Copper Alloys Research Articles

Extending the upper limit of volumetric fraction of oxides in ODS-Cu fabricated with internal oxidation via element doping

In general, when the oxide content is controlled within 5 wt%, increasing the content of oxides is crucial for improving the strength, hardness, and wear resistance of oxide dispersion strengthened copper alloy (ODS-Cu). However, the oxide content of commercially available ODS-Cu fabricated with internal oxidation (e.g. Glidcop-60) is limited to 1.1 wt% due to the adverse effects of irregular growth of oxide particles on overall properties when the oxide content increases. In this study, we introduced oxide particles into Cu matrix via internal oxidation of Cu-Al and Cu-Al-Ti alloys using Rhines-pack method. The origin of irregular oxide particles, oxide bands and healing layers formed in the oxidized layer of the ODS-Cu alloys with high oxide content was revealed. Furthermore, it is found that the doping of Ti can effectively suppress the growth of irregular oxide particles and the formation of oxide bands. In the specimens with a Ti/Al molar ratio of 0.28, Ti has a better inhibitory effect on oxide particle coarsening, and this inhibitory effect is more pronounced when ODS-Cu containing higher oxide content. Compared to Cu-0.6 %Al alloy, the average occurrence and length fraction of oxide bands in Cu-0.6 %Al-0.3 %Ti alloy are significantly reduced (by 81 % and 95 % respectively), and the fraction of oxide particles smaller than 20 nm is significantly increased (from 5 % to 76 %). This Ti-doping strategy solves the dilemma in increasing the oxide content in ODS-Cu produced by internal oxidation, and also provides the possibility for industrial production of high oxide volumetric fraction ODS-Cu with internal oxidation.

Synthesis and Photocatalytic Application of Magnetic CoFe2O4/Conjugated Poly(vinyl chloride) Derivative Nanocomposite.

CoFe2O4 has potential for application as a magnetically recoverable visible-light photocatalyst, but its photocatalytic activity is encumbered by the high recombination probability of its photogenerated holes (h+) and electrons (e-). This work was undertaken to boost the photocatalysis of CoFe2O4 through coupling with conjugated poly(vinyl chloride) derivative (CPVC). An easily implementable solvothermal-liquid solid mixing-evaporation of the solvent-pyrolysis method was exploited to synthesize CoFe2O4/CPVC nanocomposites. The photocatalytic capabilities of the products were assessed through photocatalyzing the reduction of Cr(VI) under visible-light (λ > 420 nm). The results demonstrate that the optimal CoFe2O4/CPVC nanocomposite (CoFe2O4/CPVC-2) has markedly heightened photocatalytic activity (3.6 times that of CoFe2O4) and competent reusability and is magnetically recoverable. Furthermore, CoFe2O4/CPVC-2 also shows superior performance toward photocatalytic treatment of the diluted Cr(VI)-containing passivation solution of copper alloys. It is deduced based on the photoelectricity measurement results that the increased photocatalysis of CoFe2O4/CPVC-2 is chiefly attributed to its p-n heterojunction structure, which greatly elevates the h+-e- separation and transfer efficiency. When waste PVC plastic films (replacing the new pure PVC powder) were utilized for the synthesis, the obtained CoFe2O4/CPVC nanocomposite exhibited even better photocatalytic activity (4 times that of CoFe2O4). This work not only has made a new magnetically recoverable, efficient visible-light photocatalyst for decontamination of Cr(VI) in water but also is inspirational for recycling PVC plastic waste to produce high-valued visible-light photocatalysts.

Study on the lubrication performance of the pitcher plant–like textured surface with various parameters

PurposeThis paper aims to enhance lubrication performance of the pitcher plant–like textured surface with various parameters.Design/methodology/approachA pitcher plant–like structure surface is fabricated on the copper alloy, and the lubrication performance of the pitcher plant–like structure with various parameters is evaluated. In addition, the pressure distribution and oil film load capacity of the pitcher plant–like surface are simulated based on Navier–Stokes equations.FindingsWhen the direction of motion aligns with the pitcher plant–like structure, the friction coefficient remains lower than that of the nontextured surface, and it exhibits a decreasing trend with the increasing of the texture width and spacing distance; the lowest friction coefficient (0.04) is achieved with B = 0.3 mm, L = 1.0 mm and θ = 45°, marking a 75% reduction compared to the nontextured surface. Simulation results demonstrate that with the increase in texture width and spacing distance, the oil film load-bearing capacity demonstrates an increasing trend.Originality/valueBionic pitcher plants are prepared on the copper alloy to improve the lubrication performance and wear resistance.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2024-0119/

Microstructural evolution and modified constitutive model of nanoscale Al2O3 dispersion-strengthened copper under high strain rate deformation

The dynamic mechanical properties and behaviors of an oxide dispersion strengthened copper alloy (ODS Cu) are investigated herein within a strain rate range of 1000–5000 s−1 using a split Hopkinson pressure bar to offer theoretical guidelines for potential applications. The mechanisms of plastic deformation and dynamic recrystallization of ODS Cu were studied by analyzing the microstructure evolution during dynamic compression. The results demonstrate that the strain rate sensitivity of ODS Cu exceeds that of pure Cu, which is beneficial for resisting dynamic high-speed impacts. The accumulation of dislocations and generation of an adiabatic temperature rise during high strain rate deformation promote the splitting of the original grains and the formation of dynamically recrystallized grains. The dominant Goss and cube textures transformed into R-cube textures with increasing strain due to the continuous rotation of subgrains and recrystallized grains. By considering the coupled effects of strain and strain rate, the Johnson-Cook model was modified according to the Voce hardening law. The modified Johnson-Cook model exhibits good agreement with the experimental data across a wide range of strain rates. This study provides insight into the dynamic mechanical behavior of ODS Cu.

The Influence of Aging Temperatures on the Microstructure and Stress Relaxation Resistance of Cu-Cr-Ag-Si Alloy

Copper alloys used in connectors rely significantly on stress relaxation resistance as a key property. In this study, a heavily deformed Cu-Cr-Ag-Si alloy underwent aging at varying temperatures, with a subsequent analysis of its mechanical properties and microstructure, with a particular emphasis on understanding the mechanism of improving stress relaxation resistance. As the aging temperature rose, the Cr precipitated into a Cr-Si composite element precipitated phase. Both work hardening and precipitation strengthening played vital roles in enhancing the stress relaxation resistance of the Cu-Cr-Ag-Si alloy, with the latter exerting a more pronounced impact. The notable performance enhancement observed after aging at 450 °C can be attributed to the synergistic effects of work hardening and precipitation strengthening. Following aging at 450 °C, the alloy demonstrated optimal performance, boasting a tensile strength of 495.25 MPa, an electrical conductivity of 84.2% IACS, and a level of 91.12%. These exceptional properties position the alloy as a highly suitable material for connector contacts.

Deformation mechanism and properties evolution of a copper alloy with ultra-high strength after cold drawing and subsequent aging treatment

In this study, the microstructure and properties evolution of Cu-2.7Ti-0.2Fe alloy (wt.%) during cold drawing and subsequent aging treatment were investigated. The grain refinement mechanisms of the samples were analyzed in detail and systematically based on EBSD characterization. Dislocation evolution realized the refinement of grains by promoting the transformation of dislocation walls/cell walls to high angle grain boundaries. The twin-twin/dislocation intersections were another important way of refinement. Strong <100> and <111> fiber textures were formed during drawing, which had the volume fractions of 24.9 % and 55.5 %, respectively, in the sample with true strain of 8.4. The <100> fiber texture was mainly associated with the twinning and dislocation slipping in the high Schmid factor condition, while the decrease in the fraction of <100> fiber texture was mainly attributed to the grain refinement. The wire peak-aged at 380 °C for 2 h achieved excellent comprehensive properties with yield strength of 1596 MPa, tensile strength of 1682 MPa and electrical conductivity of 15.5 %IACS.

Copper Alloys Performance in High-Pressure and Low-Velocity Conditions Using a Custom Tribometer

A custom tribometer was developed to measure friction coefficient and temperature in high-pressure, low-velocity conditions, specifically for studying copper alloys used in sliding bearings for heavy equipment. Using this equipment, two commercial alloys were tested to evaluate friction coefficient, specific wear rate, thermal behavior, and subsurface strain. The results, validated through comparison with reference commercial equipment and uncertainty estimates, met acceptable criteria for tribological tests, with an uncertainty estimate value for the friction coefficient of 0.4%. The tribological tests confirmed the importance of solid lubrication in high-lead bronzes and the high wear resistance of Cu-Al-Ni-Fe alloys, which directly influence temperature, subsurface strain, and respective wear mechanisms.

Jahn-Teller effect and features of divalent copper ion behavior in multicomponent borate crystals

Crystals of YGa3(BO3)4, YAl3(BO3)4, EuGa3(BO3)4 and EuAl3(BO3)4 with copper alloy were studied by electron paramagnetic resonance and X-ray diffraction analysis. The lattice parameters and coordinates of copper-doped boron atoms were determined. The study of EPR spectra showed that copper is in the divalent state and replaces aluminum ions with C2 node symmetry. In YAl3(BO3)4:Cu crystals, a ligand structure exists due to the interaction of copper electrons with yttrium nuclei. The parameters of the spin Hamiltonian describing the behavior of the Cu2+ spectrum have been determined. The deviation of the Z-axis spectra from the C3 axis by 54(1)° is due to Jahn-Teller vibronic interaction and monoclinic distortion. In the EuGa3(BO3)4 crystal, a new spectrum 2 was found, which also belongs to divalent copper but is observed at an excited state 31 cm−1 away from the ground state. Above 70 K, an isotropic EPR line with a width of 450 Gs, g = 2.1, appears and exists up to room temperature.

Copper Alloying Improves the Microbiologically Influenced Corrosion Resistance of Pipeline Steel

Microbiologically influenced corrosion (MIC) has long been a critical issue due to its potential to cause severe damage to equipment and the associated risk of operational failures, leading to significant financial losses. This study investigates the resistance to MIC caused by sulfate-reducing bacteria (SRB) in four types of pipeline steel materials, which are soon to be introduced to the market. Two of these materials have been alloyed with copper during the metallurgical process. The uniform corrosion rates of the copper-alloyed materials were found to be 0.012 ± 0.002 mm/y, 0.060 ± 0.01 mm/y, and 0.010 ± 0.001 mm/y under test conditions of 25 °C, 40 °C, and 60 °C, respectively. In contrast, the unalloyed steels exhibited corrosion rates of 0.370 ± 0.033 mm/y, 0.060 ± 0.01 mm/y, and 0.378 ± 0.032 mm/y, respectively. The data indicate that the copper-alloyed materials demonstrate superior resistance to MIC, as confirmed by corrosion morphology, weight loss measurements, and electrochemical data. These findings suggest that copper alloying can significantly enhance the MIC resistance of steel materials, offering a promising direction for future material development.

Dual Photoactive Species in CuPd for Light‐switched Homo‐coupling of Alkynes in Anaerobic and Base Free Condition

AbstractVarious ratios of CuPd alloy are loaded on C3N4 and utilized as efficient photocatalyst for the light‐switched homo‐coupling of alkynes in anaerobic and base free condition. For the model phenylacetylene reactant, the light‐irradiation promotes the reaction rate from 36.9 % to 99.9 % and the selectivity of 1,3‐diynes from 0 % to 68.7 %. Different supports, solvents and the induction period of the prepared samples show influence on the activity. The action spectra with different light wavelengths demonstrate that both copper phenylacetylide intermediate formed during the reaction and the localized surface plasmon resonance (LSPR) effect of the copper in CuPd alloy are the photoactive species. Through the control experiments, it confirms that these dual photoactive species and the interface between Cu and Pd are essential for efficient light‐switching reaction pathway.

Spark Plasma Sintering of Cu-Ti-Ni Ternary Alloy: Microstructural, Thermal and Electrical Properties

High strength and good conductivity are both critical parameters for copper-based alloys for electrical and other technological applications. This study is aimed to produce copper alloys and metal matrix composites (MMCs) with enhanced physical properties. Cu-Ti-Ni ternary alloys and MMCs samples were sintered at 600 to 700°C using spark plasma sintering (SPS), with a heating rate of 100°C/minutes, uniaxial pressure of 50 MPa, and a holding time of 10 minutes. Scanning electron microscopy (FE-SEM) was used to examine the microstructure, while the relative densities of the composites were obtained via the Archimedes Principle method. A four-point probe and differential thermal analyzer (DTA) obtained electrical resistivity and thermal properties. The results indicated that the sample density nominally increases with sintering temperature but decreases with aluminium nitride additions. The electrical conductivity increases with the sintering temperature and AlN nanoparticle content. Distinct phase changes were observed from the DTA, occurring with the addition of AlN.

Evolution of copper coupons resistance in Enterobacteriaceae strains isolated from high-contact surfaces in hospital.

Metallic copper alloys have gained attention recently as a cutting-edge antibacterial weapon for areas where surface hygiene is crucial. The present study aimed to assess copper coupons (99% Cu) for their potential to decrease the viability of various Enterobacteriaceae strains from inanimate hospital surfaces. This in vitro-experimental study was conducted at the Microbiology Laboratory, Faculty of Natural and Life Sciences and Earth and Universe Sciences, University of Guelma, and Khodja Ahmed Public Hospital Establishment, Algeria, for a period of six months from January to May 2022. A total of 85 samples were collected from patient room door handles and bed rails at the government hospital in Guelma State, from which 12 enterobacterial isolates were obtained. These isolates were evaluated for susceptibility to copper and polyvinyl chloride (PVC) coupons using plate counts to determine bacterial viability after 72 hours of incubation at 37°C or room temperature (25°C). Antibiotic sensitivity testing was then carried out using a modified Kirby-Bauer disc diffusion method. Copper coupons' ability to either select for or create antibiotic resistance is also determined. Copper showed a bactericidal effect after three hours for Serratia odorifera and six hours for Escherichia coli. Whereas it was shown that within three days of selection, 83.33% of Enterobacteriaceae strains are capable of rapidly acquiring Cu resistance. Indeed, the increase in temperature reduced the effects of Cu (p<0.05; Student's t-test). Antimicrobial susceptibility testing revealed that the copper-resistant bacteria were less sensitive than their predecessors. Citrobacter freundii strains showed the highest incidence of multidrug resistance. The most significant findings included widespread resistance to beta-lactams (100%-75%) and chloramphenicol (66.67%). These results suggest that prolonged copper usage may contribute to the development of antibiotic resistance, which could have significant ramifications.

Anodizing of AA2024 Aluminum–Copper Alloy in Citric-Sulfuric Acid Solution: Effect of Current Density on Corrosion Resistance

Al–Cu alloys are widely used as a structural material in the manufacture of commercial aircraft due to their high mechanical properties such as hardness, strength, low density, and tolerance to fatigue damage and corrosion. One of the main problems of these Al–Cu alloy systems is their low corrosion resistance. The purpose of this study is to analyze the influence of anodizing parameters on aluminum–copper alloy (AA 2024) using a bath of citric-sulfuric acid with different anodizing current densities on the thickness, microhardness, and corrosion resistance of the anodized layer. Hard anodizing is performed on AA 2024 Al–Cu alloy in mixtures of solutions composed of citric and sulfuric acid at different concentrations for 60 min and using current densities (i) of 0.03, 0.045, and 0.06 A/cm2. Scanning electron microscopy (SEM) was used to analyze the surface morphology and thickness of the anodized layer. The mechanical properties of the hard anodized material are evaluated using the Vickers hardness test. The electrochemical techniques use cyclic potentiodynamic polarization curves (CPPC) according to ASTM-G6 and electrochemical impedance spectroscopy (EIS) according to ASTM-G61 and ASTM-G106, respectively, in the electrolyte of NaCl at 3.5 wt. % as a simulation of the marine atmosphere. The results indicate that corrosion resistance anodizing in citric-sulfuric acid solutions with a current density of 0.06 A/cm2 is the best with a corrosion current density (jcorr) of 1.29 × 10−8 A/cm2. It is possible to produce hard anodizing with citric and sulfuric acid solutions that exhibit mechanical properties and corrosion resistance similar or superior to conventional sulfuric acid anodizing.

Tribocorrosion properties of NdCl3-modified resin-based polymeric coatings in contaminated lubricating oils

To improve the tribological performance and corrosion resistance of engine bearings exposed to contaminated lubricating oil, polymer coatings containing NdCl3 at concentrations of 3.45 wt%, 5.17 wt%, and 6.89 wt% were developed, respectively. These coatings were applied to the surfaces of copper and aluminum alloys using a liquid spraying technique, aiming to assess their corrosion and wear resistance. Electrochemical experiments showed that the coating with a 3.45 wt% NdCl3 concentration exhibited superior corrosion resistance, as evidenced by the highest self-corrosion potential and polarization resistance. Furthermore, friction tests on the corroded samples revealed that the 3.45 wt% NdCl3 coating also demonstrated the lowest coefficients of friction and wear rates. This is due to the addition of an appropriate amount of NdCl3, which densifies the internal structure of the coating and improves the mechanical properties of the coating, thereby significantly improving its corrosion and wear resistance.

Inhibition of metal corrosion in neutral aqueous solutions by succinic acid salts

The adsorption, protective and passivating effect of sodium succinate and a blend of sodium alkenylsuccinates SKAP-25 on the oxidized surface of copper, copper-nickel alloy MNZh5-1 and low-carbon steel St3 in a neutral chloride solution were studied. The free adsorption energy (–ΔG0a,max) values for all studied metals suggest chemisorption interaction of these organic anion with oxidized metals surfaces: (–ΔG0a,max) for St3 60.2 kJ/mol, for copper 77.4 kJ/mol and for copper alloy 89.3 kJ/mol. Sodium succinate is able to stabilize the passive state of the MNZh5-1 alloy in a neutral chloride buffer solution. On copper, copper alloy and St3, protection against local depassivation is observed up to a certain concentration, above which the protective properties of sodium succinate decrease. Polarization measurements on the air-oxidized surface of low-carbon steel St3 showed that sodium succinate and SKAP-25, as well as their compositions with 2-mercaptobenzothiazole (2-MBT), are able to reduce anodic dissolution currents and increase the local depassivation potential. Corrosion tests of St3 in a 0.01 M NaCl solution proved the advantage of using the composition of SKAP-25 with 2-MBT (7.1:1) in comparison with the individual compound: the degree of protection of St3 at Cinh=7 mmol/L is 99%, and sodium succinate+SKAP-25 (1:1) at Cinh=7 mmol/L is Z=93%.

Experimental Investigation of Strain Rate Influence on Anisotropy of Uniaxial Tensile Mechanical Properties of CuFe2P Alloy Sheet.

Wire crimping, a process commonly used in the automotive industry, is a solderless method for establishing electrical and mechanical connections between wire strands and terminals. The complexity of predicting the final shape of a crimped terminal and the imperative to minimize production costs indicate the use of advanced numerical methods. Such an approach requires a reliable phenomenological elasto-plastic constitutive model in which material behavior during the forming process is described. Copper alloy sheets, known for their ductility and strength, are commonly selected as terminal materials. Generally, sheet metals exhibit significant anisotropy in mechanical properties, and this phenomenon has not been sufficiently investigated experimentally for copper alloy sheets. Furthermore, the wire crimping process is conducted at higher velocities; therefore, the influence of the strain rate on the terminal material behavior has to be known. In this paper, the influence of the strain rate on the anisotropic elasto-plastic behavior of the copper alloy sheet CuFe2P is experimentally investigated. Tensile tests with strain rates of 0.0002 s-1, 0.2 s-1, 1 s-1, and 5.65 s-1 were conducted on sheet specimens with orientations of 0°, 45°, and 90° to the rolling direction. The influence of the strain rate on the orientation dependences of the stress-strain curve, elastic modulus, tensile strength, elongation, and Lankford coefficient was determined. Furthermore, the breaking angle at fracture and the inelastic heat fraction were determined for each considered specimen orientation. The considered experimental data were obtained by capturing the loading process using infrared thermography and digital image correlation techniques.

New Hellenistic Coin Finds from the Baysun and Kugitang Piedmonts, Southern Uzbekistan (season 2018)

Abstract The article presents assemblage of Seleucid and Greco-Bactrian coins found by the Czech-Uzbek archaeological expedition in the frame of a sampling metal detector survey in the upper reaches of Sherabad Darya, from the sites of the Darband Wall, Daganajam, Kurganzol and Iskandar Tepa in 2018. Sixteen specimens, of both silver and copper alloys, which were determined including a very rare Seleukos I (?) coin are assessed not only from the numismatic and historical point of view, but also analysed in terms of elemental composition.

Understanding the passivation layer formed by tolyltriazole on copper, bronze, and brass surfaces

Tolyltriazole (TTAH) is used industrially as a corrosion inhibitor for copper alloys, particularly in organic media. In this study, the morphology and chemistry of the layer formed by TTAH on copper and copper alloys under realistic conditions is investigated, with focus on the effects due to the presence of tin or zinc in the substrates. A combination of X-ray photoelectron spectroscopy (XPS), medium energy ion scattering (MEIS), and scanning transmission electron microscopy (STEM) has been used. It was found that an inhomogeneous metal–organic layer forms on the surface of copper specimens, likely in the form of copper nanoparticles surrounded by CuxTTAy complexes. This layer increases in thickness for at least 30 days. Chemically, the copper species in the layer are initially in the +2 oxidation state, but after longer exposure to TTAH, mostly Cu(I) is observed. In bronze samples, tin does not appear to segregate to the surface layer. In brass samples, zinc is depleted from the bulk and forms a thicker ZnxTTAy layer.

Effect of heat treatment on the microstructure and properties of CuCrZr prepared by laser powder bed fusion

In this paper, CuCrZr alloys were prepared by laser powder bed fusion technique. Under optimum forming process conditions, a relative density of 99.7% was obtained and the specimens were analyzed for microstructure and properties. To enhance the mechanical properties of the copper alloy, the specimens are post-treated using both solution aging and direct aging heat treatments. The variation and influence mechanism of microstructure and mechanical properties, thermal conductivity and electrical conductivity were studied and analyzed. With direct aging heat treatment a large number of Cr nanoprecipitates can be obtained, significantly improving the properties of the alloy. The best synthesis properties obtained at an aging temperature of 450 °C were: microhardness 168.7 ± 3.1 HV, ultimate tensile strength 481.7 ± 7.6 MPa, electrical conductivity 73.9 ± 0.9 %IACS, thermal conductivity 314.3 ± 5.3 W/(m·K).

Research on Alloying Elements' Influence on CuETP-Grade Copper's Mechanical and Electrical Properties.

The continuous industrial development that occurs worldwide generates the need to develop new materials with increasingly higher functional properties. This need also applies to the basic material for electricity purposes, which is copper. In this article, we carry out studies on the influence of various alloying elements such as Mg, In, Si, Nb, Hf, Sb, Ni, Al, Fe, Zr, Cr, Zn, P, Ag, Sc, Pb, Sn, Co, Ti, Mn, Te and Bi on the electrical and mechanical properties of ETP-grade copper. The research involves producing copper alloys using the gravity die casting method with alloy additions of 0.1 wt.%, 0.3 wt.% and 0.5 wt.%. All resulting materials are cold-worked to produce wires, which are subsequently homogenized and annealed. The materials produced in this manner undergo testing to determine their specific electrical conductivity, tensile strength, yield strength, elongation and Vickers hardness (HV10 scale).