Ni Alloy Foils Research Articles

Periodic ultrasound-assisted electrodeposition of Fe–Ni alloy foil

Periodic ultrasound was introduced into the electroforming process to electrodeposit Fe–Ni foil layers with high properties and low coefficient of thermal expansion that satisfied the requirements for avionics packaging. Electrochemical analysis and morphological testing indicated that periodic ultrasound can sufficiently weaken the stripping effect caused by continuous high-power ultrasonic treatment. Under periodic ultrasonic treatment, applying both high current density and high ultrasonic power in the electroforming system is possible. By adjusting the current density and the duty cycle, Fe–Ni deposits with coefficients of thermal expansion (CTEs) ranging from 2.96 to 6.71 × 10−6/ °C were obtained. Compared to Fe–Ni alloys prepared via traditional electrodeposition methods, the Fe–Ni layers obtained in this study exhibit a larger range of CTE values and great improvements in other physical and mechanical properties. The Fe–Ni alloy foil obtained at a duty cycle of 0.57 and current density of 1 A/dm2 possessed a low surface roughness of 0.95 μm, the iron content of 63 wt.%, micro-hardness of 373.1 HV, Young's modulus of 133.7 MPa, and CTE of 5.39 × 10−6/ °C.

Rapid Electrodeposition of Fe–Ni Alloy Foils from Chloride Baths Containing Trivalent Iron Ions

This work presents the rapid electrodeposition of Fe–Ni alloy foils from chloride baths containing trivalent iron ions at a low pH (<0.0). The effect of the concentration of Ni2+ ions on the content, surface morphology, crystal structure, and tensile property of Fe–Ni alloys is studied in detail. The results show that the co-deposition of Fe and Ni is controlled by the adsorption of divalent nickel species at low current density and the ionic diffusion at high current density. The current density of preparing smooth and flexible Fe–Ni alloy foils is increased by increasing the concentration of Ni2+ ions, consequently the deposition rate of Fe–Ni alloy foils is increased. For example, at 0.6 M Ni2+ ions, the current density can be applied at 50 A·dm−2, along with a high deposition rate of ~288 μm·h−1.

In Situ Vertical Growth of Fe–Ni Layered Double-Hydroxide Arrays on Fe–Ni Alloy Foil: Interfacial Layer Enhanced Electrocatalyst with Small Overpotential for Oxygen Evolution Reaction

Layer double hydroxide (LDH) has been widely applied to electrocatalysis, especially toward the oxygen evolution reaction (OER), owing to its flexible layered structure and multifunctionality. Herein, FeNi LDH nanosheet arrays are directly synthesized on various metal foils by a facile hydrothermal method. Compared with single Fe or Ni substrates, the obtained FeNi LDH/FeNi foil exhibited an ultrasmall onset overpotential of ∼90 mV, high catalytic activity (overpotential of 130 mV @ 10 mA/cm2), and durable stability in 0.1 M KOH electrolyte. We also demonstrate, by utilizing density functional theory calculations, that the growth of the hydroxide interfacial layer between LDH and FeNi foil makes the LDH possess more favorable adsorption to the OH intermediate during OER than the pure LDH. This reveals that the vertical FeNi LDH arrays on the FeNi alloy substrate are prone to be an efficient catalyst toward OER.

Hydrogen isotherms for compositionally homogeneous and inhomogenous Pd1−xNix alloys

Compositional inhomogeneities have been introduced into fcc Pd–Ni alloy foil by arc-melting the pure elements together without annealing either the arc-melted buttons or the resulting cold-rolled foil. Alternatively inhomogeneities have been introduced by subjecting the homogeneous alloy foils to moderately high H2 pressure at moderately high temperatures, hydrogen heat treatment, HHT. The alloys were then progressively annealed in vacuo and H2 isotherms measured after the annealing treatments. The compositional inhomogeneities in the un-annealed alloys are reflected by sloping H2 isotherms in the two phase region and for those subjected to HHT, by lower plateau pressures and by the elimination of hysteresis. Isotherms in the dilute phase region for the alloys prepared from unannealed buttons are largely unaffected by the compositional inhomogeneities. Progressive annealing of the inhomogeneous foils, leads to gradual isotherm changes eventually approaching that characteristic of the well-annealed alloys. The alloys subjected to HHT recovered at lower annealing temperatures than the unannealed buttons and foils. This research should help in the detection of compositional inhomogeneities from the isotherms of other Pd alloys.

Ordered NiO-TiO2 nanotube arrays as an efficient catalyst support for methanol oxidation

Ordered NiO–TiO2 nanotube arrays (NiO–TiO2NTs) were fabricated on titanium–nickel (Ti–Ni) alloy substrate by anodic oxidation of Ti–Ni alloy foil and subsequently investigated as a catalyst support for methanol oxidation. The field emission scanning electron microscopy (FESEM) results demonstrate that NiO–TiO2NTs have the feature of regular tubular structure, which is advantageous to support catalysts for methanol oxidation reactions. The electrochemical results show that Pt nanoparticles supported on NiO–TiO2NTs have similar functionalities as PtNi alloy nanoparticles supported on TiO2 nanotube arrays for methanol oxidation. The NiO–TiO2NTs catalyst support developed here can be easily synthesized and thus show promising application prospect in direct methanol fuel cells (DMFC).

Synthesis of large single-crystal hexagonal boron nitride grains on Cu-Ni alloy.

Hexagonal boron nitride (h-BN) has attracted significant attention because of its superior properties as well as its potential as an ideal dielectric layer for graphene-based devices. The h-BN films obtained via chemical vapour deposition in earlier reports are always polycrystalline with small grains because of high nucleation density on substrates. Here we report the successful synthesis of large single-crystal h-BN grains on rational designed Cu-Ni alloy foils. It is found that the nucleation density can be greatly reduced to 60 per mm(2) by optimizing Ni ratio in substrates. The strategy enables the growth of single-crystal h-BN grains up to 7,500 μm(2), approximately two orders larger than that in previous reports. This work not only provides valuable information for understanding h-BN nucleation and growth mechanisms, but also gives an effective alternative to exfoliated h-BN as a high-quality dielectric layer for large-scale nanoelectronic applications.

Fast and simultaneous growth of graphene, intermetallic compounds, and silicate on Cu–Ni alloy foils

A graphene bilayer was grown on copper–nickel alloy foils (30 at-% Ni: 70 at-% Cu designated as a 30Ni–70Cu) via an inductively coupled plasma–chemical vapor deposition chamber, and was characterized. The first layer fully covered the foil, while there was partial coverage of the second layer. At the same time, the alloy catalyst produced a compound of magnesium silicate in some regions and of copper sulfide in other regions on which a graphene monolayer simultaneously grew without any discontinuity or boundaries of the 1st graphene monolayer between simultaneous growth and graphene-only growth regions. Compared with Cu foils, the alloy foils led to faster growth of the graphene film in graphene-only growth regions, while maintaining the same quality, homogeneity, and thickness uniformity as a monolayer graphene grown on Cu. Raman spectroscopy and scattering demonstrated that the 2D and D bands of the Raman spectra were in the same position for the monolayer graphene on 30Ni–70Cu regardless of the grown regions and for the graphene on the Cu with a full width at half maximum of ∼38 cm−1 ranging from 30 to 55 cm−1 of 2D, and without a D band in the spectra of the graphene monolayer and bilayer. Thus the resulting graphene growth is affected primarily by the Cu catalyst, partly by the compounds grown simultaneously with the graphene monolayer on the foil surface via thermal reactions of the impurities dissolved in the alloy matrix, and partly by the Ni. The quality of the graphene is dependent on the major composition of Cu catalyst in the alloy foils. On the other hands, the alloying element of Ni governs the growth kinetics unless the alloy foils is covered with the intermetallic compounds and silicate.

Growth Mechanism and Controlled Synthesis of AB-Stacked Bilayer Graphene on Cu–Ni Alloy Foils

Strongly coupled bilayer graphene (i.e., AB stacked) grows particularly well on commercial "90-10" Cu-Ni alloy foil. However, the mechanism of growth of bilayer graphene on Cu-Ni alloy foils had not been discovered. Carbon isotope labeling (sequential dosing of (12)CH(4) and (13)CH(4)) and Raman spectroscopic mapping were used to study the growth process. It was learned that the mechanism of graphene growth on Cu-Ni alloy is by precipitation at the surface from carbon dissolved in the bulk of the alloy foil that diffuses to the surface. The growth parameters were varied to investigate their effect on graphene coverage and isotopic composition. It was found that higher temperature, longer exposure time, higher rate of bulk diffusion for (12)C vs(13)C, and slower cooling rate all produced higher graphene coverage on this type of Cu-Ni alloy foil. The isotopic composition of the graphene layer(s) could also be modified by adjusting the cooling rate. In addition, large-area, AB-stacked bilayer graphene transferrable onto Si/SiO(2) substrates was controllably synthesized.

Preparation and Characterization of Iron-Riched Nanocrystalline Fe–Ni Alloy Foil

Preparation and Characterization of Iron-Riched Nanocrystalline Fe–Ni Alloy Foil

Electrodeposition of iron‐enriched nanocrystalline Fe‐Ni alloy foil from chloride‐sulfate solutions

PurposeThe purpose of this paper is to obtain iron‐enriched Fe‐Ni alloy foil on Ti substrates with good quality from a chloride‐sulfate bath used in a normal DC plating mode. The effects of iron content on the hardness, surface morphology and microstructure of the foil were clarified.Design/methodology/approachFe‐Ni alloy foil was prepared by electrodeposition in a chloride‐sulfate based solution. The effects of current density, temperature, stirring rate and sodium propargyl sulfonate concentration on the iron contents of the Fe‐Ni alloy foils were studied. The phase composition and surface morphology with various iron contents were characterized by X‐ray diffraction (XRD) and atomic force microscopy (AFM), respectively. Cathodic polarization curves were used to evaluate the role of sodium propargyl sulfonate (PS).FindingsNanocrystalline Fe‐Ni alloy foil containing up to 64 wt. percent iron can be obtained from a chloride‐sulfate based solution. The foil converts from a face‐centered cubic (fcc) Fe3Ni2 phase to a mixture of fcc and body‐centered cubic (bcc) Fe7Ni3 with increase in iron content from 55.0 wt. percent to 63.5 wt. percent. AFM studies revealed that the foil had a fine grain structure with a roughness of 30 nm and grain size of 30 nm. With iron increasing to 63.5 wt. percent some islands appeared on the surface. This structure was related to the development of a (200) fiber texture in the BCC phase. Sodium propargyl sulfonate accelerates the discharge of nickel and inhibits the discharge of Fe.Practical implicationsThe foil has many industrial applications in the area of memory devices for computers, laser components and precise instruments.Originality/valueThe paper presents a process to produce a foil with iron up to 64 wt. percent from a chloride‐sulfate based solution used in normal DC mode. The dependence of microstructure and surface morphology on iron contents also is presented. Until now, there has been little research or reports on this subject.

Substrate grain size and orientation of Cu and Cu–Ni foils used for the growth of graphene films

Graphene growth on Cu foils by catalytic decomposition of methane forms predominantly single-layer graphene films due to the low solubility of carbon in Cu. On the other hand, graphene growth on Cu–Ni foils can result in the controlled growth of few-layer graphene films because of the higher solubility of carbon in Ni. One of the key issues for the use of graphene grown by chemical vapor deposition for device applications is the influence of defects on the transport properties of the graphene. For instance, growth on metal foil substrates is expected to result in multidomain graphene growth because of the presence of grains within the foil that exhibit a variety of surface terminations. Therefore, the size and orientation of the grains within the metal foil should influence the defect density of the graphene. For this reason, we have studied the effect of total anneal time and temperature on the orientation and size of grains within Cu foils and Cu–Ni alloy foils with a nominal concentration of 90/10 by weight. The graphene growth procedure involves preannealing the foil in a H2 background followed by the graphene growth in a CH4/H2 atmosphere. Measurements of the substrate grain size have been performed with optical microscopy and scanning electron microscopy. These results show typical lateral dimensions ranging from a few millimeters up to approximately a centimeter for Cu foils annealed at 1030 °C for 35 min and from tens of microns up to a few hundred microns for the 90/10 Cu–Ni foils annealed at 1050 °C for times ranging from 45 to 90 min. The smaller grains within the Cu–Ni foils are attributed to the higher melting point of the Cu–Ni alloy. The crystallographic orientation within each substrate grain was studied with electron backscatter diffraction, and shows that the preferred orientation for the Cu foil is primarily toward the (100) surface plane. For the 90/10 Cu–Ni foils, the orientation of the surface of the grains is initially toward the (110) plane and shifts into an orientation midway between the (100) and (111) planes as the anneal time is increased.

Synthesis and Characterization of Large-Area Graphene and Graphite Films on Commercial Cu–Ni Alloy Foils

Controlling the thickness and uniformity during growth of multilayer graphene is an important goal. Here we report the synthesis of large-area monolayer and multilayer, particularly bilayer, graphene films on Cu-Ni alloy foils by chemical vapor deposition with methane and hydrogen gas as precursors. The dependence of the initial stages of graphene growth rate on the substrate grain orientation was observed for the first time by electron backscattered diffraction and scanning electron microscopy. The thickness and quality of the graphene and graphite films obtained on such Cu-Ni alloy foils could be controlled by varying the deposition temperature and cooling rate and were studied by optical microscopy, scanning electron microscopy, atomic force microscopy, and micro-Raman imaging spectroscopy. The optical and electrical properties of the graphene and graphite films were studied as a function of thickness.

Study on thermal behavior of metal foils and numerical analysis of thermal stress for flexible solar cell

Thermal expansion behavior of Al, Ti, Mo, stainless steel and Fe–Ni alloy foils, which could be used for the substrate of flexible solar cells, were studied experimentally using thermomechanical analyzer (TMA). Electroformed Fe–Ni alloy foils and commercially available 50 μm thick Al, Ti, Mo and stainless steel were used for experiment. The thermal stresses and the displacement of solar cell systems consisted of metal foil substrate and virtual CIS top cell were numerically analyzed. Then measured coefficient of thermal expansion of metal foils and reference thermal expansion coefficient of CIS were used to compute the thermal stresses and the displacement of the thin film layers and the substrates of solar cell systems.

Evolution of Crystallographic Texture and Mechanical Properties during Annealing of Nanocrystalline Fe-50%Ni Alloy Foil

The crystallographic texture and mechanical properties were investigated in a nanocrystalline Fe-50%Ni alloy fabricated by using an electrodeposition method. The as-deposited texture was characterized by strong <100>//ND and weak <111>//ND fibre components, and the occurrence of grain growth resulted in the strong development of the <111>//ND fibre components with the minor <100>//ND fibre components. The elastic modulus and hardness were measured by means of a nanoindentation test. The annealing led the specimen to an increase in the elastic modulus and a strong decrease in the hardness. The elastic modului measured were compared with the theoretic predictions based on an elastic self-consistent (ESC) polycrystal model. The theoretical values of the elastic moduli through the thickness direction in the sample were in a good agreement with the experimental results.

The role of dynamic SIMS in process development for high-temperature superconducting wire

Flexible metal substrates for long-length high-temperature superconducting (HTS) wires, typically Ni or Ni-alloy foils, include single or multiple buffer layer coatings to provide chemical barriers for the active HTS layer. Chemical issues abound in these multilayer structures, including both intended and unintended bulk reactions, interlayer reactions (corrosion, interlayer compounds), and interlayer diffusion. These effects are a consequence of subjecting multilayer metal/dielectric structures to the rigors of vacuum processing and ex situ conversion reactions. Data are presented that show the applicability of dynamic SIMS (quadrupole, Cs +) in the development of chemically robust structures for HTS applications.

The role of dynamic SIMS in process development for high-temperature superconducting wire

Flexible metal substrates for long-length high-temperature superconducting (HTS) wires, typically Ni or Ni-alloy foils, include single or multiple buffer layer coatings to provide chemical barriers for the active HTS layer. Chemical issues abound in these multilayer structures, including both intended and unintended bulk reactions, interlayer reactions (corrosion, interlayer compounds), and interlayer diffusion. These effects are a consequence of subjecting multilayer metal/dielectric structures to the rigors of vacuum processing and ex situ conversion reactions. Data are presented that show the applicability of dynamic SIMS (quadrupole, Cs + ) in the development of chemically robust structures for HTS applications.

溶湯急冷法で作製したCu-Al-Ni合金箔の組織と機械的性質

Microstructures, shape memory effect and mechanical properties of melt-quenched Cu-14 mass%Al-4 mass%Ni alloy foils have been investigated. The size of columnar grains was about 5 to 10 μm, and they grew from the surface of foil. The crystal structure of the foils was identified with a DO3 type which was similar to that of the β1 phase (Cu3Al). The shape memory behavior of the melt-quenched foil was observed between the liquid nitrogen temperature (77 K) and room temperature, because the martensite transformation occurred at between 223 and 123 K. The tensile strength of the β1 phase at room temperature was three times as high as that of the martensite phase at 77 K. The brittleness of the specimen was remarkably improved by addition of elements of IVa, Va and VIa groups of the periodic table. Especially, the tensile strength of a Cu-14 mass%Al-4 mass%Ni-1 mass%V alloy foil was found to be about 400 MPa.

Microstructure and segregation in splat-cooled iron-nickel alloy

Several Fe-25 wt% Ni alloy foils were processed through levitation melting and splat-cooling. The microstructural variation observed within the same or different foils was attributed to the large number of combinations of processing variables the most important of which are: dropping temperature, platen velocity and platen surface conditions. In foils obtained by splat-cooling superheated droplets the fine rod-like dendritic structure is usually asymmetrical with respect to the center-plane of the foil and microsegregation is very low. In foils obtained by splat-cooling highly undercooled droplets the bulk undercooled fine rod-like dendritic structure is also asymmetrical with respect to the center-plane of the foil. In the central zone of the specimen a number of high nickel-cored dendrites is embedded in a high nickel matrix which is equiaxed or locally columnar dendritic. The formation of this highly segregated structure may be attributed to the interaction between undercooling, fast cooling and intense fluid flow.