Addition Of Cu Research Articles

The Effect of Sintering Temperature on the Densification and Magnetic Performance of NiCuZn-Ferrites (CuO: 0-6 wt.%).

This article reported on the effect of Cu-content and sintering temperature on the magnetic permeability and power losses of monolithic iron-deficient NiCuZn-ferrite components with low Cu-contents aimed to be used for power applications at frequencies up to 1 MHz. In particular NiαZnb1-xCuxFe1.9O4 ferrite compositions are investigated with a constant Ni/Zn atomic ratio a/b = 0.9 and 0 < x < 0.017. As found, the addition of Cu enables the achievement of good magnetic performance at lower sintering temperatures and, therefore, lower production cost. At all Cu-contents, the initial permeability as a function of the sintering temperature passes through a maximum above which structural deterioration due to asymmetric grain growth occurs. The temperature at which this maximum permeability occurs depends on the Cu content and coincides with the achievement of the maximum density of 5.1-5.2 g cm-3 (relative density ~97%). At Cu-contents x = 0.006-0.012 and sintering temperatures 1200-1100 °C power losses (tan(δ)/μ at 1 MHz, 25 °C) οf 50 × 10-6 could be achieved and initial permeabilities (10 kHz, 0.1 mT, 25 °C) of around 400 with very good frequency and temperature stability. At CuO content higher than 4 wt.% (i.e., x > 0.012) and sintering temperatures higher than 1150 °C, pronounced microstructural disturbances due to asymmetric grain growth result in low permeabilities and high losses. It is suggested that at low CuO contents and low sintering temperatures, the densification enhancement may not proceed through Cu-rich phase segregation but through the creation of oxygen vacancies.

Can heavy metal pollution stress reduce microbial carbon-use efficiencies?

The fate of soil organic matter (OM) is determined by its microbial use for growth or respiration. Many environmental factors influence microbial OM use, including the presence of contaminants and toxins in the environment, such as heavy metals. We evaluated short- and long-term responses of microbial processes to metal contamination by estimating biomass concentrations and growth rates of bacteria and fungi, respiration, and the resulting microbial carbon-use efficiencies (CUE), and microbial turnover times. We sampled O-horizon from a gradient in boreal forest soils exposed to long-term heavy metal contamination arising from industrial point source since the 1930s to assess long-term effects on soil microorganisms. To estimate microbial responses to short-term metal exposure, additions of Cu were used. Bacterial growth rates and respiration rates decreased in response to long-term metal contamination, while fungal growth rates were unaffected, without changes in CUEs. Bacterial biomass concentrations were independent of soil metal concentrations while fungal and total biomass decreased. Thus, turnover times for bacteria were slowed while fungal turnover times were accelerated by metal pollution. Bacterial growth was inhibited and fungal growth stimulated by experimental Cu additions, with bigger effect sizes in contaminated sites. We interpreted the low rates of growth but high biomass in collected soil samples to indicate that the fungal community included a large mycorrhizal fraction. Although Cu additions decreased the overall microbial OM-use (i.e., the sum of fungal and bacterial growth and total respiration), they also increased the CUE. In conclusion, fungal OM-use was less sensitive than bacterial to metal pollution and the CUE was unaffected. Microbial decomposer communities in contaminated soils were also able to maintain higher CUE when challenged with new metal additions. Our results imply that microbial communities align their trait compositions to environmental challenges, and that this can mitigate the reduction in microbial carbon-use efficiencies that often is expected to occur from environmental stress.

High activity retention Al–Bi–Zn-base composite powder with mild hydrogen generation

Al–10Bi–7Zn and Al–10Bi–7Zn–1.5X (X: Cu, Fe, Ni, in wt.%) composite powders were designed and prepared through phase diagram calculation and gas atomization method. The effects of Cu, Fe, and Ni on the hydrolysis of Al–Bi–Zn-base composite powders for hydrogen production were investigated respectively. The composition and morphology of powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy disperse spectroscopy (EDS) analyses. Hydrolysis performance test results indicate that the additions of Cu, Fe, or Ni can modify the hydrogen production rate and enhance oxidation resistance in Al–10Bi–7Zn ternary alloy composite powder. In the quaternary composite powder system, Al–10Bi–7Zn–1.5Ni (wt.%) exhibits the best performance with the hydrogen generation yield of 75.3% (954.1 mL/g) within 500 min when reacting with distilled water at 60 °C and maintains a hydrogen yield of 57.9% (733.7 mL/g) within 1500 min after being stored (30 °C, relative humidity of 60%) for 7 d. In addition, the mechanism investigation suggested that the additions of Cu, Fe, or Ni in Al–Bi–Zn-base composite powders can stabilize the Al matrix to retain the high activity of powders resulting from inhibiting the cracking of composite powders in the air.

Functional modification of TC4 by Cu-containing titanium dioxide films

To improve the biological fouling and corrosion resistance of Ti6Al4V (TC4) in marine environments, copper-containing titanium dioxide (TiO2(Cu)) films were prepared by magnetron sputtering TiO2(Cu) powder targets. The morphologies of the films showed that they became rough and coarse from 1.6 nm of the TiO2 film to approximately 9 nm of the TiO2(Cu) films, which might be owing to the increase in the deposition rates from 1.33 to 2.08 nm/min. No diffraction orientations of the TiO2 and Cu phases were found compared to those of the TiO2(Cu) powder. Ti, O, and Cu were detected using X-ray photoelectron spectroscopy to confirm the composition of the films. The ratio of Cu2+ increased as the Cu content of the films increased, whereas that of Cu/Cu + scarcely changed. The TiO2 and TiO2(Cu) films exhibited photocatalytic effects and their photocatalytic intensities decreased as the Cu content increased. Hydrophobicity was enhanced by the addition of Cu to the film. The antibiological fouling effect of the TiO2(Cu) films remained unchanged as the Cu/Ti ratio varied. Compared with those of TC4, the corrosion current densities of the TiO2(Cu) films decreased by one order of magnitude and the corrosion potentials increased by 350 mV in artificial seawater, indicating that the corrosion resistance of TiO2(Cu)/TC4 was improved. Importantly, Cu was in abundance in the films for both antibiological and corrosion resistance functions owing to the saturated ratio of Cu/Cu+ irrespective of the Cu/Ti ratio in the films.

The influence of varying Cu doping concentrations on the microstructure, phase evolution and surface wettability of ceramic glazes modified with nano Cu-ZnO

This study intended to develop nano Cu-doped nano ZnO-modified ceramic glazes. In this scope, nano-sized ZnO and nano Cu powders were incorporated into a commercial glaze composition and then the modified glaze was applied to the surface using the spraying method. The glazed tiles were sintered in a laboratory furnace at 1210oC for 10 min. The surfaces of the sintered samples were analyzed using scanning electron microscopy. X-Ray diffractometer, surface profilometer and contact angle goniometer. The study examined the influence of varying levels of Cu doping on the microstructural evolution and formation of phases, surface roughness, as well as the contact angle. Additionally, wettability conversion experiments were conducted under UV light. As a result, the addition of Cu increased the presence of Willemite crystals and also increasing the quantity and size of Plagioclase crystals. The contact angle of the sintered commercial glaze coated surface was measured to be 51.8o. However, when nano ZnO was added, the contact angle reduced to 44.4o. Likewise, the contact angle of the Cu doped nano ZnO coated surfaces decreased even further to approximately 33o. The inclusion of nano ZnO in commercial glaze resulted in a decrease in the Ra value, while doping Cu led to a modest increase in the Ra value. UV irradiation resulted in a reduction in the contact angles of all surfaces.

STUDY ON MAGNETIC PROPERTIES OF FeCoPSiBCu AMORPHOUS ALLOY BY EMPIRICAL ELECTRON THEORY

In this study, a new evaluation method was investigated for the magnetic properties of the amorphous alloys by comparing the experimental results with the theoretical calculations. First, The (Fe[Formula: see text]Co6P[Formula: see text]Si[Formula: see text]B[Formula: see text])[Formula: see text]Cux ([Formula: see text]–0.5) amorphous ribbons were prepared by melt spinning method. Then, the magnetic properties of the prepared amorphous alloys were measured as 165.86–147.04[Formula: see text]emu/g, respectively. On the other side, we analyzed the valence electron structure and obtained the magnetizations as 159.92–158.77[Formula: see text]emu/g by calculating the magnetic moments of unit cells based on empirical electron theory (EET) of solids and molecules. Through comparing the magnetic properties of the calculations with the measurements, we found that the differences between the calculations and the measurements are less than 12% for all samples, meeting the first approximation requirement. Moreover, with the addition of Cu, the change trends both in the calculated and measured magnetic properties are also consistent. These results prove that it is feasible to calculate the magnetic property of the amorphous alloy from the valence electron level using EET, which provides a new method to investigate the soft magnetic property of the amorphous alloy instead of the real measurement.

Construction of polyimide composite aerogels via multi-coordination structure of polymer-metal for improving heat-induced shrinkage, thermal insulation, mechanical and dielectric properties

The fabrication of polyimide (PI) composite aerogels can promote and optimize the characteristics and performance efficiency. But in fact, interface effect and assembly technique are the key problems in preparing PI composite aerogels. To settle this critical issue, a series of PI composite aerogels were designed via forming multi-coordination structure between PI molecular chain and Cu(II) metal ions. Multi-coordination structure connects the two-phase systems closely to obtain the improved comprehensive performances. The resulting PI composite aerogels still have high specific surface and mesoporous structure. The addition of Cu(II) improves the thermal and mechanical properties of the PI composite aerogels with an over 581 °C initial decomposition temperature, tensile strength of up to 9.48 MPa and modulus of up to 232.4 Mpa，along with compression Young’s modulus increased by 173% (up to 28.7 MPa) and stress at 10% strain improved by 150% (up to 1.70 Mpa). In the meantime, the brilliantly controllable dielectric property (with the dielectric constant down to 1.60 and the dielectric loss reaching 0.0171 at 10 MHz) and thermal insulation property (with the thermal conductivity down to 31.9 mWm−1K−1) of PI composite aerogels make them can be used as low dielectric and thermal protection materials. The small heat-induced shrinkage between 100 and 250 °C allows the PI composite aerogels to operate in persistent extreme conditions. Besides, this work can provide a new strategy for preparing PI composite aerogels.

A comparative in vitro and in vivo analysis of the impact of copper substitution on the cytocompatibility, osteogenic, and angiogenic properties of a borosilicate bioactive glass.

The 0106-B1-bioactive glass (BG) composition (in wt %: 37.5 SiO2, 22.6 CaO, 5.9 Na2O, 4.0 P2O5, 12.0 K2O, 5.5 MgO, and 12.5 B2O3) has demonstrated favorable processing properties and promising bone regeneration potential. The present study aimed to evaluate the biological effects of the incorporation of highly pro-angiogenic copper (Cu) in 0106-B1-BG in vitro using human bone marrow-derived mesenchymal stromal cells (BMSCs) as well as its in vivo potential for bone regeneration. CuO was added to 0106-B1-BG in exchange for CaO, resulting in Cu-doped BG compositions containing 1.0, 2.5 and 5.0 wt % CuO (composition in wt %: 37.5 SiO2, 21.6/ 20.1/17.6 CaO, 5.9 Na2O, 4.0 P2O5, 12.0 K2O, 5.5 MgO, 12.5 B2O3, and 1.0/ 2.5/ 5.0 CuO). In vitro, the BGs' impact on the viability, proliferation, and growth patterns of BMSCs was evaluated. Analyses of protein secretion, matrix formation, and gene expression were used for the assessment of the BGs' influence on BMSCs regarding osteogenic differentiation and angiogenic stimulation. The presence of Cu improved cytocompatibility, osteogenic differentiation, and angiogenic response when compared with unmodified 0106-B1-BG in vitro. In vivo, a critical-size femoral defect in rats was filled with scaffolds made from BGs. Bone regeneration was evaluated by micro-computed tomography. Histological analysis was performed to assess bone maturation and angiogenesis. In vivo effects regarding defect closure, presence of osteoclastic cells or vascular structures in the defect were not significantly changed by the addition of Cu compared with undoped 0106-B1-BG scaffolds. Hence, while the in vitro properties of the 0106-B1-BG were significantly improved by the incorporation of Cu, further evaluation of the BG composition is necessary to transfer these effects to an in vivo setting.

Precipitation strengthening and thermal stability in a conventionally non-heat treatable AA3xxx aluminium alloy

We report an unexpected yet significant precipitation-strengthening effect with remarkable thermal stability in an otherwise conventionally non-heat treatable AA3104 aluminium alloy. We reveal that a minor addition of Cu plays a critical role in the alloy's strength and thermal stability, and explain the underpinning mechanisms. The primary strengthening β′ phase can be engineered to exhibit distinctive structural characteristics, including regularly-spaced Cu atom columns at the coherent β′/Al interfaces, stacking faults and resultant domains. Our atomistic simulations rationalise that these microscopic characteristics are directly promoted by the Cu addition. The Cu-decorated interfaces promote β′ phase nucleation and result in strong, directional covalent-like Cu-Si bonding at the β′/Al interfaces. Specifically, the interfacial Cu columns increase the work of separation of the habit-plane interfaces and reduce the interface energy, resulting in significant strengthening and stabilising effects. The Cu columns also facilitate the stacking fault formation in the β′ phase. Collectively, these features enhance the strengthening effect and thermal stability of the precipitates. This study demonstrates the potential for exploring "new" features in "old" alloys to advance alloy science and technology.

Effect of Cu addition on the mechanical properties and corrosion behaviours of Al–9.2Mg–0.8Mn alloy

Microalloying is an effective method to improve the properties of Al–Mg alloys. The microstructure, mechanical properties and corrosion behaviours of Al–9.2Mg–0.8Mn– xCu ( x = 0–1.2 wt-%) alloys are studied to promote the application of Al–Mg alloys. The addition of Cu increases the strength of the alloy, where the ultimate tensile strength of 0.6 wt-% Cu alloy is improved by 43 MPa. Moreover, the addition of Cu significantly affects the corrosion behaviours of alloys. For as-sensitised alloys, compared to the matrix, the 0.1 wt-% Cu alloy shows a 28.3% reduction in pitting corrosion mass loss, which is attributed to the Cu element can form a stable passivation film, and the 0.3 wt-% Cu alloy shows a 15% reduction in intergranular corrosion mass loss, which is attributed to the addition of Cu can restrict the β phase precipitation at grain boundaries. The study shows that Cu-alloying can improve the comprehensive properties of Al–9.2Mg–0.8Mn alloys.

Facile synthesis and grafting of N2O2‐Cu(II) Schiff base complex onto graphene oxide surface: Aspects of its antimicrobial, anticancer, antiCOVID‐19 and photodegradation of methylene blue

AbstractIn this study, a facile synthesis and grafting method is reported for tetradentate Cu(II) Schiff base complex onto the surface of graphene oxide (GO). The Schiff base Cu‐complex was synthesized through the condensation reaction between 2,3‐diamino pyridine and 2‐hydroxy‐1‐naphthaldehyde, followed by the addition of Cu(II) ion to afford N2O2‐Cu(II) complex. The GO was prepared through a modified Hummers’ method and characterized using various spectroscopic and microscopic techniques. The Schiff base Cu‐complex was then grafted onto the surface of GO via a simple solution‐phase reaction, resulting in the formation of N2O2‐Cu(II) Schiff base/GO composite. The fabricated composite was characterized using FTIR spectroscopy, UV–vis, X‐ray diffraction (XRD), and scanning electron microscopy (SEM). Importantly, the prepared N2O2‐Cu(II) Schiff base complex exhibited excellent DNA interaction as well as efficient antimicrobial and anticancer activities. Additionally, it demonstrated potent anticancer activity against hepatocellular carcinoma cells (HepG‐2), and colon cancer cells (HCT‐116) and exhibited promising activity against the COVID‐19 receptor (PDB ID: 6LU7) along with the human DNA receptor (PDB ID: 1BNA). Furthermore, this fabricated heterogeneous catalyst showed enhanced photodegradation of MB with ≈92% conversion and four times recyclability. The overall results suggest that the Cu(II) Schiff base/GO composite has potential applications in various medical and environmental fields, including photodegradation/elimination of harmful organic dyes for water treatment applications.

Microstructure and Phase Transformation Behavior of NiTiCu Shape Memory Alloys Produced Using Twin-Wire Arc Additive Manufacturing

NiTiCu thin walls were produced by twin-wire arc additive manufacturing (T-WAAM) using commercial NiTi and Cu wires as the feedstock materials. This approach aims to solve the problems typically associated with large phase transformation hysteresis in NiTi shape memory alloys. The microstructure, mechanical properties, and phase transformation behavior of the as-deposited NiTiCu alloy were comprehensively examined. The results revealed that the as-deposited NiTiCu alloy was well-formed, with its microstructure showed columnar, equiaxed, and needle-like grains, depending on the location within the deposited walls. The microhardness gradually increased from the first to the third layer. The Cu content was 20.80 at%, and Cu-based precipitates were formed in the as-deposited NiTiCu. The volume fractions and lattice parameters of the matrix and precipitates in the as-deposited NiTiCu material were analyzed using high-energy synchrotron X-ray diffraction. The martensitic phase was identified as a B19 crystal structure, and the as-deposited NiTiCu underwent a one-step B2-B19 phase transformation. The tensile strength and fracture strain were approximately 232 MPa and 3.72%, respectively. In particular, the addition of Cu narrowed the phase transformation hysteresis of the as-deposited NiTiCu alloy from 24.4 to 7.1 ℃ compared with conventional binary NiTi alloys. This study expands the potential of T-WAAM in modifying the phase transformation behavior of NiTi-based ternary alloys.

Sol-Gel-Derived TiO2 and TiO2/Cu Nanoparticles: Synthesis, Characterization, and Antibacterial Efficacy.

This study reports on the antibacterial efficacy of both the TiO2 and TiO2/Cu nanoparticles prepared through the sol-gel method. The materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Brunauer-Emmett-Teller (BET) analysis. The SEM and TEM showed the spherical morphology of the nanoparticles, while EDX and XPS confirmed the incorporation of Cu into the TiO2 nanoparticles. The XRD confirmed the formation of the tetragonal anatase phase of TiO2/Cu while the FTIR revealed the functional groups linked to the doped TiO2 nanoparticles. The thermal stability of TiO2/Cu was found to be lower than pure TiO2. Moreover, TiO2 and the doped TiO2 nanoparticles were notably effective against Bacillus subtilis(B. subtilis) andEscherichia coli(E. coli); however, the addition of Cu to TiO2 did not have any effect on the antibacterial activity probably due to the lower weight content in the composites. Interestingly, the antibacterial efficiency was determined to be 90 and 80% against B. subtilis and E. coli, respectively.

A Paternò-Büchi Reaction of Aromatics with Quinones under Visible Light Irradiation.

Reported herein is a Paternò-Büchi reaction of aromatic double bonds with quinones under visible light irradiation. The reactions of aromatics with quinones exposed to blue LED irradiation yielded oxetanes at -78 °C, which was attributed to both the activation of double bonds in aromatics and the stabilization of oxetanes by thiadiazole, oxadiazole, or selenadiazole groups. The addition of Cu(OTf)2 to the reaction system at room temperature resulted in the formation of diaryl ethers via the copper-catalyzed ring opening of oxetanes in situ. Notably, the substrate scope was extended to general aromatics.

Enhanced the SRB corrosion resistance of 316L stainless steel via adjusting the addition of Cu and Ce elements

316L stainless steel (SS) is the key raw material for the preparation of high-performance oil and gas pipelines, but even 316L with excellent properties will be attacked by sulfate-reducing bacteria (SRB) corrosion. Excellent antibacterial effects have been obtained in other SS systems by doping antibacterial elements. However, the current research on the preparation of antibacterial 316L SS is not comprehensive, and the quantitative analysis of the antibacterial mechanism and doping elements is still unclear. In this paper, the SS with Cu and Ce added were prepared by vacuum induction melting. Then the homogenization treatment combined with hot rolling was used to improve the structure segregation and mechanical properties. Further, the weight loss tests and electrochemical tests were conducted to evaluate the corrosion resistance of SS, the corrosion products and morphology were analysed, and the deformation structure was characterized to clarify the corrosion mechanism of the modified SS and quantify the doping elements. The results indicate that the microstructure after homogenization is mainly austenite, and with the increase of Ce content, the Ce-rich phase segregates. The inhibitory effect of Cu on SRB can be explained by the destructive effect of Cu ions on cell membranes. On this basis, adding a low content of Ce element can increase the permeability of the SRB cell wall and further enhance the attack effect of Cu ions on the cell membrane. The corrosion behavior of alloys shows the deformation structure dependence, with crystal defects and segregation increasing the corrosion rate. The optimal addition amount of Ce is 0.18 wt%, and the strength and elongation of SS are 511.18 MPa and 108.2%, respectively.

Synergistic Enhancement of Strength, Ductility, and Corrosion Resistance of Ti6Al4V Alloy Through Low Cu Doping and Hot Extrusion

A Cu-containing Ti6Al4V alloy is considered an ideal biomedical material due to its excellent antibacterial properties. However, the addition of Cu leads to a mismatch in strength, ductility, and corrosion resistance, which hinders their further application. To address this issue, the study utilized low Cu doping and hot extrusion to optimize the material’s properties. The results showed that the primary lamellar structures were transformed into equiaxed grains, with an average grain size reduced from 10 μm to 300 nm. The nanoequiaxed grains had a homogeneous elemental composition and a stronger base texture, with orientations aligned with the extrusion direction. As a result, synergistic strengthening in terms of strength, ductility, and corrosion resistance was achieved. The film resistance increased from 127 kΩ·cm2 to 325 kΩ·cm2, the ultimate tensile strength (UTS) increased from 1,030 MPa to 1,330 MPa, and the elongation increased from 7% to 21%. These improvements were attributed to the nanostructure and basal texture, which facilitated the formation of a thicker passive film and reduced pitting corrosion, thereby enhancing corrosion resistance. Additionally, the nanoequiaxed grains could provide grain boundary strengthening and texture strengthening on UTS and ensure uniform deformation for elongation.

Effect of 0.5 at. % Cu addition on the crystallization behavior and soft magnetic properties of Fe83B11C1Si2P3 alloy

In order to gain insight into how the addition of Cu element affects the crystallization mechanism of amorphous nanocrystalline alloys and soft magnetic properties, the crystallization behavior of (Fe0.83B0.11Si0.02P0.03C0.01)100-xCux (x = 0 and 0.5) amorphous ribbons was investigated based on kinetic and thermodynamic behavior under non-isothermal and isothermal annealing conditions. The results show that under non-isothermal annealing conditions, the Cu0.5 amorphous ribbon not only favors the formation of the amorphous structure, but also enlarges the temperature window for annealing and improves the thermal stability of the α-Fe(Si) phase. At the same time, the Cu0.5 amorphous ribbon shows slow kinetic and is insensitive to heating rate change during annealing treatment. Under isothermal conditions, the addition of Cu decreases the nucleation activation energy (En) and increases the growth activation energy (Eg). This further indicates that the nucleation of α-Fe(Si) grains is easier than the growth process, which is conducive to the formation of a homogeneous nanostructure and improves the soft magnetic properties of the alloy. Compared to Cu0 amorphous ribbon, it is also shown that the Cu0.5 amorphous ribbon changes the crystallization mechanism from diffusion-controlled one-dimensional to two-dimensional growth when the crystallization volume fraction x is 10–30 vol%. While three-dimensional growth become dominated when x is reaches 60 vol% for both ribbons. Therefore, the kinetics of crystallization as well as microstructure supports that the Cu0.5 ribbon is able to exhibit uniformly fine nanocrystalline structures. Further, the Cu0.5 nanocrystalline ribbon shows a higher Bs of 1.85 T and a lower Hc of 2.55 A/m, respectively, and the favorable (100) orientation of α-Fe(Si) grains formed after annealing is another factor to increase Bs.

Effect of Copper Content on the Microstructure and Properties of the Sintered Porous Aluminum Wick

Porous aluminum has been widely used as a wick, an electrode, and in other products, due to its advantages of a light weight, pore uniformity, and corrosion resistance. However, the dense alumina layer on the surface of Al powder hinders its densification during sintering. In this paper, porous aluminum was prepared via loose powder sintering with the addition of Cu as a sintering aid. The effects of Cu content on the microstructure and wick properties of the porous aluminum were investigated. The results showed that, with increasing Cu content, the porosity and capillary properties of porous Al decreased, while the compressive strength improved. The optimal Cu content was determined to be 3 wt.% and the prepared porous Al has a porosity of 47.5%, plateau stress of 11.82 MPa, and capillary characteristic parameter of 6.72 × 10−8 N, meeting the requirements for wicks in heat pipes. These findings contribute to the demand for the lightweight design of heat pipes for aerospace applications.

Numerical Simulation and Sensitivity Analysis Using RSM on Natural Convective Heat Exchanger Containing Hybrid Nanofluids

This work presents a numerical analysis for exploring heat transfer phenomena in an enclosed cavity using magnetohydrodynamics natural convection. Because of the numerous real-world applications of nanofluids and hybrid nanofluids in industrial and thermal engineering developments, hybrid nanofluids are used as fluid mediums in the fluid field. A hexagonal-shaped heat exchanger is taken with two circular surfaces along the middle part. The upright circular surface acts as a homogeneous heat source, while the lower circular surface functions as a heat sink. The remaining portions of the adjacent walls are thermally insulated. The copper (Cu) and titanium dioxide (TiO2) nanoparticles are suspended into water to make a hybrid nanofluid. For solving the corresponding governing equations, the weighted-residual finite element method is applied. To explain the major outcomes, isotherms, streamlines, and many others 2D and 3D contour plots are involved graphically with a physical explanation for different magnitudes of significant parameters: Rayleigh number 103≤Ra≤106, Hartmann number 0≤Ha≤100, and nanoparticle volume fraction 0≤ϕ≤0.06. The novelty of this work is to apply response surface methodology on the natural convective hybrid nanofluid model, to visualize 2D and 3D effects, and to study the sensitivity of independent parameters on response function. Due to the outstanding thermal properties of the hybrid nanofluid, the addition of Cu and TiO2 nanoparticles into H2O develops the heat transfer rate to 35.85% rather than base fluid. Moreover, a larger magnitude of Ra and the accumulation of mixture nanoparticles result in the thermal actuation of a hybrid nanofluid. With greater magnetic impact, an opposite response is exhibited.

Effect of Alloying Elements on the Microstructure and Magnetic Properties of Mechanically Alloyed AlNiCo‐Based High‐Entropy Alloys

Herein, the effect of addition of Cu, Fe, and CuFe on microstructure and magnetic properties of equiatomic ternary AlNiCo alloy is reported. This addition of Cu, Fe, and CuFe to AlNiCo results in L12, B2, and mixed α + B2 phases, respectively, during the mechanical alloying (MA) and subsequent annealing process. The low‐temperature magnetic properties show that the addition of nonmagnetic Cu to AlNiCo enhances the coercivity, while Fe enhances the saturation magnetization value. Further from the study of magnetic properties, it is suggested that the phase segregation effects are minimum in MA process compared to melt process. It is also shown that the disorder plays a significant role in controlling the magnetic properties. The observed anomalous magnetic behavior is discussed in terms of modifications in exchange interactions between constituent elements due to chemical and structural disorder.