Copper-based Alloys Research Articles

Energetics of cobalt alloys and compounds and solute–vacancy binding in fcc cobalt: A first-principles database

Using extensive first-principles density functional calculations, we calculate thermodynamic properties of binary fcc cobalt-based alloys with 25 different solute elements. For each solute element X, we calculate its (a) nearest- and next-nearest-neighbor solute–vacancy binding energy, (b) dilute impurity mixing energy with respect to the equilibrium and hypothetical fcc-based reference states of the solute, (c) enthalpy of formation of cobalt-rich binary ordered compounds in the Co–X system, (d) solubility enthalpy, and other derived quantities. We find that the solute–vacancy binding energies of all the studied solutes in fcc cobalt are positive (indicating favorable binding), in contrast to nickel, aluminum, magnesium, and copper-based alloys, where mid 3d transition metal solutes have unfavorable solute–vacancy binding. We study the physical and chemical effects influencing solute–vacancy binding energy, and find that (a) it correlates broadly with solute size—larger solute atoms possess stronger binding with vacancies—and this is understood in terms of strain relief and secondary next-nearest-neighbor interactions, and (b) it follows a parabolic trend as a function of d-occupancy across the transition metal series—falling to a minimum at the middle of the series—and this is understood in terms of a d-band filling effect. We also find this d-band filling effect in other calculated quantities such as the dilute impurity volumes and dilute impurity mixing energies. To aid in building thermodynamic databases, we tabulate all the calculated thermodynamic quantities, and compare them with experimental phase diagrams data and previous literature, and find good agreement where such data is available.

Electrochemical Stability of Cu–10Al–10Zn, Cu–10Al–10Ni, and Cu–10Ni–10Zn Ternary Alloys in Simulated Physiological Solutions

Copper-based alloys are widely used in the consumer electronics industry for components such as connector contacts, shielding gaskets, and terminals. Nickel silver is a general term for alloys that contain copper, nickel, and zinc. Nickel silver first became popular as a base metal for silver-plated cutlery and other silverware, notably electro-plated nickel silver, jewelery and coins. In this article, the electrochemical stability of Cu–10Ni–10Zn alloy was compared with that of pure copper and two of copper ternary alloys, namely Cu–10Al–10Zn and Cu–10Al–10Ni in synthetic sweat solution, Hank’s solution and in Ringer physiological solution. Corrosion behavior of the different electrodes was investigated using cyclic voltammetry, potentiodynamic polarization, and impedance spectroscopy techniques. The CVs showed peaks concerning the redox reactions for copper. These peaks were assigned to the formation and reduction of copper species. Furthermore, they showed that the copper oxidation was suppressed to a large extent by the presence of Ni and zinc in the alloy composition than the presence of Al and Zn or the presence of Al and Ni elements. Also, the results showed that the Cu–10Ni–10Zn alloy exhibited good corrosion resistance due to the formation of a protective passive film. The electrochemical impedance spectroscopy results indicated that either a duplex film with an inner barrier layer and an outer porous layer or a single passive layer was formed on the surface. The formation of such passive film was discussed, and the different alloy surfaces examined by scanning electron microscopy and subjected to EDAX analysis. The surface analysis has shown the participation of the different alloying elements in the passive film according to the alloy constituents. Addition of Ni decreases the rate of corrosion of the Cu, and the Cu–10Ni–10Zn was found to be the most corrosion-resistant alloy.

Formation of Titanium Carbide Particles from Cu–Ti–C Metal MELT

Background: The relevance of this research is determined by the necessity of developing new hardened and high-conductivity alloys. Therefore, it aims at studying the possibility of producing disperse hardening carbide particles in a metal copper melt directly. Method: Fact Sage v.7.0 SW package (SGTE database) was used for the thermodynamic simulation of phase equilibria. Experimental work to review the results of interactions processes of a copper-titanium alloy and graphite was also conducted. Metal specimens of the Cu-Ti-C system were obtained during the experimental research. The shape and composition of produced non-metal inclusions were determined, while studying the experimental specimens using a scanning-electron microscope and electron microprobe analysis. Findings: A thermodynamic simulation of phase equilibria in the copper corner of the equilibrium diagram of a Cu-Ti-C system under the conditions of a copper-based liquid-alloy available in a temperature range of 1100 to 1500°С was done within the framework of this research. Simulation results are presented as a liquidus surface, specifying areas of existence of phases that are conjugated with the metal melt. According to our simulation, non-stoichiometric titanium carbide of variable composition will be a phase that is in equilibrium with the metal melt against significant titanium concentration in the copper liquid-alloy. It is found that non-metal inclusions in the experimental samples that were obtained under exposure of the metal melt in contact with graphite are represented by titanium carbide particles of the size 5 μm at most. Carbon to titanium ratio in the particles is C/Ti=0.76. No titanium carbides are produced, if the copper-titanium metal melt is poured into a graphite casting form. Improvements: Outputs may be used to analyze technological processes in copper and copper-based alloy production and to develop compositions of alloying compositions for metal matrix composite production.

Tapada da Ajuda (Lisbon, Portugal) Bronze Age pin

ABSTRACTA pin made of a copper-based alloy, found at Tapada da Ajuda (Lisbon, Portugal), a site dated to the beginning of the Late Bronze Age, was analyzed by X-ray fluorescence (XRF) spectroscopy and examined by microscopy. The results of this study and the unusual manufacturing technique of the pin are presented and discussed in this paper. Typology and production technique of this object seem to indicate a Central European origin.

Phase Equilibria in the Copper-Rich Corner of the Cu-Ni-Si-Cr System

Thermodynamic modeling of phase equilibria in the copper-rich corner of the Cu–Ni–Si–Cr system is performed. The "FactSage" software was used for thermodynamic modeling. Isothermal sections of the Cu–Ni–Si–Cr phase diagram with phase existence areas depending on the concentrations of nickel, silicon and chrome are plotted. Reactions between nickel, silicon and chrome, dissolved in a copper melt, are studied experimentally. The samples after crystallization are investigated using scanning electron microscope and X-ray phase analysis. The conditions of silicide formation in as-cast condition are defined. The research results can be used for technology analysis in copper and copper-based alloys production.

Amorphous Copper-Based Alloys: Structure, Technology and Properties

The scientific interest in amorphous and nanocrystalline materials is associated with the expectation of different structural and size effects on the properties of solids, as applied attention due to the possibility of fundamental changes in the properties of polycrystalline materials. Numerous experimental studies indicate the following regularities: the higher the degree of equilibrium of the melt prior to crystallization is, the better quality has a solid metal. In industrial conditions the equilibrium state of the melt is achieved by the technology for heat treatment of the melt. The scientific rationale for this technology is the results of studying the temperature and time dependence of physical properties. The present work describes the analysis of the physical properties of liquid amorphous solder, conducted heat treatment of the melt and the study of the samples mechanical properties in the solid state. Amorphous ribbons obtained by the technology for melt heat treatment, ceteris paribus withstand higher loads in tension, exhibit better ductility and are characterized by high stability of the results. This fact confirms a more uniform material structure.

Effect of Heat Treatment on the Magnetic Properties of a CuMn Alloy

In this paper, we reported the effect of heat treatment on the magnetic properties of Cu 75.8-Mn 24.2 alloy (wt%) alloy. Magnetization measurements were performed by using a vibrating sample magnetometer (VSM) at 300 K temperature. Observations of the magnetization as a function of applied field and temperature were conducted between -10 and 10 T magnetic field ranges at constant temperature. Since the grain size is important in determining the magnetic properties of copper-based alloys, two different grain-sized samples were examined by using ac magnetic susceptibility measurements. The magnetic saturation and the coercivity values for the small-grained sample are found higher than those for the larger-grained sample. The magnetic saturation values at room temperature were found to be approximately 3.63 and 3.22 emu/g for large-grained and small-grained samples, respectively. Details of the morphological properties and chemical composition have also been examined by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. In addition, X-ray diffraction (XRD) observations were performed for the determination of the crystallography of phases.

Прецизионные функциональные материалы – сплавы с эффектом памяти формы на медной основе

Прецизионные функциональные материалы – сплавы с эффектом памяти формы на медной основе

Influence of Heat Treatment on Martensitic Transformations in Copper-Based Alloys with Shape Memory Effect

In the present work the copper base alloys with shape memory effects were characterized. The alloys were subjected to three different heat treatments that promoted changes in characteristics of thermoelastic martensitic transformation (transformation temperatures, thermal hysteresis and enthalpies of transformation). The alloys have their microstructures characterized by optical and scanning electron microscopy. Microhardness tests were performed. Differential scanning calorimetry (DSC) was used to evaluate the transformation critical temperatures of alloy and the transformation enthalpies for each heat treated sample. Thermoelastic properties have changed for each heat treatment. In the micrographs of the heat-treated samples was possible to observe the microstructure of the martensitic phase characteristic. They show the presence of martensite platelets (needles) self-accommodation.

High-strength copper-based alloy with excellent resistance to hydrogen embrittlement

High-pressure components are generally designed with safety factors based on the tensile strength (TS) of the material; accordingly, materials with higher TS permit designed components with thinner walls, which reduce the weight and cost of the parts. However, many high-strength metals are severely degraded by hydrogen. To this point, efforts to develop a high-strength metal with a TS far beyond 1000 MPa and excellent resistance to hydrogen embrittlement (HE) have failed. This study introduces a high-strength metal with an excellent HE resistance, composed of a precipitation-hardened copper-beryllium alloy with the TS of 1400 MPa. Slow strain rate tensile (SSRT) tests of both smooth and notched specimens were performed in 115-MPa hydrogen gas at room temperature (RT). The alloy had a relative reduction in area RRA ≈ 1 and a relative notch tensile strength RNTS ≈ 1, without degradation in either characteristic.

Textured tape substrates from binary copper alloys with vanadium and yttrium for the epitaxial deposition of buffer and superconducting layers

The structure of tapes of binary Cu–0.6 wt % V and Cu–1 wt % Y alloys and texturing process of them in the course of cold deformation by rolling to ~99% and subsequent recrystallizing annealing have been studied. The possibility of achieving the perfect cube texture in thin tapes made from binary copper-based alloys with vanadium and yttrium additions has in principle been shown. This opens the prospect of using them as substrates when manufacturing tapes of second-generation high-temperature superconductors. Optimum annealing conditions for the studied alloys have been determined, which have made it possible to produce the perfect biaxial texture with a content of cube {001}〈100〉 ± 10° grains on the surfaces of textured tapes of more than 95%.

Inverse Calibration Free fs-LIBS of Copper-Based Alloys

Abstract In this work the analysis by Laser Induced Breakdown Spectroscopy (LIBS) technique of copper-based alloys having different composition and performed with fs laser pulses is presented. A Nd:Glass laser (Twinkle Light Conversion, λ = 527 nm at 250 fs) and a set of bronze and brass certified standards were used. The inverse Calibration-Free method (inverse CF-LIBS) was applied for estimating the temperature of the fs laser induced plasma in order to achieve quantitative elemental analysis of such materials. This approach strengthens the hypothesis that, through the assessment of the plasma temperature occurring in fs-LIBS, straightforward and reliable analytical data can be provided. With this aim the capability of the here adopted inverse CF-LIBS method, which is based on the fulfilment of the Local Thermodynamic Equilibrium (LTE) condition, for an indirect determination of the species excitation temperature, is shown. It is reported that the estimated temperatures occurring during the process provide a good figure of merit between the certified and the experimentally determined composition of the bronze and brass materials, here employed, although further correction procedure, like the use of calibration curves, can be demanded. The reported results demonstrate that the inverse CF-LIBS method can be applied when fs laser pulses are used even though the plasma properties could be affected by the matrix effects restricting its full employment to unknown samples provided that a certified standard having similar composition is available.

Multi-Pulse Excitation for Underwater Analysis of Copper-Based Alloys Using a Novel Remote Laser-Induced Breakdown Spectroscopy (LIBS) System.

In this work, the use of multi-pulse excitation has been evaluated as an effective solution to mitigate the preferential ablation of the most volatile elements, namely Sn, Pb, and Zn, observed during laser-induced breakdown spectroscopy (LIBS) analysis of copper-based alloys. The novel remote LIBS prototype used in this experiments featured both single-pulse (SP-LIBS) and multi-pulse excitation (MP-LIBS). The remote instrument is capable of performing chemical analysis of submersed materials up to a depth of 50 m. Laser-induced breakdown spectroscopy analysis was performed at air pressure settings simulating the conditions during a real subsea analysis. A set of five certified bronze standards with variable concentration of Cu, As, Sn, Pb, and Zn were used. In SP-LIBS, signal emission is strongly sensitive to ambient pressure. In this case, fractionation effect was observed. Multi-pulse excitation circumvents the effect of pressure over the quantitative analysis, thus avoiding the fractionation phenomena observed in single pulse LIBS. The use of copper as internal standard minimizes matrix effects and discrepancies due to variation in ablated mass.

Forming a perfect cubic texture in thin copper–yttrium alloy strips during cold rolling and annealing

The structure of strips produced from the Cu–1 wt % Y binary alloy using cold deformation by rolling to the degree of deformation of ~99%, followed by recrystallization annealing, as well as the process of texture formation in these strips, is studied. The possibility of forming a perfect cubic texture in a thin strip made of a binary yttrium-modified copper-based alloy has been shown in principle, which opens the prospect of the use of this alloy to produce substrates for strip high-temperature superconductors of the second generation. The optimum conditions of annealing have been determined, which make it possible to form a perfect biaxial texture in the Cu–1 wt % Y alloy with a content of cubic grains {001}〈100〉 ± 10° on the surface of the textured strip of over 95%.

Manipulating the interfacial structure of nanomaterials to achieve a unique combination of strength and ductility.

The control of interfaces in engineered nanostructured materials has met limited success compared with that which has evolved in natural materials, where hierarchical structures with distinct interfacial states are often found. Such interface control could mitigate common limitations of engineering nanomaterials. For example, nanostructured metals exhibit extremely high strength, but this benefit comes at the expense of other important properties like ductility. Here, we report a technique for combining nanostructuring with recent advances capable of tuning interface structure, a complementary materials design strategy that allows for unprecedented property combinations. Copper-based alloys with both grain sizes in the nanometre range and distinct grain boundary structural features are created, using segregating dopants and a processing route that favours the formation of amorphous intergranular films. The mechanical behaviour of these alloys shows that the trade-off between strength and ductility typically observed for metallic materials is successfully avoided here.

On additional aging-induced hardening of textured ribbon substrates prepared from binary copper-based alloys

The structure and microhardness of textured ribbon substrates made of binary copper-based alloys and annealed in the temperature interval 400–600°C is investigated. The optimal temperature of additional annealing at which the strength of Cu–Fe and Cu–Cr alloys reaches a maximum is determined. From experimental data, recommendations on the optimal deposition temperature of epitaxial buffer layers and superconducting films can be developed.

Дугостійкий електроконтактний матеріал на основі міді для електроапаратури тягового рухомого складу

The article presents laboratory data of the developed Cu−C−ZrO2−TiO2−TiB2 electrocontact material for electrical equipment of traction rolling stock. It has been esstablished that the new material is more wearproof in the comparison with the widely used Cu−W material, it is caused by high softening temperature and the formation of a new material and flaking-off oxides with a weak bond with the foundation. The developed material has low specific electrical and contact resistance, high conductivity, does not require sophisticated equipment for manufacturing, has a long life and can be used in high-current circuits.Microstructure homogeneity, reduced internal porosity due to the evenness of the distribution of arc suppressive additives ZrO2 and TiO2, the reduction of the number and size of the agglomerates in a new composite electrocontact material provide the required physical and mechanical characteristics. The addition of titanium boride into the copper-based alloy allowed obtaining higher strength and casting properties of the original matrix alloy. Besides, graphitized carbon frame impregnated with the given matrix alloy has higher density and strength characteristics.

Study the Microstructures of Nano-Composite Copper/Zirconium Dioxide under the Process of FSW (Friction Stir Welding)

For the first time, the FSW/PP were used in the aluminum alloys that the recent developments in equipment for operation at higher temperatures, the process has also been used for copper base alloys, iron and nickel. Methods Analysis: In this study, a copper plate is used as the base metal, after that by adding ZrO2 ceramic powder to it and using a non-consumable tool for mixing powder in forms one, two and four-pass, Nano-composite Cu/ZrO2 has been created. Then the mechanical properties of the created Nano-composites were examined and compared with the base metal. Also in another part of this study, a sample was prepared with the same conditions but without using ZrO2 powder. And in order to compare with other samples, its properties were studied. Results: The results of abrasion tests, micro-hardness and micro-structure reviews which were done by using optical and electron microscopes showed that incomparison with base metal, a very desirableabrasion and hardness properties are obtained and fine aggregate copper which already has been considered is fully achieved. It should be noted that in the case of a four-pass process along with using powder, the processed composite layer has more uniformity and homogeneity and higher mechanical properties than the base metal and powder-free samples. Based on the results, the maximum amount of hardness is about 160 Vickers which was obtained in four-pass mode and by using the powder, in compared with the base metal hardness which was about 80 Vickers, a twofold increase is shown. The lowest coefficient of friction is associated with the four-pass process sample by using powder, which has the amount of 47/0; it has demonstrated a significant improvement about abrasion propertiesin comparing with the friction coefficient of the base metal which was about 81/0.

Texture and properties of epitaxial substrates for second-generation tape superconductors

Data on the degree of cube texture perfection, magnetic, and strength properties of two groups of alloys, namely, nickel- and copper-based compositions are reported. For all the alloys under study, a certain quantitative ratio of principal texture components in the alloys subjected to cold rolling to 98.6–99.0% degree of deformation was shown to be a criterion for the possibility of preparing a sharp cube texture in tapes in the course of subsequent recrystallizing annealing. Optimum compositions of nickel-based alloys, which are nonmagnetic at a working temperature of superconductor, were found; all copper-based alloys are nonmagnetic at this temperature. The strength properties of recrystallized nickel- and copper-based tapes are substantially higher than those of tapes made of pure metals.

Research of the Interacting Process of Copper-Base Alloys with Leaching Solutions under the Action of Different Physicochemical Factors

Analysis of the current scientific and technical data shows the increased difficulty in innovative solutions development for metal extraction from different kinds of mineral raw materials, due to fundamental change in mineral resources base of metallurgy. Apart from polymetallic ores, complex in chemistry and intractable, the basis for the current mineral resources base is formed by technogenic production waste, so-called recovered materials. The source for nonferrous metals is not only mineral but also recovered materials. The possibility of copper and zinc extraction from recovered materials, particularly from latten, widely-used in technology, has been examined. The article studies influence of different physicochemical factors on the process of dissolution of copper-base alloys by cathode and anode polarization of a sulfur-graphite electrode. It is specified that copper and zinc extraction by cathode polarization is 25 and 30% respectively. During the solution process, copper is oxidized and sulfurized and complex zinc sulfates are formed, which prevent metals from further dissolution. Electrolyte concentration, current density and temperature contribute to metal solubility increase. It is shown that the difference in leach process of metal alloys and polymetallic minerals is connected both with metal alloys’ structure and mechanism of metals’ solution in nonorganic aqua solution. The results of the phase analysis prove that sulfide and copper oxides and hydrated zinc sulfate, i.е., zinc dissolution is made via formation of sulfates.