Addition Of Cu Research Articles

Influence of Cu addition on the microstructure and tribological properties of Ti-based laser cladded composite coatings on TC4

Ti-based composite coatings using TC4/Ni60/Cu mixed powders with of 0, 5, and 10 wt% Cu additions were prepared on TC4 by coaxial powder feeding laser cladding to investigate the effects of the addition of Cu on their microstructure and tribological properties. Multiple technical methods were performed for characterization, and the results revealed that TiC, TiB, Ti2Ni, and α-Ti precipitated in all coatings. As Cu added, the coating microstructure was gradually refined, and quasi-nanometer Ti3Cu was synthesized in the 5 and 10 wt%-Cu coatings where the Ti3Cu-Ti2Ni and Ti3Cu-α-Ti composite structure phase were formed. The microhardness and wear resistance of the three coatings were higher than that of the TC4 substrate and presented a gradual decrease with the Cu additions. The friction coefficients of the above coatings were higher than those of TC4 and generally consistent. The study found that the appropriate Cu addition could enhance the forming quality of the coating, effectively refine the microstructure, improve the uniformity of the microstructure distribution, and reduce fluctuations in microhardness and tribological properties.

Impact of Crystallite Size and Phase Boundaries on Magnetic and Thermoelectric Properties of Cu-Added BiFeO3.

In this study, bismuth ferrite (BFO) and copper-added BFO were synthesized using the coprecipitation method. The incorporation of copper into the BFO lattice led to a reduction in the phase percentage of BFO due to the early formation of CuBi2O4. X-ray diffraction analysis revealed a decrease in crystallite size up to 0.1 CBFO, followed by an increase. This reduction in crystallite size causes an imbalance between the spins of the sublattices, resulting in an antiferromagnetic core/ferromagnetic shell (AC/FS) structure. The uncompensated spins generated by the decreasing crystallite size weaken the ferromagnetic properties with the addition of Cu. Additionally, the reduction in crystallite size leads to decreased electrical conductivity due to carrier scattering, with the maximum conductivity observed in BFO attributed to its volatilization. The Seebeck coefficient enhancement in 0.1 and 0.15 CBFO indicates an energy filtering effect caused by barriers at the phase boundaries. The introduction of Cu into the BFO matrix also results in reduced lattice thermal conductivity due to active centers for phonon scattering created by Cu-induced defects. The lowest lattice thermal conductivity was observed in 0.1 CBFO, which is attributed to the significant reduction in crystallite size and the presence of phase boundaries enhancing phonon scattering. The highest thermoelectric figure of merit (zT) was achieved in thermally unstable BFO due to Bi3+ volatilization, which was mitigated by the formation of CuBi2O4 in CBFO.

Theoretical prediction of high temperature mechanical, thermodynamic and surface O adsorption properties of W-Cu alloys: Advanced high temperature super strength alloy materials

This paper constructs four alloy structural models of W15Cu1, W14Cu2, W13Cu3 and W12Cu4 as research objects. Based on phonon spectra analysis, the structure of W12Cu4 is unstable. Thus, the mechanical and thermodynamic properties for pure W, W15Cu1, W14Cu2 and W13Cu3 are studied using first-principles methods. The results show that the bulk modulus of W-Cu alloys exhibits the characteristics of high-temperature strength alloys. In particular, the bulk modulus of W14Cu2 and W13Cu3 increases rapidly with temperature increasing; Meanwhile, The W-Cu alloys at high temperatures exhibit low expansion behavior. The coefficient of thermal expansion of W14Cu2 at 1290 K starts to be lower than that ofW, and decreases with temperature increasing. At 1370 K, the coefficient of thermal expansion of W13Cu3 begins to be lower than that of W14Cu2, which also decreases with temperature increasing. The W-Cu alloys at high temperatures exhibit excellent phonon thermal conductivity. The phonon thermal conductivity of W14Cu2 at 2230 K transcends pure W and then maintains a thermal conductivity of about 5.55Wm-1K−1. The phonon thermal conductivity of W13Cu3 at 2140 K begins to transcend W14Cu2, and also exceeds pure W at 2180 K, and increases rapidly with temperature increasing. At 0 K, the addition of Cu to W reduces the mechanical strength but increases the ductility.

Unraveling the potential of Cu addition and cluster hardening in Al-Mg-Si alloys

With the aim of further exploiting the trade-off between formability and strength in Al alloys, this study addresses the influence of Cu in Al-Mg-Si alloys that achieve simultaneously high strength and high ductility via cluster hardening. The study carefully examines the mechanical properties and strain hardening behavior of various Mg/Si ratios with and without Cu and compares the effects of pre-aging and atypical long-term low-temperature aging treatments at 100°C to conventional heat treatments. Interestingly, in all cases adding Cu improved ductility. In the extremal case cluster hardening plus the addition of Cu quadruples elongation, while keeping yield strength similar to the classical T6 state. The results of the study are discussed with a focus on the dense distribution of clusters and partial hardening phases based on atom probe tomography data. Most importantly, the cluster-hardened alloys exhibit pronounced strain-hardening properties, which we evaluate using a Kocks-Mecking approach in combination with a microstructural analysis in the pre-aging and long-term aging condition. The key finding of the study involves the role of Cu in refining clusters/precipitates, where it causes a substantial increase in number density and volume fraction. This refinement, in combination with strain-induced clustering, contributes significantly to improving the alloys’ overall mechanical performance and underlines the central role of Cu in tailoring microstructural features, especially in alloys primarily strengthened by clusters.

Tuning the CO2 hydrogenation activity and selectivity of TiO2 nanorods supported Rh catalyst via secondary‐metals addition

AbstractSecondary‐metals promotion is key to tune the CO2 hydrogenation performance of Rh‐based catalyst. We describe the addition of Cu or Co in TiO2 nanorods supported Rh catalyst (viz., RhMx/TiO2), showing significant impact on the CO2 hydrogenation activity and productivity. Cu addition can promote the partial hydrogenation to alcohols (methanol and ethanol), whereas Co led to the deep hydrogenation to alkanes (CH4, C2H6). Comparative time‐resolved in situ DRIFTS studies with H2/D2 isotopic exchange further reveal that both surface adsorbed CO* and formates could be the key reaction intermediates during the CO2 hydrogenation over RhMx/TiO2 (especially the RhCu2.5/TiO2), in which the interaction strength of CO* regulated by secondary‐metals addition was key to tune the reaction pathways and productivity. The findings suggested that rational design of active metal sites, for example the synergy between Rh and secondary‐metals, is highly needed to promote the CO insertion and CC coupling to produce ethanol.

Bulk graphene-based composites with artificial nacre-like laminated structure: Microstructure and mechanical properties

In this study, the bulk Cu/reduced graphene oxide (Cu/rGO) composites featuring an artificial nacre-like laminated structure were successfully fabricated using spark plasma sintering (SPS), and the microstructure and mechanical properties of the resulting composites were investigated. The Cu/rGO composites demonstrated a distinct laminated structure, and their relative densities increase with Cu addition. Moreover, the presence of trace amounts of in-situ interfacial reaction products (CuO and CuO2,) were observed to enhance the adhesive strength at the Cu-rGO interface. Mechanical testing of the composites showed notable improvements in both compressive strength and ductility compared to a bulk monolithic rGO sample. Specifically, the bulk rGO composites with a 35.05 wt% addition of Cu displayed an enhancement of ∼67 % in compressive strength and ∼19 % in ductility relative to the pure rGO sample. These improvements are attributed to synergetic strengthening and toughening mechanisms within the rGO composites. The enhanced strength and ductility of the Cu/rGO composites significantly boost their wear resistance. This research not only demonstrates the effectiveness of incorporating Cu into rGO matrices but also suggests a promising avenue for the development of novel bulk rGO composites with engineered laminated structures.

Tribological and electrochemical behaviour study of porous TiNiCu alloys manufactured by the powder metallurgy process

ABSTRACT The experimental work aims to study the effect of the Copper (Cu) addition on the tribological and electrochemical behaviour of porous Ti50Ni50-x-Cux alloys. In the first step pure metal powders of titanium (Ti), nickel (Ni), and Cu were ball-milled during 8 h in a planetary ball mill, and then compacted under a 4 ton load to obtain pre-alloyed powders. The final step is sintering at 950°C for 7 h in a tubular furnace under a controlled atmosphere. X-ray diffraction measurements (XRD), scanning electron microscopy (SEM) analyses, microhardness measurements, friction tests and electrochemical were carried out to characterise the tribological and electrochemical performances of the elaborated specimens. DRX results reveal the formation of four major phases: TiNi, Ti2Ni, TiNi3 and TiNi0.8Cu0.2. Potentiodynamic polarisation tests show the positive effect of adding Cu on corrosion resistance, where the 6% Cu sample exhibits the best corrosion behaviour. Tribological results show a decrease in the coefficient of friction and wear rate with the addition of Cu, compared to the initial state, without Cu addition. The minimum coefficient of friction (0.585) was recorded for the 2% Cu sample, while the minimum wear rate (Ws = 1.06. E−4mm3/N/m) was achieved for the 4% Cu sample.

Efficient removal of amoxicillin, ciprofloxacin, and tetracycline from aqueous solution by Cu-Bi2O3 synthesized using precipitation-assisted-microwave

This study investigates the synthesis and characterization of Cu-Bi2O3 for degradation of antibiotics AMX, CIP, and TC using precipitation-assisted-microwave method at varying concentrations of Cu at 0%, 2%, 4%, 6%, and 8%. The effect of Cu concentration on the structural, morphological, and optical properties were studied by XRD, UV-Vis, and SEM-EDX. The optimal results were obtained by adding 4% Cu to the Bi2O3 matrix. With an energy band gap of 2.32 eV, a crystal size of 37.04 nm, and ?-Bi2O3 and CuBi2O4 phases. The removal efficiency of each antibiotic using the photocatalytic method varies, with AMX at 52.06%, CIP at 61.72%, and TC at 69.44%. Cu-Bi2O3 degraded TC-type antibiotics more rapidly. The high removal efficiency and rapid reaction rate indicate that Cu-Bi2O3 is an effective antibiotic removal agent. This further confirms the fact that the addition of Cu to Bi2O3 material can increase its ability to degrade antibiotics more effective.

Direct evidence from STXM analysis of enhanced oxygen storage capacity in ceria through the addition of Cu and Mg: Correlation of HT-WGS reaction performance

Here, scanning transmission X-ray microscopy (STXM) analysis was utilized to directly present visual evidence of changes in oxygen storage capacity (OSC) when small amounts of an additive were incorporated into CeO2. Specifically, the chemical map measured by STXM analysis differentiated between Cu-rich and Ce-rich areas to derive the proportion of Ce3+. Additionally, we found that the dispersion of Cu significantly influenced the formation of OSC. The findings were applied to the high-temperature water–gas shift reaction for producing high-purity hydrogen from waste-derived syngas, establishing a correlation with catalyst performance. Consequently, the CCM75 (Ce/Mg = 75/25) catalyst demonstrated the highest Cu dispersion and OSC values (6.9 %, 800.3 μmolO/gcat), and it also showed the highest CO conversion (79 % at 450 °C) and stability (−7.7 % at 450 °C after 50 h), attributed to the significant presence of active Cu. This study confirms previously reported interactions between Cu and CeO2 and uncovers the significant roles of Cu and Mg in this catalysis system, providing new understanding of the mechanisms that facilitate OSC improvement.

Solvent‐Free Efficient Hydrogenation of Levulinic Acid over Silicotungstic Acid Promoting the Activity of CuNiAl Catalysts: A Synergistic Effect

AbstractMulti‐metallic catalysts rely on the synergistic effect between metals to perform better catalytic effect in biomass hydrogenation experiments compared with mono‐metallic catalysts. A series of CuNiAl composite metal oxide catalysts promoted by silicotungstic acid (HSiW), which were prepared by co‐precipitation and impregnation methods, were characterized by powder X‐ray diffraction (XRD), N2‐physisorption, scanning electron microscope (SEM) and NH3 program temperature desorption (NH3‐TPD) and pyridine infrared adsorption (Py‐FTIR). Their catalytic performance was evaluated in the hydrogenation of levulinic acid (LA) to prepare γ‐valerolactone (GVL). The results showed that the addition of Cu could improve the hydrogenation activity of Ni, and the addition of HSiW could further increase the amount of acid sites in the catalysts. Both of them could enhance the conversion of LA to some extent. CuNiAl‐5SiW, the par excellence catalyst, relied on the synergistic interactions between metals as well as the Brønsted and Lewis acid active sites to show efficient hydrogenation performance. The CuNiAl‐5SiW catalyst demonstrated 96.9 % conversion of LA and more than 99 % selectivity to GVL under 2 hours of reaction time, 180 °C of reaction temperature, 3.0 MPa of initial hydrogen pressure and solvent‐free conditions.

Simultaneous enhancement of strength and ductility in Al-Zn-Cu casting alloy with trace Mg addition designed by first principle calculation

The Al alloy containing 17 wt% Zn exhibits enhanced strength through Zn precipitation after casting without the need for further aging treatment. DFT (Density Functional Theory) calculations revealed that the addition of Cu and Mg elements to Al-Zn alloy has the potential to stabilize the Zn phase in the Al matrix and reduce the interface energy between the Zn precipitate and Al matrix. Based on these findings, 0.5 wt% Cu and 0.1 wt% Mg were added to the Al-17 wt% Zn alloy. The trace element level of 0.1 wt% Mg addition led to a significant increase in both yield and tensile strength, from 132 to 278 and from 248 to 310 MPa, respectively, compared to the Al-17 wt% Zn alloy with 0.5 wt% Cu. Furthermore, their ductility surpassed 11 %. The trace amount of Mg greatly increased yield and tensile strength, while Cu enhanced the ductility in the Al-Zn alloy after casting without any aging treatment.

Using ethanol and isopropanol as biomass model compounds for understanding bond scission mechanisms over Cu/Mo2N catalysts

The conversion of biomass compounds into fuels and chemicals is an important step towards a more sustainable future. This work combines results from model surfaces and powder catalysts to demonstrate Cu-modified molybdenum nitride (Cu/Mo2N) as a selective catalyst for dehydrogenation of the biomass model compounds, ethanol and isopropanol. Results from model surfaces showed that while Mo2N led to unselective decomposition via both dehydrogenation and dehydration, the addition of Cu increased the dehydrogenation activity and selectivity. DFT calculations showed how Cu influenced the structures of active sites, adsorbate interactions, and thus the product selectivity. Batch reactor studies on corresponding powder catalysts confirmed the trend that Cu modification increased dehydrogenation activity, and in situ X-ray absorption spectroscopy elucidated the Cu oxidation state under reaction conditions. This work demonstrates a strategy for promoting dehydrogenation over Mo2N-based catalysts, as well as the feasibility of using model surfaces to guide the design of industrially relevant catalysts.

A novel biodegradable Zn-0.4Li-0.4Cu alloy with superior strength-ductility synergy and corrosive behavior by laser powder bed fusion

Zinc (Zn) alloys have recently revolutionized and shown promising usage for degradable biomedical implants (BMI). However, due to the low strength of pure Zn, its application in the biomedical industry was limited. In the current research, an innovative biodegradable Zn-0.4Li-0.4Cu alloy produced by laser powder bed fusion (LPBF) with good mechanical properties was investigated. The Zn-0.4Li-0.4Cu alloy showed superior mechanical properties (tensile strength at 296 MPa, yield strength at 260 MPa, and after heat treatment elongation at 8.3 %), a record for biodegradable Zn alloys, as a consequence of grain refinement, second-phase precipitation of intermetallic compounds, and solid solution strengthening. The impacts of Cu and Li on the microstructures, mechanical behaviors, corrosive behavior and deterioration rate of the Zn-0.4Li-0.4Cu alloy were studied. The addition of Cu and inherent fast-cooling rate of the LPBF process are favorable for promoting the nucleation events, leading to the refinement of grains. In addition, the formation of the second-phase precipitates (CuZn4 and ZnLi4) in the matrix was founded to further improve the mechanical properties. Moreover, the alloy showed a consistent degradation manner and a suitable degradation rate of 0.023 mm/year. Based on the findings shown above, the biodegradable Zn-0.4Li-0.4Cu alloy can be a potential candidate for vascular stents and medical applications due to its excellent mechanical properties and adequate degrading behavior.

Study of Microstructure, Morphology and Functional Groups of Titanium Dioxide (Tio2) Impregnated With Copper (Cu)

This research aims to determine the differences in the microstructure, morphology, and functional groups of TiO2 (P-25) after being impregnated with Cu. Cu-impregnated TiO2 samples are synthesized using the impregnation method with TiO2 (P-25) and copper sulfate as precursors. The microstructure and functional groups of TiO2 (P-25) and Cu-TiO2 were investigated using X-ray diffraction (XRD), scanning electron microscope-energy dispersive x-ray (SEM-EDX), and Fourier transform infrared (FTIR) analysis. The lattice parameters (a, b, and c) of the TiO2 sample were found to be a = b = 0.3778 nm, c = 0.9494 nm, and these values increased to a = b = 0.3779 nm, c = 0.9496 nm after the addition of Cu. The distance between the lattices of the TiO2 sample was measured at 0.3505 nm and increased to 0.3509 nm after Cu addition. The average crystallite size of the TiO2 sample was 33 nm, which increased to 43 nm after Cu impregnation. The strain value decreased from 2.76×10^(-3) to 1.82×10^(-3) after Cu addition. SEM results revealed that the morphology of the particles from the Cu-doped synthesis showed agglomeration. The success of Cu doping was confirmed by EDX mapping, which showed the presence of Ti, O, and Cu evenly distributed on the TiO2 surface. The FTIR spectrum indicated that TiO2 (P-25) and Cu-TiO2 particles had absorption peaks at similar wave numbers. However, in the absorption area of 1000 cm^-1 to 1250 cm^-1, new absorption bands affiliated with Cu-O bonds appeared in the Cu-TiO2 sample, resulting from TiO2 vibrations after Cu addition.

Laser cladding Ni60 @ WC/ Cu encapsulated rough MoS2 self-lubricating wear resistant composite coating and ultrasound-assisted optimization

This research aims to broaden the scope of self-lubricating wear-resistant coatings for applications in diverse industries such as automotive, metallurgy, power, and aerospace. Employing laser cladding technology, we successfully fabricated high-performance self-lubricating ceramic composite coatings. A comprehensive investigation was conducted to understand the inhibitory effect of Cu on the thermal decomposition of MoS2, and the study systematically explored the relationship between powder composition, coating structure, and organizational properties. The mechanisms behind friction reduction and wear resistance were unveiled, shedding light on the formation of the MoS2 self-lubricating protective film. Research findings reveal that during the laser cladding process, Cu and Ni undergo solid solution, resulting in the formation of the Cu–Ni alloy phase and crystal refinement. The MoS2 aggregation area exhibits a fine dendritic structure, while the dispersion area showcases coarse dendritic and cellular crystals. The addition of Cu and MoS2 influences the content of the MxCy phase and the thermal decomposition of MoS2. The incorporation of Cu increases the average coating hardness, whereas MoS2 addition decreases it; nevertheless, the Cu/MoS2 coating hardness is enhanced by at least 6.4 %. Cu significantly improves the coating's wear resistance, with a relatively smaller impact on friction reduction. MoS2 functions as a friction-reducing phase during wear, effectively preventing the peeling of hard phases and reducing the friction coefficient. Cu is uniformly distributed in the coating, experiencing solid solution strengthening, reducing adhesive region areas, and minimizing wear debris generation. MoS2, although unevenly distributed, forms intermittent lubricating films on the surface. The lubricating film of the Cu/MoS2 coating remains stable, preventing mutual contact of the friction surface and concurrently reducing the friction coefficient and wear amount. While the study successfully prepared a self-lubricating ceramic coating with excellent wear resistance, some surface quality defects persist. Further optimization of the preparation method was achieved through ultrasound-assisted technology.

Interfacial effects of Cu/Fe3O4 in water-gas shift reaction: Role of Fe3O4 crystallite sizes

Copper-promoted iron oxides are commonly utilized in high-temperature water-gas shift (WGS) reactions. Although the promotional effect of Cu has been previously documented, the nature of the active sites for Cu/Fe3O4 remains debated and the role of the crystallite size of Fe3O4 has not been tackled. In this study, a wide range of Cu/Fe3O4 catalysts were designed by hosting Cu species onto Fe3O4 of two contrasting crystallite sizes (approximately 10 and 160 nm) and by utilizing different preparation methods (ammonia evaporation and deposition-precipitation). The evaluation of their catalytic WGS performances revealed a remarkable and previously undocumented phenomenon: the addition of Cu resulted in universal activity enhancements only for small Fe3O4 crystals, while the larger analogues displayed decreased activity. This peculiar phenomenon can be explained by the creation of Cu–Fe3O4 interfaces present in the iron oxides of small crystallite sizes. Thorough characterizations, such as advanced electron microscopic, in situ powder X-ray diffractions, in situ diffuse reflectance infrared Fourier transform spectroscopy, and computational studies, suggest strong electronic interactions between the different metal species, facilitated reductions of the individual oxides, and more favorable CO activation at the interfacial sites, all accounting for the promoted activity.

Process-induced microstructural variations in laser powder bed fusion of novel titanium alloys: A comprehensive study on volumetric energy density and alloying effects

This study explores the effect of in-situ alloying and volumetric energy density (VED) on the microstructure of Laser Powder Bed Fusion (L-PBF) fabricated Ti alloys. Pure Ti, Ti–5Cu, and Ti–5Cu–1Si (wt%) samples were printed using elemental powders with varying VEDs. This study investigates the influence of VED and Cu/Si additions on the growth restriction factor (Q) and columnar-to-equiaxed transition of the β phase. Pure Ti samples exhibited coarse, prior columnar β grains with an average diameter of 106 μm, and a grain shape factor greater than 3.0. In contrast, both Ti–Cu and Ti–Cu–Si samples displayed a significant fraction of equiaxed prior β grains with a near-spherical morphology. Additionally, Cu/Si addition refined the prior β columnar grains, reducing their average diameter to 37 μm and 25 μm in Ti–Cu and Ti–Cu–Si, respectively. Furthermore, the study reveals a strong dependence of microstructure on VED in the Ti–5Cu–1Si alloy. Higher VED promotes a more uniform distribution of solute elements and a lower thermal gradient, resulting in finer equiaxed β grains with an average diameter of 4.9 μm, compared to samples printed at lower VEDs. The addition of Cu and Si also significantly refined the lath-like α phase and decreased the c/a ratio of the Ti HCP lattice, introducing lattice microstrains in the Ti–Cu and Ti–Cu–Si alloys. These findings demonstrate the potential of in-situ alloying and VED optimization for tailoring microstructures in novel Ti alloys fabricated via L-PBF, paving the way for achieving superior mechanical properties.

Efficient electrocatalytic reduction of nitrate to ammonia using Cu–CeO2 solid solution

Electrocatalytic nitrate reduction reaction (EC-NITRR) is expected to replace Haber-Bosch process for green ammonia (NH3) production. Currently, many catalysts often result in low NH3 yields and low faraday efficiencies due to the lack of active sites. In this study, Cu-doped CeO2 solid solution catalyst was prepared for EC-NITRR using transition metal ions doping. The addition of Cu significantly improved the oxygen vacancy (Ov) concentration of CeO2 and provided more active sites for NO3− catalysis. Meanwhile, the internal charge transfer capability and surface catalytic kinetics of the catalyst are enhanced by the excellent redox capability of Ce3+ and Cu+. Compared with bare CeO2, the NH3 yield of 7% Cu–CeO2 increased by 1.88 times. This work provides new ideas for the design of green and efficient catalysts for EC-NITRR by identifying the role of Cu in the mechanism of doping regulation of CeO2.

Two-phase separation facilitating the ordering of L10-FePt: experimental and thermodynamic investigation on Fe–Pt–Cu phase diagrams

The L10-FePt nanocrystals exhibit unique magnetic and catalytic properties, but suffer from the ordering difficulty. The addition of Cu can facilitate the L10-FePt ordering for some Fe–Pt–Cu alloys, however, the action mechanism is far from being well understood. In this work, a systematic study has been performed to the phase diagrams of the Fe–Pt–Cu system. The isothermal sections at 600 °C, 750 °C and 1000 °C, as well as the partial vertical sections of Fe50Pt50–Cu50Pt50 and Fe50Pt50–Cu, were constructed. An emphasis has been paid to the L10-FePt phase, which has a wide composition range with a solid solubility of Cu up to 40.0 at% at 600 °C. Its order-disorder transition temperature decreases rapidly when deviating from 54 at% Pt, but at different lower rates along (FePt)100-xCux and (Fe50-xCux)Pt50 with the increase of Cu. The ternary miscibility gap which originates from the Fe–Cu side has been studied by both experimental determinations and thermodynamic calculations. The results indicate that, at certain low temperatures, for instance 300 °C, the metastable miscibility gap can expand even up to 45 at% Pt, entering the L10-FePt phase region. An ordering transition mechanism of the L10-FePt phase stimulating by a two-phase separation was thus proposed. For a specially designed disordered Fe–Pt–Cu alloy, a metastable two-phase separation can take place firstly in the annealing process, driving the Cu atoms forming Cu-rich particles, leaving a large number of vacancies in the alloy, and consequently, accelerate the atomic diffusion and stimulate the subsequent L10 ordering transition. These results will provide a new perspective for the composition design of Fe–Pt–Cu catalysts and magnetic recording media.

Tailored Cu-Fe-based oxygen carrier for moderate-temperature chemical looping hydrogen generation from blast furnace gas

Chemical looping hydrogen generation (CLHG) offers a promising solution for producing H2 from industrial off-gas, such as blast furnace gas. However, increasing H2 production capacity of the oxygen carrier (OC) at moderate temperature remains a significant challenge. In this study, a novel Cu-Fe-based OC is tailored for moderate-temperature CLHG from blast furnace gas. The results demonstrates that the tailored OC exhibits a superior H2 production capacity of 12.99 mmol·g−1 at 550 °C, which is 6.5 times higher than that of Fe2O3 at the same temperature. The addition of Cu leads to the formation of oxygen defects, which facilitate the migration of lattice oxygen, thereby the activity of the OC is enhanced. Furthermore, cyclical experiments demonstrates that O2-assisted regeneration strategy can effectively suppress the segregation of Cu during the cycling process, and the tailored OC shows good stability during 10 redox cycles. No additional separation process was required and the purity of the hydrogen was higher than 99%. The findings here open a new avenue for efficient CLHG from industrial off-gas at moderate operation temperature.