Evolution Of Cu Research Articles

Evolution of Cu and Zn speciation in agricultural soil amended by digested sludge over time and repeated crop growth

Metals such as Zn and Cu present in sewage sludge applied to agricultural land can accumulate in soils and potentially mobilise into crops. Sequential extractions and X-ray absorption spectroscopy results are presented that show the speciation changes of Cu and Zn sorbed to anaerobic digestion sludge after mixing with soils over three consecutive 6-week cropping cycles, with and without spring barley (Hordeum vulgare). Cu and Zn in digested sewage sludge are primarily in metal sulphide phases formed during anaerobic digestion. When Cu and Zn spiked sludge was mixed with the soil, about 40% of Cu(I)-S phases and all Zn(II)-S phases in the amended sludge were converted to other phases (mainly Cu(I)-O and outer sphere Zn(II)-O phases). Further transformations occurred over time, and with crop growth. After 18 weeks of crop growth, about 60% of Cu added as Cu(I)-S phases was converted to other phases, with an increase in organo-Cu(II) phases. As a result, Cu and Zn extractability in the sludge-amended soil decreased with time and crop growth. Over 18 weeks, the proportions of Cu and Zn in the exchangeable fraction decreased from 36% and 70%, respectively, in freshly amended soil, to 28% and 59% without crop growth, and to 24% and 53% with crop growth. Overall, while sewage sludge application to land will probably increase the overall metal concentrations, metal bioavailability tends to reduce over time. Therefore, safety assessments for sludge application in agriculture should be based on both metal concentrations present and their specific binding strength within the amended soil.

Effects of temperature on the microstructural evolution and mechanical properties of copper − bearing medium manganese steel during tempering

This work introduced the effects of higher tempering temperatures on the microstructural evolution of Cu − bearing medium Mn steel. After quenching steel at 860 °C for 1 h, it was tempered at 600, 640, and 670 °C for 2 h. The results indicated that the low − temperature impact toughness initially increased and then decreased, while the yield strength consistently decreased with increasing temperature. At a tempering temperature of 640 °C, the steel exhibited a relatively high content of reversed austenite and demonstrated the best low − temperature toughness and plasticity. The low − temperature toughness and plasticity of the steel significantly diminished, when the temperature exceeded 640 °C. This is because the degree of alloying element enrichment in the reversed austenite is reduced, accompanied by an increase in dislocation density and the formation of twins. These reversed austenites exhibit a diminished ability to hinder crack nucleation and propagation. The yield strength decreased with increasing temperature, primarily due to the coarsening of the Cu particles, which reduces their precipitation strengthening effect. This study advances the development of high − strength tough medium − manganese steels.

Effect of Cr Content on Hot Deformation Behavior and Microstructure Evolution of Cu–Cr–Ni Bridge Weathering Steel

The hot compression tests (T = 850–1100 °C, = 0.1–10 s−1) of Cu–Cr–Ni bridge weathering steel with different Cr content (0.46% (#1), 0.64% (#2)) were performed on Gleeble‐3800‐D thermomechanical simulator. The effects of Cr content on hot deformation and microstructure evolution are systematically investigated by the Arrhenius constitutive equation, processing map, electron backscatter diffraction technology, and transmission electron microscope. In the results, it is demonstrated that the increase of Cr content from 0.46% to 0.64% enhances the solution strengthening and inhibits the dynamic recrystallization of the experimental steels during hot compression, resulting in the increase of flow stress. The Arrhenius constitutive equation with strain compensation is constructed. The increase of Cr content results in an augmentation of hot deformation activation energy, rising from Q#1 = 358.47 kJ mol−1 to Q#2 = 396.79 kJ mol−1, causing the increase of deformation resistance of Cu–Cr–Ni bridge weathering steel in hot compression. The optimal hot processing window of #1 and #2 experimental steels is as follows: = 0.1–0.2 s−1, T = 1050–1100 °C, = 0.1–0.15 s−1, and T = 1050–1100 °C, the increase of Cr content leads to the narrowing of the hot processing window of the experimental steels.

Microstructure evolution and mechanical properties of Cu–9Ni–6Sn alloy during continuous cold deformation process

A Cu–9Ni–6Sn alloy bar with pronounced axial columnar grains and a diameter of 10.5 mm was fabricated by using directional solidification technology, which was directly cold-drawn into a superfine alloy wire with a diameter of 40 μm without intermediate annealing. The strength and microstructure evolutions of the Cu–9Ni–6Sn alloy during the cold drawing were studied. The results indicate that twinning is more likely to occur in fiber structures ranging from 60 to 120 nm. A dual-fiber structure consisting of <111> and <100> orientations formed after cold-drawing. Unexpectedly, a large number of deformation twins were discovered within the <111> fibrous texture and later transformed into detwinning structures, disrupting the axial fibrous texture. The generation of deformation twinning primarily results from Ni and Sn elements disrupting crystal symmetry and reducing stacking fault energy of the alloy and the formation of <111> texture. The combined effects of detwinning structures and dislocation wall induced work-softening of the alloy, enabling high-strain processing and ultimately yielding nanocrystalline grains, i.e., the Cu–9Ni–6Sn alloy underwent cold drawing with a high train of 11.23 and obtained an average grain size of ∼38 nm, which exhibited a tensile strength of 1453 MPa.

Microstructure and texture evolution of Cu–Cr–Co–Ti alloys during the two-stage cryorolling

Microstructure and texture evolution of Cu–Cr–Co–Ti alloys during the two-stage cryorolling

Simultaneous Cu(II)-EDTA decomplexation and Cu(II) recovery using integrated contact-electro-catalysis and capacitive deionization from electroplating wastewater

The complex of heavy metals and organic acids leads to high difficulty in heavy metals separation by traditional technologies. Meanwhile, alkaline precipitation commonly used in industry causes the great consumption of resources and extra pollution. Herein, the effective decomplexation of Cu(Ⅱ)-EDTA and synchronous recycling of Cu2+ were realized by contact-electro-catalysis (CEC) coupled with capacitive deionization (CDI) innovatively. In particular, fluorinated ethylene propylene (FEP) as dielectric powders could generate reactive oxygen species under ultrasonic stimulation, realizing continuous deaminization and decarboxylation of Cu(Ⅱ)-EDTA and accelerating the totally breakage of Cu-O and Cu-N bonds. Additionally, the degradation pathway and intermediates evolution of Cu(Ⅱ)-EDTA were investigated using various characterization methods. It was confirmed that decarboxylation predominantly governed the degradation process of Cu(Ⅱ)-EDTA in CEC. During the course of treatment, the degradation ratio of Cu(Ⅱ)-EDTA reached 86.4 % within 150 min. Impressively, this strategy had satisfactory applicability to other metal combinations and excellent cycle stability. Subsequently, the released Cu ions were captured by CuSe cathode electrode through CDI. This research elucidated the degradation mechanism of persistent organic pollutant during CEC, and provided a novel approach for efficiently treating industrial wastewater containing metal complexes and advancing the exploitation and utilization of new technologies for metal recovery.

The exploration of relationship between the evolution of Cu to Cu2O/CuO and photocatalytic efficiency toward water oxidation reaction

This paper introduces a facile method to develop core-shell nanocomposite Cu/(Cu2O/CuO) through gradually oxidation on Cu nanocomposite precursors. As-prepared catalyst exhibited excellent catalytic activity in the reaction of water oxidation reaction (WOR). Comparing with the reported catalyst, Cu/(Cu2O/CuO) posed one of the highest O2 evolution around 7700 μmol g-1·h-1. By analyzing the composition of catalysts in each reaction stages, the evolution pathway of Cu towards Cu2O/CuO and the different roles of each component in catalytic water oxidation reactions were deeply studied. In presence of high conductive Cu element and excellent light absorption Cu2O, the photo generated electron and holes can be effectively separated and greatly improve the efficiency of the catalyst. The evolution process and synergistic effects of the three components play a crucial role in improving photocatalytic efficiency, which promoting the nanocomposite to be a highly efficient core-shell catalyst for WOR.

Precipitation behavior and properties change of Cu–3Ti–2Ni alloy during aging process

The microstructural evolution of Cu–3Ti–2Ni alloy under primary and secondary cold rolling combined aging was investigated through various characterization techniques including transmission electron microscopy (TEM), scanning electron microscope (SEM), and X-ray diffraction (XRD). Additionally, the electrical and mechanical properties during different stages of aging were examined to reveal the organizational changes and performance variations of Cu–3Ti–2Ni alloy under primary and secondary aging. This study revealed that the alloy exhibited optimal primary aging performance at 450 °C for 4 h, with a strength of 954 MPa and an electrical conductivity of 21.5 %IACS (International Annealed Copper Standard for Conductivity). In comparison to primary aging, both strength and electrical conductivity were effectively improved under secondary aging conditions. The optimum secondary aging process was determined to be aging at 400 °C for 3 h, resulting in a strength of 1133 MPa and an electrical conductivity of 24.2 %IACS. During the aging process, the matrix witnessed the formation of numerous elliptical disc-shaped NiTi and Ni3Ti phases. Notably, the interface of NiTi phases exhibited a stronger coherency effect compared to Ni3Ti. β′-Cu4Ti precipitated uniformly within the matrix during aging, enhancing the alloy's strength. A recovery and recrystallization process occurred during aging, leading to the formation of sub-grains within the matrix.

Selenate reduction mediated by underpotentially deposited Cu on the low index faces of Au in aqueous perchloric acid

Underpotential deposited Cu on the low index faces of single crystal Au electrodes has been found to promote the reduction of selenate, SeO42−(aq),in 0.1 M HClO4 solutions, a behavior analogous to that reported earlier in our laboratory for polycrystalline Au (Strobl et al. J. Electrochem. Soc.2016,163 (13), H1066). Sequential potential step-linear scan voltammetry data collected for Au(111) film electrodes in solutions containing Cu2+(aq) in the μM range afforded evidence that the onset for the electrocatalytic activity occurs for Cu(UPD) coverages, θCu ≈ 0.18, the same value at which complementary microgravimetric data displayed a clear increase in mass. On this basis, a reaction mechanism has been proposed involving the initial reversible formation of an adsorbed adduct, we denote as Cu|SeO42−(ads), followed by a first order irreversible reduction to yield a yet to be identified species, which we denote as Cu|Se(ads), as the rate determining step. Support for this reaction scheme was obtained from numerical solutions of the coupled differential equations that govern the time evolution of Cu|SeO4−(ads) and Cu|Se(ads), yielding best agreement with the experimental data for values of the equilibrium constant for adduct formation and the adduct reduction rate constant of 2.5 × 106 cm3 mol−1, and 9.1 × 10−3 s−1, respectively. This unique electrocatalytic effect has been attributed to a shift in the potential of zero charge of the bare Au substrates induced by Cu(UPD), which promotes the adsorption of HSeO4−(aq) at potentials more negative than those found for the bare substrates, allowing access to overpotentials high enough for its activation and further reduction to ensue.

Correction to: Tracing the Eh–pH evolution of Cu–Pb–As–Zn supergene mineralization using detailed petrography in the Cap Garonne mineral deposit (Provence, France)

Correction to: Tracing the Eh–pH evolution of Cu–Pb–As–Zn supergene mineralization using detailed petrography in the Cap Garonne mineral deposit (Provence, France)

Tracing the Eh–pH evolution of Cu–Pb–As–Zn supergene mineralization using detailed petrography in the Cap Garonne mineral deposit (Provence, France)

Tracing the Eh–pH evolution of Cu–Pb–As–Zn supergene mineralization using detailed petrography in the Cap Garonne mineral deposit (Provence, France)

Synergistic effects of ultrasonic vibration and isothermal treatment on the peritectic transformation and microstructure evolution of Cu–Sn alloy

To facilitate and even complete the peritectic transformation, the ultrasonic vibration (USV) and isothermal treatment were applied to the solidification process of Cu–70Sn alloy. It was found that the peritectic transformation was difficult to carry out due to the limited atomic diffusion under the normal solidification condition. With the single isothermal treatment, the peritectic transformation could be enhanced to some extent, with a small amount of η phase (Cu6Sn5) formed relying on the coarse elongated primary ε phase (Cu3Sn), but the further prolongation of isothermal time led to the abnormally coarsening of microstructure. When the molten alloy was subjected to 1500W USV and 30 min isothermal treatment, the peritectic transformation was dramatically facilitated. The ultrasonic-induced effects of cavitation and acoustic streaming play an important role in the remarkable reduction in the curvature radius of primary ε phase, thereby enhancing the diffusion of Sn solute atoms from the liquid phase to the interior of ε phase at the following isothermal stage. Accordingly, the transformation degree of ε phase to η phase was increased up to 77 %, and there was a high volume fraction of primary ε phase could thoroughly complete the peritectic transformation.

Morphology and valence state evolution of Cu: Unraveling the impact on nitric oxide electroreduction

Ammonia (NH3) serves as a critical component in the fertilizer industry and fume gas denitrification. However, the conventional NH3 production process, namely the Haber-Bosch process, leads to considerable energy consumption and waste gas emissions. To address this, electrocatalytic nitric oxide reduction reaction (NORR) has emerged as a promising strategy to bridge NH3 consumption to NH3 production, harnessing renewable electricity for a sustainable future. Copper (Cu) stands out as a prominent electrocatalyst for NO reduction, given its exceptional NH3 yield and selectivity. However, a crucial aspect that remains insufficiently explored is the effects of morphology and valence states of Cu on the NORR performance. In this investigation, we synthesized CuO nanowires (CuO-NF) and Cu nanocubes (Cu-NF) as cathodes through an in situ growth method. Remarkably, CuO-NF exhibited an impressive NH3 yield of 0.50 ± 0.02 mg cm−2 h−1 at −0.6 V vs. reversible hydrogen electrode (RHE) with faradaic efficiency of 29.68% ± 1.35%, surpassing that of Cu-NF (0.17 ± 0.01 mg cm−2 h−1, 16.18% ± 1.40%). Throughout the electroreduction process, secondary cubes were generated on the CuO-NF surface, preserving their nanosheet cluster morphology, sustained by an abundant supply of subsurface oxygen (s-O) even after an extended duration of 10 h, until s-O depletion ensued. Conversely, Cu-NF exhibited inadequate s-O content, leading to rapid crystal collapse within the same timeframe. The distinctive current–potential relationship, akin to a volcano-type curve, was attributed to distinct NO hydrogenation mechanisms. Further Tafel analysis revealed the exchange current density (i0) and standard heterogeneous rate constant (k0) for CuO-NF, yielding 3.44 × 10−6 A cm−2 and 3.77 × 10−6 cm−2 s−1 when NORR was driven by overpotentials. These findings revealed the potential of CuO-NF for NO reduction and provided insights into the intricate interplay between crystal morphology, valence states, and electrochemical performance.

High-Temperature Crystal Chemistry of Meta-Autunite Group Minerals: Metatorbernite, Cu(UO2)2(PO4)2(H2O)8 and Metazeunerite, Cu(UO2)2(AsO4)2(H2O)8

Thermal expansion of metatorbernite, Cu(UO2)2(PO4)2(H2O)8 (1), and metazeunerite, Cu(UO2)2(AsO4)2(H2O)8 (2), has been investigated using single-crystal and powder X-ray diffraction. Both minerals are prone to dehydration, which proceeds already at ambient conditions. According to the single-crystal XRD data, 1 is stable up to 300(50) K, while 2 is stable up to 250(50) K. Powder XRD studies at various temperatures suggest that 1 dehydrates in three stages at ca. 353, 373, and 483 K, while 2 in two stages at ca. 283 and 543 K. Calculation of the main coefficients of thermal expansion reveals strong anisotropy. The expansion is maximal in the direction normal to the autunite-type layers. This correlates with the anisotropy in thermal evolution of Cu–O bond lengths and differences in the thermal behavior of PO4 and AsO4 tetrahedra.

Microstructure evolution and deformation mechanism with comparison of Ta-2.5 W and Cu under detonation load

The comparison of microstructure evolution of Cu and Ta-2.5 W liner during explosively formed projectile (EFP) formation was studied. The electron backscatter diffraction method (EBSD) was used to statistically characterize the microstructure of the liner before and after deformation. Both recycled EFPs show strong fiber texture and different degrees of recrystallization. The center of the recycled Cu EFP has strong <001> and <111> preferred orientations along the EFP axis, and the density of the texture changes with the deformation strain. Cu EFP has extensive dynamic recrystallization, up to 88%, which is considered to be a traditional dynamic recrystallization mechanism, the temperature is the main controlling factor in the refinement process. On the contrary, the recycled Ta-2.5 W EFP has a strong <101> fiber preferred orientation, and almost no dynamic recrystallization occurs, large strain deformation is the main factor for the microstructure fragment.

Shape memory properties and microstructure evolution of Cu–Al–Fe alloys with different Fe contents

Shape memory properties and microstructure evolution of Cu–Al–Fe alloys with different Fe contents

Microstructural evolution in shear-punch tests: A comparative study of pure Cu and Cu-Cr alloy

Understanding the mechanisms behind microstructural evolution during shear deformation has been a long-standing area of interest. However, establishing a connection between microstructure, mechanical properties, and the extent of shear deformation is challenging and requires refined experimental approaches. Shear-punch testing (SPT) provides a controlled method to introduce shear into small volumes of material that later can be subjected to detailed microstructural characterization. In this study, we utilize an SPT device to induce shear deformation to pure copper (Cu) and a binary copper-chromium (Cu-Cr) alloy. Electron backscatter diffraction and transmission electron microscopy were used to study the mechanisms of plastic deformation after SPT. Our results indicate that shear deformation of pure Cu produces a dense network of intercepting microshear bands upon sustained deformation. Twin boundaries in annealed Cu undergo transformation into high-angle grain boundaries due to simultaneous deviation from the axis-angle pair condition of 60° misorientation on [111] direction. The presence of 50 vol% Cr particles in the soft Cu matrix altered the shear deformation mechanism. Preferential deformation of the Cu matrix in Cu-Cr alloy led to accelerated shear-induced formation of low and high-angle grain boundaries and subsequent grain refinement. Comparatively, insignificant grain refinement occurred in pure Cu samples even at a strain ∼10 times larger (ε = 4.73) than that of the Cu-Cr case (ε = 0.42). This study sheds light on the microstructural evolution of Cu during shear deformation and highlights the significant influence of a hard second phase in modifying the microstructural response mechanisms of a softer matrix.

High temperature deformation behaviour and microstructure evolution in Cu containing High Strength Low Alloy (HSLA) steel

ABSTRACT The hot deformation behaviour of a Cu containing high strength low alloy (HSLA) steel has been evaluated by carrying out hot compression tests over a temperature range of 900 °C to 1100 °C and constant true strain rates of 0.0003 to 1 s−1. Although single peak flow curve is observed predominantly, a tendency to exhibit multiple peaks at low strain rates (0.0003 and/or 0.001 s−1) at temperature greater than 950 °C. The important parameters pertaining to dynamic recrystallisation (DRX), such as critical, peak, steady state stress and strain were ascertained, and the DRX state diagram depicting the variation of critical parameters governing DRX with Zener-Hollomon parameter Z was established. The volume fraction of recrystallised grains, computed from flow stress, as expected, follows a sigmoidal trend indicating higher kinetics at low strain rates for a given temperature. Reconstruction of prior austenite grain boundaries (PAGB) based on electron back scattered diffraction (EBSD) technique for a few select specimens clearly elucidated the effect of temperature and strain rate on the DRX behaviour of the steel. The DRX state diagram established here clearly demarcates the deformation space i.e. temperature-strain rate-stain space into regimes where the material exhibits full DRX, hardening/softening + DRX and only hardening (no DRX) behaviour. This would be useful for designing suitable forging sequence to achieve the desired microstructure and mechanical properties.

Ce Effects on Deformation‐Induced Microstructure Evolution in Cu–Ti–Ni–Mg Alloys

Cu–Ti–Ni–Mg and Cu–Ti–Ni–Mg–Ce alloys are prepared by vacuum induction melting. The hot deformation tests of the two alloys are carried out on the Gleeble‐1500 simulator under the deformation temperatures of 550–950 °C and strain rates of 0.001–10 s−1. The true stress–strain curves of the two alloys are obtained and the constitutive equations are established. The activation energy of the Cu–Ti–Ni–Mg alloy is 344.02 kJ mol−1, and the activation energy of the Cu–Ti–Ni–Mg–Ce alloy is 389.87 kJ mol−1. Based on the processing maps, the optimal processing parameters of the two alloys are obtained. The microstructure of the two alloys is analyzed by electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM). The addition of Ce reduces the dislocation density and texture strength. The CuNi2Ti precipitates are found in both alloys, and there are more precipitates in the Cu–Ti–Ni–Mg–Ce alloys. The addition of Ce increases the flow stress and activation energy, promotes precipitation, and improves the deformation resistance of the alloys.

Pressure tuning of structure, magnetic frustration, and carrier conduction in the Kitaev spin liquid candidate Cu2IrO3

The layered honeycomb lattice iridate Cu$_2$IrO$_3$ is the closest realization of the Kitaev quantum spin liquid, primarily due to the enhanced interlayer separation and nearly ideal honeycomb lattice. We report pressure-induced structural evolution of Cu$_2$IrO$_3$ by powder x-ray diffraction (PXRD) up to $\sim$17 GPa and Raman scattering measurements up to $\sim$25 GPa. A structural phase transition (monoclinic $C2/c \: \rightarrow$ triclinic $P\bar{1}$) is observed with a broad mixed phase pressure range ($\sim$4 to 15 GPa). The triclinic phase consists of heavily distorted honeycomb lattice with Ir-Ir dimer formation and a collapsed interlayer separation. In the stability range of the low-pressure monoclinic phase, structural evolution maintains the Kitaev configuration up to 4 GPa. This is supported by the observed enhanced magnetic frustration in dc susceptibility without emergence of any magnetic ordering and an enhanced dynamic Raman susceptibility. High-pressure resistance measurements up to 25 GPa in the temperature range 1.4--300 K show resilient non-metallic $R$($T$) behaviour with significantly reduced resistivity in the high-pressure phase. The Mott 3D variable-range-hopping conduction with much reduced characteristic energy scale $T_0$ suggests that the high-pressure phase is at the boundary of localized-itinerant crossover. Using first-principles density functional theoretical (DFT) calculations, we find that at ambient pressure $\rm Cu_2IrO_3$ exists in monoclinic $P2_1/c$ phase which is energetically lower than $C2/c$ phase (both the structures are consistent with experimental XRD pattern). DFT reveals structural transition from $P2_1/c$ to $P\bar{1}$ structure at 7 GPa (involving dimerization of Ir-Ir bonds) in agreement with experimentally observed transition pressure.