Copper-nickel System Research Articles

Obtaining of Copper- and Nickel-Based Polymetallic Gradient Products by Wire-Feed Electron Beam Additive Manufacturing

The structure and mechanical properties of gradient transition zones of the copper-nickel system formed by additive electron beam technology have been investigated. Pure copper and nickel alloy Ni80Cr20 were used for printing. The data obtained testify to the complex and heterogeneous nature of structure formation when printing both by single-wire method and using double-wire controlled feeding of material into the melt bath. In the samples, the formation of defects of different scale from local inhomogeneities of the structure to pores and cracks is possible. The mechanical properties of the structural gradient zone are at a sufficiently high level and depend on the ratio of the system components.

Analytic description of grain boundary segregation, tension, and formation energy in the copper–nickel system

In this theoretical study, a recently proposed segregation model is applied to segregation data of an exemplary Σ5 grain boundary (GB), which is investigated using a copper–nickel embedded-atom method potential. Segregation in the semi-grandcanonical ensemble is systematically studied by varying the chemical potential in order to explore the full composition range for temperatures from 500 K to 1000 K. As a major thermodynamic feature, the mentioned segregation model avoids the usage of interface compositions, for which an arbitrary volume must be defined, but rather models the thermodynamically unambiguous solute excess. It was shown that the solute excess and the interface formation energy could be described very accurately over a wide range of temperatures and over the entire composition range based on a composition-dependent, but temperature-independent effective energy of segregation. However, the model was initially derived for systems without lattice mismatch so that interface tensions were neglected. Since the copper–nickel system exhibits a moderate lattice mismatch of roughly 2.7%, the copper–nickel system is chosen in this study to further extend the segregation model by a linear-elastic theory to also account for the interface tensions. Using this extended model, it will be shown that the solute excess, GB tensions, and GB formation energies can be derived from the effective energy of segregation for all temperatures and over the whole composition range. As in principle only one single segregation isotherm is sufficient to determine the effective energy of segregation and derived thermodynamic interface quantities, the application of this model is especially interesting for experimental evaluations.

Analytic Description of Grain Boundary Segregation, Tension, and Formation Energy in the Copper-Nickel System

Analytic Description of Grain Boundary Segregation, Tension, and Formation Energy in the Copper-Nickel System

A systematic study of grain boundary segregation and grain boundary formation energy using a new copper–nickel embedded-atom potential

In this atomistic study on the copper–nickel system, a new embedded-atom alloy potential between copper and nickel is fitted to experimental data on the mixing enthalpy, taking available potentials for the pure components from literature. The resulting phase boundaries of the new potential are in very good agreement with a recent CALPHAD prediction. Using this new potential, a high angle symmetrical tilt Σ5 and a coherent Σ3 twin grain boundary (GB) are chosen for a systematic investigation of equilibrium GB segregation in the semi-grandcanonical ensemble at temperatures from 400 K to 800 K. Applying thermodynamically accurate integration techniques, the GB formation energies are calculated exactly and as an absolute value for every temperature and composition, which also enables the evaluation of GB excess entropies. The thorough thermodynamic model of GBs developed by Frolov and Mishin is excellently confirmed by the simulations quantitatively, if the impact of both segregation and GB tension on the change in GB formation energy is accounted for. In the case of the Σ3 coherent GB, it turns out that the change in GB formation energy at low temperatures is for the most part attributed to the GB tension, while segregation only has a small influence. This demonstrated effect of GB tensions should also be taken into account in the interpretation of experiments.

Microwires of nickel, cobalt and copper-based alloys characterized by high level of temperature and time stability

The results of investigations of temperature and time stability of cast microwires in glass insulation from resistive alloys of nickel–chrome, cobalt–chromium and copper–nickel systems are presented. It is established that microwires from the investigated alloys retain their temperature stability at temperatures not lower than 350°C. An investigation of the time stability showed that changes in the electrical resistance during long-term storage of microwires (up to 1 year) do not occur in warehouse conditions, and despite the high degree of nonequilibrium of alloys during high-temperature hardening of the melt, relaxation phenomena are not observed. Consequently, the investigated microwires from alloys based on nickel, cobalt and copper are a very promising material for manufacturing thermostable resistive elements for precision instrumentation.

A Systematic Study of Grain Boundary Segregation and Grain Boundary Formation Energy Using a New Copper-Nickel Embedded-Atom Potential

Abstract In this atomistic study on the copper–nickel system, a new embedded-atom alloy potential between copper and nickel is fitted to experimental data on the mixing enthalpy, taking available potentials for the pure components from literature. The resulting phase boundaries of the new potential are in very good agreement with a recent CALPHAD prediction. Using this new potential, a high angle symmetrical tilt Σ 5 and a coherent Σ 3 twin grain boundary (GB) are chosen for a systematic investigation of equilibrium GB segregation in the semi-grandcanonical ensemble at temperatures from 400 K to 800 K. Applying thermodynamically accurate integration techniques, the GB formation energies are calculated exactly and as an absolute value for every temperature and composition, which also enables the evaluation of GB excess entropies. The thorough thermodynamic model of GBs developed by Frolov and Mishin is excellently confirmed by the simulations quantitatively, if the impact of both segregation and GB tension on the change in GB formation energy is accounted for. In the case of the Σ 3 coherent GB, it turns out that the change in GB formation energy at low temperatures is for the most part attributed to the GB tension, while segregation only has a small influence. This demonstrated effect of GB tensions should also be taken into account in the interpretation of experiments.

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. VI. Copper-nickel system

Phase equilibria and thermodynamics of binary copper systems with 3d-metals. VI. Copper-nickel system

Catalytic properties of monometallic copper and bimetallic copper-nickel systems combined with ceria and Ce-X (X = Gd, Tb) mixed oxides applicable as SOFC anodes for direct oxidation of methane

The present contribution analyses the possibilities of both Cu and bimetallic Cu-Ni formulations combined with CeO 2-based oxides for their use as anodes of solid-oxide fuel cells (SOFC) for direct oxidation of methane. The main objective is related to examining how the metals combination and the presence of dopants like Gd and Tb into the ceria structure could affect the catalytic activity of this type of materials towards reaction with methane. For this purpose, cermets of Cu alone as well as bimetallic Cu-Ni (with 20 and 40 wt.%) have been synthesised in combination with various supports composed by oxides of Ce, Ce-Tb and Ce-Gd. The behaviour of such systems towards interaction with dry methane up to 900 °C was analysed by means of CH 4-TPR tests. Appreciable differences in the catalytic activity are revealed as a function of the presence of nickel as well as Gd or Tb dopants in the systems. The characteristics of carbonaceous deposits formed upon such interaction was analysed by means of TPO and XPS.

Effect of Solid Solution Impurities on Dislocation Nucleation During Nanoindentation

Dislocation nucleation in solid solutions of face-centered-cubic metallic materials was studied using nanoindentation. The effects of solute impurities in the copper–nickel system on the formation of dislocations in a previously dislocation-free region were demonstrated to be minimal. The shear stress required to nucleate dislocations in copper is approximately 1.6 GPa, while in nickel a 3.9 GPa shear stress is required. Changes in shear stress for nucleation track closely with changes in elastic modulus showing the nucleation stress is approximately 1/30 to 1/20 of the shear modulus. The expected solid-solution strengthening is identified within the same experimental method, demonstrating unambiguously the fact that solid-solution impurities in this system will impact the propagation of dislocations during plastic deformation but not alter the homogeneous nucleation of dislocations in these materials.

Investigation of the thermodynamic properties of Cu–Ni alloys obtained by electrodeposition or by casting

The enthalpies of alloy formation in the copper–nickel system have been determined by reaction calorimetry of dissolution at 298 K and it has been shown that this method can be applied for the investigation of electrodeposited alloys, which often are irreversible and representing metastable systems. It has been demonstrated that electrochemical Cu–Ni plating from diphosphate electrolyte under conditions leading to a deposition of a solid copper–nickel solution allows it to produce a thermochemical analogue of a cast alloy. The results obtained indicate that a model of the subregular solution type still provides a reasonable description of the thermodynamic functions in this system. The activity of the components over the entire concentration range was calculated using experimental data and the relationship between partial enthalpy of mixing and partial excess entropy of dissolved components in infinitely dilute solutions.

Effects of diffusion induced recrystallization on volume diffusion in the copper-nickel system

The effects of diffusion induced recrystallization (DIR) on volume diffusion in the Cu(Ni) system was investigated. Cu-Ni diffusion couples annealed at 500, 550, 600, and 650 °C for 120 and 200 h were used to calculate the volume diffusion for the Cu(Ni) binary system. Using characterization techniques such as focused ion beam (FIB) and transmission electron microscopy (TEM), observation of the interdiffusion zone revealed areas containing DIR and non-DIR. The volume diffusion of Ni into Cu across the non-DIR regions were calculated using the Boltzmann-Matano (B/M) method at 1 wt% Ni to be 8.05E-21, 9.88E-20, 4.53E-19, 2.67E-18 m 2/s for 500, 550, 600, and 650 °C, respectively. Calculations of volume diffusion across the DIR zones were approximately three to four orders of magnitude higher than the volume diffusion based on the non-DIR information. Literature values for volume diffusion in the Cu(Ni) system are also higher than the non-DIR values by approximately one order of magnitude, implying that previous values may contain grain boundary contributions.

Selective Removal of Copper from Muitication Dilute Aqueous Solutions Using the Membrane-Electrode Process

ABSTRACT The presence of metallic contaminants (in the form of cations) in wastewater streams has long been a source of concern to process industries. Conventional methods of removal of metallic components from wastewater result in products which have little or no further use and are subsequently Iandfilled (6). This research involves developing a method, i.e., the membrane-electrode (M-E) process, to selectively re-cover heavy metals from dilute aqueous waste streams (cation concentrations less than 1000 ppm) in forms that can be recycled. Preliminary results for copper—nickel systems are presented to demonstrate the selectivity of this new treatment method.

異種物質接合面近傍の電位分布とエアロゾル粒子の沈着

Experimental and theoretical studies have been conducted on the electric field produced by the surface composed of different kinds of materials(copper-polyethylene and copper-nickel systems). Radioactive material, 241Am, was utilized in the measurement of the electric potential profile. The experimental data obtained agreed well with the theoretical results for the copper-nickel system, while the experimental error for the copper-polyethylene system increased with the increase in the distance between radiating material and the test surface.As an alternative method for the measurement of an electric potential profile, insulating oil-bath was used. The experimental results obtained by the second method did not agree with the theoretical results, and a long time was required to obtain the steady state value of the electric potential. It is also confirmed that the deposition of charged aerosol particles was affected by the localized electrostatic field, and the particle charged with positive porality deposited mainly on the nickel surface.

Method of determining the kinetics of infiltration of capillary-porous solids by melts

agglomerate' eutectics," in: Physics of the Strength of Composite Materials [in Russian], Izd. Fiz.-Tekh. Inst., Leningrad (1980), pp. 102-109. ii. S. M. Kats, S. S. Ordan'yan, and V. I. Unrod, "Compressive creep of alloys of the ZrC-ZrB2 and TiC--TiB2 systems," Poroshk. Metall., No. 12, 70-75 (1981). 12. Ya. E. Geguzin, "Investigation into the singering of metal powder mixtures. The copper-nickel system. Isomeric powders," Fiz. Met. Metalloved., ~, No. 3, 406-417 (1956).

Alloy formation during the sintering of molybdenum-chromium powder mixtures

A molybdenum-chromium alloy forms through preferential diffusion of chromium into pure molybdenum, with the formation of a stable molybdenum-base intermediate solid solution, followed, after the disappearance of pure molybdenum, by diffusion of chromium into the intermediate solid solution, resulting in a steady increase in the latter's concentration. The picture of alloy formation in the molybdenum-chromium system differs radically from that in a system exhibiting full intersolubility of components in the solid state, such as the copper-nickel system.

Effects of Surface Hardness and Other Material Properties on Erosive Wear of Metals by Solid Particles

Erosion of a material from a metal surface by the action of impinging SiC particles is studied. In a brief review, it is shown that investigators have correlated erosion wear with several material properties. These include fully annealed properties such as surface hardness, or properties relating to atomic band strength such as modulus of elasticity. In this paper, which studies the erosion wear for a number of pure ductile materials as well as alloys in the copper-nickel system, it is shown that a better correlation with erosion wear is achieved by using the Vickers hardness value of the fully work-hardened surface of the material. This quantity is probably the best material parameter to use in predictions of erosion resistance of metals and in the modelling of the erosion process.

Study of copper-nickel alloy formation on silica supports by the magnetostatic and other methods

Magnetostatic and resonance methods have demonstrated the formation of alloys in several silica-supported copper-nickel systems whose metal loadings were varied between 1 and 10% wt. The preparations studied were obtained by impregnation, ion exchange and coprecipitation techniques. In most systems the metals were believed to be reduced but for samples prepared by impregnation with a metal sulfate some sulfide formation was indicated. In all the bimetallic samples the composition of the alloy particles was found to be nonuniform. The two-phase “cherry” model demonstrated for large particles at temperatures and compositions where the Cu-Ni system is characterized by a miscibility gap, is not found applicable to the much smaller particles in supported Cu-Ni catalysts. Incorporation of a calcination step or reduction of the surface area of the support lowered the degree of dispersion but led to more homogeneous alloys. The conclusions from the magnetic data were confirmed and augmented by X-ray diffraction results, which demonstrated for the precalcined preparations a preferential copper oxide reduction. It is also shown that the preparation of fairly homogeneous supported copper-nickel alloys is assisted by using high relative nickel loadings in those cases where there is an enhanced oxide miscibility prior to reduction.

Interaction of benzene with protium and deuterium on copper-nickel films with known surface composition

Copper-nickel films were prepared by successively depositing the two metals from the vapor and subsequently sintering the films under ultra-high vacuum at 200 °C. The nickel content of the film surfaces could be “titrated” by selective chemisorption of hydrogen. In agreement with expectation all films with overall compositions within the miscibility gap of the copper-nickel system at 200 °C possess an equal surface composition of 23 ± 4 at. % of Ni. Benzene is hydrogenated at a constant rate at a given temperature over these films with equal surface composition, but widely varying overall composition. The activation energy over these alloys is E all = 25 kcal/mole, while E Ni = 12 kcal/mole. The rate of the exchange reactions between benzene and deuterium at 41 °C is, again, constant for alloys of equal surface composition; it is by several orders of magnitude larger than the rate of hydrogenation at the same temperature. The exchange reaction displays a constant multiplicity over the alloys with equal surface composition. The totality of the results presented confirms the model proposed previously on the phase distribution of equilibrated copper-nickel films.

The surface of copper-nickel alloy films: II. Phase equilibrium and distribution and their implications for work function, chemisorption, and catalysis

Free energy calculations show that in the copper-nickel system there is a miscibility gap at low temperatures. The composition of the phases that are characterized by minima of the free energy agrees with experimental data on alloy films prepared at low temperatures by interdiffusion of the two components. From data on the diffusion it is inferred that for compositions within the miscibility gap, equilibrated films consist of crystallites each of which contains a kernel of almost pure nickel, enveloped in a skin of a copper-rich alloy. As the composition of either phase is independent of the over-all composition, the surface properties of these alloys are constant. This is confirmed by experimental data on the work function. The model also appears to be consistent with results on the catalytic activity and the heat of adsorption of hydrogen on granular alloy catalysts, as reported by various investigators.

The surface of copper-nickel alloy films: I. Work function and phase composition

The work function and the phase composition have been measured for copper-nickel alloy films prepared by evaporation and subsequent annealing at 200 °C under ultra-high vacuum. The photoelectric work functions of the alloys are found to be lower than those of the individual spec-pure metals sintered at the same temperature. Over a wide range of over-all composition the work function has a constant value of 4.61 eV. X-ray diffraction shows that in this range the sintered films consist of two phases: A copper-rich alloy coexists with an almost pure nickel phase. The data suggest a wide miscibility gap of the copper-nickel system at low temperatures. As the change in work function upon chemisorption of carbon monoxide is small, it is assumed that in the equilibrated two-phase systems the copper-rich alloy forms the adsorbing surface. Its composition is independent of the over-all composition.