Cu-Ni Alloys Research Articles

Laser powder bed fusion of a Cu-Ni-Al alloy using the compositional grading approach

Using a modified laser powder bed fusion (LPBF) technique, a compositionally graded Cu-Ni alloy was fabricated. Through microstructural and mechanical characterization on the samples extracted from it, the addition of 7.6 wt.% Ni to Cu is identified as the minimum required for obtaining a crack-free and nearly-fully-dense coupons using LPBF. Subsequently, 3 wt.% Al was added to the Cu-7.6 wt.% alloy to deplete the solute Ni atoms from the matrix through the precipitation of Ni3Al upon aging of the LPBF Cu-Ni-Al alloy, which simultaneously enhances the strength and electrical conductance of the alloy. Through this example, we demonstrate the potential of high-throughput screening of alloys suitable for LPBF through the fabrication of the compositionally graded alloys and subsequent alloy design for optimum property combinations.

Preparation of porous Cu‐rich CuNi electrodes via electrochemically dealloying in ionic liquid

Commercial CuNi (55/45 wt%) alloy can be electrochemically dealloyed to be the porous Cu-rich CuNi electrodes, which reveals an enhanced catalytic activity toward nitrate reduction in contrast with that of the mother alloy electrodes. In comparison with the use of aqueous electrolytes, the formation of the porous structures is reproducible if ionic liquid (IL) is used as the electrolyte for the dealloying process. During the dealloying process, a relatively more quantity of Ni but both Ni and Cu were electrochemically oxidized to be Ni(II) and Cu(II) complex ions; different ions seemed to own different coordinating molecules in accordance with the NMR analysis. Cu(II) ions could be reduced to Cu metal and deposited upon the counter electrode during the dealloying process. Ni(II) ions, on the other hand, can be mostly removed from the IL phase by extraction into the immiscible water phase. A sustainable system may be developed for the preparation of nitrate-active electrodes in accordance with the study shown here.

Using Molecular Dynamic Simulation to Understand the Deformation Mechanism in Cu, Ni, and Equimolar Cu-Ni Polycrystalline Alloys

The grain boundaries and dislocations play an important role in understanding the deformation behavior in polycrystalline materials. In this paper, the deformation mechanism of Cu, Ni, and equimolar Cu-Ni alloy was investigated using molecular dynamic simulation. The interaction between dislocations and grain boundary motion during the deformation was monitored using the dislocation extraction algorithm. Moreover, the effect of stacking fault formation and atomic band structure on the deformation behavior was discussed. Results indicate that dislocations nucleate around the grain boundary in copper, the deformation in nickel changes from planar slip bands to wavy bands, and high density of dislocation accumulation as well as numerous kink and jog formations were observed for the equimolar Cu-Ni alloy. The highest density of the Shockley dislocation and stacking faults was formed in the equimolar Cu-Ni alloy which results in the appearance of a huge gliding stage in the stress–strain curve. The grain boundaries act as a sinking source for vacancy annihilation in Ni and Cu; however, this effect was not observed in an equimolar Cu-Ni alloy. Finally, radial distribution function was used to evaluate atom segregation in grain boundaries.

Enhanced Cyclopentanone Yield from Furfural Hydrogenation: Promotional Effect of Surface Silanols on Ni-Cu/m-Silica Catalyst

A direct alkaline hydrothermal method was used to synthesize mono- and bimetallic Ni and Cu on mesoporous silica (m-SiO2) as catalysts for the hydrogenation of furfural (FAL) to cyclopentanone (CPO). The catalysts were characterized by XRD, FTIR, H2-TPR, SEM, TEM, HR-TEM, XPS, ICP, BET, and CHN analysis. The results demonstrate that the addition of Cu metal improved the reducibility of Ni catalysts and revealed Ni-Cu alloy formation over m-SiO2. Furthermore, XPS and FTIR results reveal that the silanol groups on the catalyst surface play an important role in the ring rearrangement of furfuryl alcohol. Hence, the effect of silanol groups in the FOL rearrangement was studied in detail. Among the catalysts at fixed metal loading of 20 wt.%, Ni5Cu15/m-SiO2 catalyzed the formation of CPO as the main product due to the synergy of Ni-Cu alloy and surface silanol groups. Ni5Cu15 supported on a commercial mesoporous silica (Ni5Cu15/C-SiO2) showed inferior performance compared with the Ni5Cu15/m-SiO2 catalyst for the FAL hydrogenation. Reaction temperature and time were also optimized for the enhanced CPO yield over Ni5Cu15/m-SiO2. The Ni5Cu15/m-SiO2 catalyst is durable, as demonstrated by stability tests over multiple reuses. This effective and flexible NixCuy on m-SiO2 catalyst provides an effective candidate for efficient upgrading of furanics in selective hydrogenation reactions.

Morphology Engineering in Multicomponent Hollow Metal Chalcogenide Nanoparticles.

Hollow metal chalcogenide nanoparticles are widely applicable in environmental and energy-related processes. Herein, we synthesized such particles with large compositional and morphological diversity by combining scanning probe block copolymer lithography with a Kirkendall effect-based sulfidation process. We explored the influence of temperature-dependent diffusion kinetics, elemental composition and miscibility, and phase boundaries on the resulting particle morphologies. Specifically, CoNi alloys form single-shell sulfides for the synthetic conditions explored because Co and Ni exhibit similar diffusion rates, while CuNi alloys form sulfides with various types of morphologies (yolk-shell, double-shell, and single-shell) because Cu and Ni have different diffusion rates. In contrast, Co-Cu heterodimers form hollow heterostructured sulfides with varying void numbers and locations depending on synthesis temperature and phase boundary. At higher temperatures, the increased miscibility of CoS2 and CuS makes it energetically favorable for the heterostructure to adopt a single alloy shell morphology, which is rationalized using density functional theory-based calculations.

Investigation on hybrid bonding of tungsten/steel with in-situ formed composites interlayer

Hybrid bonding between steel and W using 88(97W-2.7Cu-0.3Ni)−12Ni powder mixtures sandwiched between Ni and Cu foils was carried out in vacuum for 60 min at 1120 ℃ with a pressure of 5 MPa. The assembly sequence of bonding specimens was steel/Ni/Cu/88(97W-2.7Cu-0.3Ni)−12Ni powder mixtures/Cu/Ni/Cu/W. The microstructures and composition distribution of the joint were studied by SEM and EDS. Joint properties were evaluated by shear experiment tests, and the fracture characteristics of the shear samples for the joints were also determined by SEM. The results showed that the joints comprised steel/Ni/composites/Cu-Ni/W, wherein the composites interlayer consisting of tungsten heavy alloy and irregular Ni agglomerate in-situ formed by the combined sintering of 88(97W-2.7Cu-0.3Ni)−12Ni powder mixtures. The hybrid bonding mechanisms of the interfaces in the joint include solid-phase diffusion bonding and transient liquid phase diffusion bonding. An additional hot-dip experiment found that obvious solid-liquid interface diffusion and Ni segregation occurred under the bonding conditions, and a large number of W atoms diffused into the Cu-Ni liquid phase. In the Cu-Ni alloy layer, the content of element W is more than 4.22% (at.%). The average shear strength of W/steel joints was 263 ± 7 MPa and all the shear samples were fractured in the W near the bonding interface.

Microstructure and Properties of Nickel-Based Gradient Coatings Prepared Using Cold Spraying Combined with Laser Cladding Methods

A cold spray-laser cladding composite gradient coating (CLGC) was successfully formed on a Cu substrate. In comparison with traditional laser cladding gradient coatings (LGC), cold spraying the pre-set Ni-Cu alloy's intermediate transition layer not only mitigates the negative impacts due to the high reflectivity of the copper substrate but also helps to minimize the difference in the coefficients of thermal expansion (CTE) between the substrate and coating. This reduces the overall crack sensitivity and improves the cladding quality of the coating. Besides this, the uniform distribution of hard phases in CLGC, such as Ni11Si12 and Mo5Si3, greatly increases its microhardness compared to the Cu substrate, thus resulting in the value of 478.8 HV0.5 being approximately 8 times that of the Cu substrate. The friction coefficient of CLGC is lowered compared to both the Cu substrate and LGC with respective values of 0.28, 0.54, and 0.43, and its wear rate is only one-third of the Cu substrate's. These results suggest CLGC has excellent anti-wear properties. In addition, the wear mechanism was determined from the microscopic morphology and element distribution and was found to be oxidative and abrasive. This approach combines cold spraying and laser cladding to form a nickel-based gradient coating on a Cu substrate without cracks, holes, or other faults, thus improving the wear resistance of the Cu substrate and improving its usability.

Enhanced catalytic performance of CuNi bimetallic nanoparticles for hydrogen evolution from ammonia borane hydrolysis

Ammonia borane (AB, NH3BH3) hydrolysis is an effective way to safely generate hydrogen. However, a suitable catalyst is indispensable because the hydrolytic reaction cannot take place kinetically at room temperature. In this work, CuNi alloy nanoparticles are immobilized on porous graphitic carbon nitride (g-C3N4) with a facile adsorption-chemical reduction method. Benefiting from the hierarchical porous structure of the support, the interesting alloy effect of Cu and Ni, as well as the synergistic effect between g-C3N4 and the CuNi alloys, the optimal Cu0·7Ni0.3/g-C3N4 catalyst displays excellent catalytic performance in AB hydrolysis, such as high turnover frequency (2.08 min−1, at 303 K), low apparent activation energy (23.58 kJ mol−1), and satisfactory durability. The results verify that the optimal catalyst has particular potential in hydrogen energy utilization due to the advantages such as the facile preparation procedure, low cost and excellent catalytic behavior.

Tuning CO2 Hydrogenation Selectivity through Reaction-Driven Restructuring on Cu-Ni Bimetal Catalysts.

Tuning the selectivity of CO2 hydrogenation is of significant scientific interest, especially using nickel-based catalysts. Fundamental insights into CO2 hydrogenation on Ni-based catalysts demonstrate that CO is a primary intermediate, and product selectivity is strongly dependent on the oxidation state of Ni. Therefore, modifying the electronic structure of the nickel surface is a compelling strategy for tuning product selectivity. Herein, we synthesized well dispersed Cu-Ni bimetallic nanoparticles (NPs) using a simple hydrothermal method for CO selective CO2 hydrogenation. A detailed study on the monometallic (Ni and Cu) and bimetallic (CuxNi1-x) catalysts supported on γ-Al2O3 was performed to increase CO selectivity while maintaining the high reaction rate. The Cu0.5Ni0.5/γ-Al2O3 catalyst shows a high CO2 conversion and more CO product selectivity than its monometallic counterparts. The surface electronic and geometric structure of Cu0.5Ni0.5 bimetallic NPs was studied using ambient pressure X-ray photoelectron spectroscopy (AP-XPS) and in situ diffuse reflectance infrared Fourier-transform spectroscopy under reaction conditions. The Cu core atoms migrate toward the surface, resulting in the restructuring of the Cu@Ni core-shell structure to a Cu-Ni alloy during the reaction and functioning as the active site by enhancing CO desorption. A systematic correlation is obtained between catalytic activity from a continuous fixed-bed flow reactor and the surface electronic structural details derived from AP-XPS results, establishing the structure-activity relationship. This investigation contributes to providing a strategy for controlling CO2 hydrogenation selectivity by modifying the surface structure of bimetallic NP catalysts.

Finite element simulation of electric discharge machining process during machining of NiTi, NiCu and BeCu alloys

Advanced alloys, in addition to high strength, nonmagnetic qualities, high fatigue strength, corrosion resistance and non-sparking properties, also exhibit good wear resistance, corrosion resistance and good fatigue strength. As a result, conventional machining presents machining issues. However, electrical discharge machining provides a practical solution. With experimental validation, the current study is concerned with developing an electrical discharge machining model. In this study a single discharge finite element model was developed and simulated a three-dimensional axis symmetrical model using analysis software. The material removal rate was calculated using the temperature profile. A validation experiment was carried out to verify the numerical results. In the comparison of numerical and experimental results, an average error of 6.189 % was obtained. This shows that the finite element model results are in good agreement with experimental results. Further finite element can mimic the experimental conditions accurately and predict the material removal rate.

Visible light-regulated thermal catalytic selectivity induced by nonthermal effects over CuNi/CeO2

Solar-assisted photothermal catalysis is a fascinated picture of chemical and energy conversion. However, it is difficult to distinguish the nonthermal effects due to the thermal and nonthermal tend to exhibit similar experimental results. Here, we reported that the CuNi alloy deposited CeO2 (CuNi/CeO2) with visible light excited carriers at the interface can promote CO2 reduction in the photothermal catalysis. Impressively, the CuNi/CeO2 exhibit different product selectivities in the dark and visible light reactions, especially the light promoted the further hydrogenation to CH4 conversion. Detailed experiments reveal that the hot electron transfer between plasmon metal Cu and metal Ni under visible light excitation alters the pathway of thermal reduction while increasing surface hydroxyl and oxygen vacancies as CO2 trapping sites. The excessive H2 activation under visible irradiation induces the deep reduction of CO2 to CH4, instead of reverse water gas shift. Combining with in-situ DRIFTS, quasi-situ EPR, H2 pulse and DFT calculations, the nonthermal effects of CO2 reduction is proposed over CuNi/CeO2 with electrons transfer between Cu and Ni nanoparticles.

CuNi Alloy NPs Anchored on Electrospun PVDF-HFP NFs Catalyst for H2 Production from Sodium Borohydride.

Non-noble CuxNi1-x (x = 0, 0.1, 0,2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1) alloy nanoparticles supported on poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) nanofibers (NFs) are successfully fabricated. The fabrication process is executed through an electrospinning technique and in situ reduction in Cu2+ and Ni2+ salts. The as-synthesized catalysts are characterized using standard physiochemical techniques. They demonstrate the formation of bimetallic NiCu alloy supported on PVDF-HFP. The introduced bimetals show better catalytic activity for sodium borohydride (SBH) hydrolysis to produce H2, as compared to monometallic counterparts. The Cu0.7 Ni0.3/PVDF-HFP catalyst possesses the best catalytic performance in SBH hydrolysis as compared to the others bimetallic formulations. The kinetics studies indicate that the reaction is zero order and first order with respect to SBH concentration and catalyst amount, respectively. Furthermore, low activation energy (Ea = 27.81 kJ/mol) for the hydrolysis process of SBH solution is obtained. The excellent catalytic activity is regarded as the synergistic effects between Ni and Cu resulting from geometric effects over electronic effects and uniform distribution of bimetallic NPs. Furthermore, the catalyst displays a satisfying stability for five cycles for SBH hydrolysis. The activity has retained 93% from the initial activity. The introduced catalyst has broad prospects for commercial applications because of easy fabrication and lability.

Corrosion and bacterial growth mitigation in the desalination plant by imidazolium based ionic liquid: Experimental, surface and molecular docking analysis

The desalination plants wieldy used CuNi alloys. However, it faces a fundamental corrosion problem in a 3.5% NaCl solution containing sulfide ions. In this research, we have examined ionic liquid's corrosion and bacterial inhibition activity, i.e., 1-Dodecyl-3-methylimidazolium iodide (IMD-IL). The obtained data from weight loss and electrochemical reveals the corrosion inhibitive performance of IMD-IL is 96.8% at 100 mg/L. The EIS suggests increasing the charge transfer resistance and film resistance with increasing IMD-IL amount, supporting the inhibitive action of IMD-IL molecules. The biological activity results reveal the deactivation of SRB action after the addition of IMD-IL molecules. The SEM and EDX studies support the IMD-IL adsorption onto the CuNi surface. The molecular docking results confirmed that IMD-IL could bind the cytochrome c, inhibiting its activity and thereby interrupting the electron transport pathway between bacteria and the CuNi.

Investigation of nano-tribological behaviors and deformation mechanisms of Cu-Ni alloy by molecular dynamics simulation

With the rapid development of micro/nanodevices, it is critical to investigate and disclose the nano-sized tribological properties and deformation mechanisms. This paper aimed to understand nano-tribological behaviours and deformation process of Cu-Ni alloy. The effects of the pressed depth, alloy composition, and sliding distance on friction state, dislocation density, and von-Mises strain stress (VMSS) are comprehensively investigated using molecular dynamics simulation. The results indicate that a larger pressed depth brings about more lattice defects in the pressed region and a higher transverse force, the stacking fault and dislocation density increased rapidly as the Cu content increases, and a longer sliding distance results in more plastic deformation and the number of wear atoms generated. As the pressed depth and sliding distance rise, the plastic deformation and sub-surface damage are aggravated, however, Cu atoms improve the Cu-Ni alloy resistance of deformation. This work can enrich the understanding on the nano-tribological behaviour and deformation mechanism of Cu-Ni alloy during the ultraprecision process.

Пластическое течение в твердых растворах Cu-Ni как автоволновой процесс

The influence of Ni content in Cu-Ni alloys on the localization of plastic flow under uniaxial tension has been studied. The regularities of localization of plastic deformation during linear and parabolic deformation hardening, as well as at the yield point, depending on the Ni content in the solid solution, have been studied by the speckle photography method. The influence of the Ni content on the duration of the stages of parabolic deformation hardening in alloys of different composition was found. The dependence of the spatial period of localization of plastic deformation (the length of the localization autowave) on the Ni content in the studied alloys is established. Keywords: localization of plastic deformation, autowaves, copper-nickel alloys, structure, mechanical properties, deformation and impurity hardening.

Effect of Ni atomic fraction on active species of graphene growth on Cu-Ni alloy catalysts: a density functional theory study.

Cu-Ni alloys are promising catalysts for precisely controlling the number of graphene layers grown by chemical vapor deposition (CVD). However, the theoretical understanding of the effect of the Ni atomic fraction on the active species, which helps determine the mechanism of graphene growth, is still limited. Here, we examine the energetics, electronic properties, and populations of potential carbon source species (CH3, CH2, CH, C) on Cu-Ni alloy catalysts with various Ni atomic fractions under various CVD growth conditions using density functional theory combined with atomistic thermodynamics. An increased Ni atomic fraction of the Cu-Ni alloy catalyst increases the d-band center and d-orbital delocalization of the Ni atoms. Therefore, the stability of the carbon source adsorbed on the surface and subsurface of the catalyst increases. Relative population analysis shows that the CH and C monomers on the surface are the active species that drive surface-mediated growth on Cu-Ni catalysts with low Ni atomic fractions. The dominance of CH and C species can be further tuned by adjusting the growth temperature and partial pressure of H2. In contrast, in a Cu-Ni catalyst with a high Ni atomic fraction, the C monomer species on the subsurface has high stability and acts as an active species that controls the cooling-induced segregation growth mechanism. This study provides an essential insight into the atomistic mechanism of graphene growth in Cu-Ni alloy catalysts.

Laser-controlled tandem catalytic sites of CuNi alloys with ampere-level electrocatalytic nitrate-to-ammonia reduction activities for Zn–nitrate batteries

Laser-constructed CuNi alloy electrodes with tandem sites of Ni provide H* and Cu for NO3−reduction, achieving ampere-level NO3−reduction and high-performance Zn–NO3−batteries.

Plastic flow in Cu-Ni solid solutions as an autowave process

The influence of Ni content in Cu-Ni alloys on the localization of plastic flow under uniaxial tension has been studied. The regularities of localization of plastic deformation during linear and parabolic deformation hardening, as well as at the yield point, depending on the Ni content in the solid solution, have been studied by the speckle photography method. The influence of the Ni content on the duration of the stages of parabolic deformation hardening in alloys of different composition was found. The dependence of the spatial period of localization of plastic deformation (the length of the localization autowave) on the Ni content in the studied alloys is established. Keywords: localization of plastic deformation, autowaves, copper-nickel alloys, structure, mechanical properties, deformation and impurity hardening.

Cu–Ni alloy decorating N-doped carbon nanosheets toward high-performance electrocatalysis of mildly acidic CO2 reduction

The nitrogen-doped “willow leaf” shaped carbon nanosheets modified with Cu-Ni alloy shows excellent electrocatalytic activity for reducing CO2 to CO under mildly acidic media.

First-principles study of binary austenitic Ni-Cu alloys

The backbone of the Monel alloys is built on the Ni-Cu system. As a result of their inherent properties such as high strength, toughness and excellent corrosion resistance, these alloys are widely used in marine, chemical and oil industries. A major setback of Ni-Cu alloys in application is the unsatisfactory wear performance. One way to get a grip around this issue is by understanding their fundamental properties. Thus, in order to lay a foundation for future materials development, this study employs first-principles approach to predict structural and mechanical properties of binary Ni-Cu austenitic alloys.