fabrication and Properties of Epitaxial Buffer Layers on Nonmagnetic Textured Ni Based Alloy Substrates

Biaxially aligned YBCO thick films on oxide buffered metallic substrates is a promising route toward the fabrication of superconducting tapes operating at liquid nitrogen temperature. The role of buffer layer is to reduce the lattice mismatch between the substrate and the YBCO film, to adapt the thermal expansion coefficient, to hamper the diffusion of Ni in YBCO film and to prevent the oxidation of the metallic substrate surface. This paper presents a study regarding CeO 2 buffer layer deposition on a new nonmagnetic (001)[100] textured Ni-V alloy substrates. The deposition of CeO 2 was performed by both pulsed laser ablation and e-beam evaporation techniques. The θ-2θ X-ray diffraction pattern mainly exhibits the (00l) peaks of CeO 2, indicating that the films are epitaxially grown with the c axis perpendicular to the substrate. Rocking curved through the CeO 2 (002) peak have a FWHM of about 6°. The SEM studies have shown that the surface is smooth, continuos and free of cracks. Texture analysis reveals a good in-plane orientation for the ablated CeO 2 film, whereas the electron beam evaporated CeO 2 shows two textures in the growth plane. Further efforts are focused on the deposition of YBCO thick film on the as buffered nonmagnetic metallic substrate.

Internal-nitriding behavior of Ni-V and Ni-3Nb alloys

Ni-2V, Ni-5V, Ni-12V, and Ni-3Nb alloys (w/o)were nitrided in 10 v/o NH3(bal.H2) over the range of 700-1000°C. Thegrowth rates of the reaction zones followed parabolicbehavior for all of the alloys from 700 to 900°C. At 1000°C, Ni-2V andNi-3Nb formed nitride scales, whereas Ni-5V and Ni12Vformed internal-nitride zones. Nitridation ratesdecreased with increasing vanadium content for the Ni-Valloys. VN precipitated in the Ni-V alloys and NbNprecipitated in Ni-3Nb for all exposure conditions inwhich internal nitridation occurred. The precipitatemorphology changed with temperature and distance from the gas-metal surface. The VN and NbNprecipitates were generally small and spheroidal nearthe surface, increasing in size with distance andtemperature. The NbN precipitates became Widmanstattenat higher temperatures and/or increasing distance withinthe nitrided zone. The solubility of nitrogen in pure Niwas determined and found to decrease with increasingtemperature from 700 to 1000°C. Expressions for the diffusion coefficient of nitrogen in nickelwere determined from the measured permeabilities of eachalloy and the nitrogen solubilities in nickel.

Internal-carburizing behavior of Ni-V, Ni-Cr, and Ni-3Nb alloys

Ni-2V, Ni-5V, Ni-12V, Ni-10Cr, Ni-20Cr, andNi-3Nb alloys were carburized in 1.5 v/oC3H6 (bal. H2) over therange 700-1000°C. Carburization of Ni-5V, Ni-12V,Ni-20Cr, and Ni-3Nb obeyed the parabolic rate law. Ni2V and Ni-10Cr, however, formed onlythin carbide scales upon carburizing. Carburizationrates decreased with increased vanadium content fromNi-5V to Ni-12V for all exposure conditions. V4C3 formed throughout the reaction zones of Ni-12V.Cr3C2 formed in the surfaceregions and Cr7C3 formed withinthe interior of Ni-20Cr. NbC precipitated in Ni-3Nbunder all conditions. The precipitate morphology changed with temperature and distance from thegas-metal surface. V4C3 andCr3C2 particles were generallysmall and spheroidal near the surface of Ni-12V andNi-20Cr, respectively, increasing slightly in size with distance from the surface and withincreasing temperature. The vanadium and chromiumcarbides formed intergranular networks toward thereaction fronts. The NbC precipitates were generallylarge and became Widmanstatten at increasing distancewithin the carburized zone of Ni-3Nb. Expressions forthe diffusion coefficient of carbon in nickel from themeasured permeabilities and carbon solubility data were determined. Solubility products weredetermined for all of the carbides formed and found tobe large in comparison with the product of theactivities of the precipitate elements. Wagner's theory of internal oxidation was shown to be anapproximation to the carburization kinetics attemperatures of 900°C or higher.

Interfaces in ordered intermetallics

In this paper, we have examined different types of interfaces that occur between orientational/translational variants generated during the ordering process. This has been illustrated citing examples of ordering of the FCC structure into DO22, Dla and Pt2Mo type structures in some nickel base alloys. Microstructures consisting of more than one ordered structure have also been investigated. Superlattice domains of DO22 and Pt2Mo type structures have also been found to coexist in a microscopic scale of mixing in Ni-V alloys while mixed domains of Dla and Pt2Mo type structures on a much finer scale have been observed in Ni-Mo alloys. The formation of different variants (rotational and translational) of ordered structure(s) from the disordered lattice has been explained on the basis of group theoretical and symmetry considerations.

Mixing enthalpies of liquid Ni-V, Ni-Nb and Ni-Ta alloys measured by levitation alloying calorimetry

Mixing enthalpies have been determined by levitation alloying calorimetry (the LAC method) for the liquid systems Ni-V in the Ni rich range up to x v = 0.48 at 1927 and 2020 K and in the V rich range up to x Ni = 0.4 at 2320 K, for Ni-Nb up to x Nb = 0.4 at 2000 K and for Ni-Ta up to x Ta = 0.31 at 2000 K. The experimental results are successfully described by means of the quasichemical model. A temperature dependence of the mixing enthalpy cannot be found. The location of the minima corroborates the glass forming ability of the systems. The values of the mixing enthalpy have been compared with the available formation enthalpies for the solid compounds of the systems. The comparison shows a good agreement.

Mixing Enthalpies of Liquid Ni-V, Ni-Nb and Ni-Ta Alloys Measured by Levitation Alloying Calorimetry

Mixing enthalpies have been determined by levitation alloying calorimetry (the LAC method) for the liquid systems Ni-V in the Ni rich range up to Xv = 0.48 at 1927and 2020 K and in the V rich range up to XNi = 0.4 at 2320 K, for Ni-Nb up to XNb = 0.4 at 2000 K and for Ni- Ta up to XTa = 0.31 at 2000 K. The experimental results are successfully described by means of the quasichemical model. A temperature dependence of the mixing enthalpy cannot be found. The location of the minima corroborates the glass forming ability of the systems. The values of the mixing enthalpy have been compared with the available formation enthalpies for the solid compounds of the systems. The comparison shows a good agreement. Résumé Les enthalpies de mélange ont été déterminées par calorimétrie pour alliage par lévitation (la méthode “LAC”) pour les systèmes liquides Ni-V dans le domaine riche en Ni jusqu'à Xv = 0.48 à 1927K et Ré 2020 K et dans le domaine riche en V jusqu'à XNi = 0.4 à 2320 K, pour le Ni-Nb jusqu'à XNb = 0.4 à 2000 K et pour le Ni-Ta jusqu'à XTa = 0.31 à 2000 K. Les résultats expérimentaux sont décrits avec succès par le modele quasi-chimique. On n'a pas trouvé de dépendance sur la température de l'enthalpie de melange. L'emplacement des minima corrobore l'habilité des systèmes à former du verre. Les valeurs de l'enthalpie de mélange ont été comparées avec les enthalpies de formation disponibles pour les composés solides des systémes. La comparaison montre une bonne corrélation.