Search Results (141)

Bimetals—materials composed of two metal components with dissimilar standard reduction–oxidation (redox) potentials—offer unique electronic, optical, and catalytic properties, surpassing monometallic systems. These materials exhibit not only the combined attributes of their constituent metals but also new and novel properties arising from their synergy. Although many reviews have explored the synthesis, properties, and applications of bimetallic systems, none have focused exclusively on iron (Fe)- and aluminum (Al)-based bimetals. This systematic review addresses this gap by providing a comprehensive overview of conventional and emerging techniques for Fe-based and Al-based bimetal synthesis. Specifically, this work systematically reviewed recent studies from 2014 to 2023 using the Scopus, Web of Science (WoS), and Google Scholar databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, and was registered under INPLASY with the registration number INPLASY202540026. Articles were excluded if they were inaccessible, non-English, review articles, conference papers, book chapters, or not directly related to the synthesis of Fe- or Al-based bimetals. Additionally, a bibliometric analysis was performed to evaluate the research trends on the synthesis of Fe-based and Al-based bimetals. Based on the 122 articles analyzed, Fe-based and Al-based bimetal synthesis methods were classified into three types: (i) physical, (ii) chemical, and (iii) biological techniques. Physical methods include mechanical alloying, radiolysis, sonochemical methods, the electrical explosion of metal wires, and magnetic field-assisted laser ablation in liquid (MF-LAL). In comparison, chemical protocols covered reduction, dealloying, supported particle methods, thermogravimetric methods, seed-mediated growth, galvanic replacement, and electrochemical synthesis. Meanwhile, biological techniques utilized plant extracts, chitosan, alginate, and cellulose-based materials as reducing agents and stabilizers during bimetal synthesis. Research works on the synthesis of Fe-based and Al-based bimetals initially declined but increased in 2018, followed by a stable trend, with 50% of the total studies conducted in the last five years. China led in the number of publications (62.3%), followed by Russia, Australia, and India, while Saudi Arabia had the highest number of citations per document (95). RSC Advances was the most active journal, publishing eight papers from 2014 to 2023, while Applied Catalysis B: Environmental had the highest number of citations per document at 203. Among the three synthesis methods, chemical techniques dominated, particularly supported particles, galvanic replacement, and chemical reduction, while biological and physical methods have started gaining interest. Iron–copper (Fe/Cu), iron–aluminum (Fe/Al), and iron–nickel (Fe/Ni) were the most commonly synthesized bimetals in the last 10 years. Finally, this work was funded by DOST-PCIEERD and DOST-ERDT. Full article

CuCrZr/GH4169 multi-material structures combine the high thermal conductivity of copper alloys with the high strength of nickel-based superalloys, making them suitable for aerospace components that require efficient heat dissipation and high strength. However, additive manufacturing of such dissimilar metals faces challenges, with each laser powder bed fusion (LPBF) and laser directed energy deposition (LDED) process having its limitations. This study employed an LPBF-LDED integrated additive manufacturing (LLIAM) approach to fabricate CuCrZr/GH4169 components. CuCrZr segments were first produced by LPBF, followed by LDED deposition of GH4169 layers using optimized laser parameters. The microstructure, composition, and mechanical properties of the fabricated components were analyzed. Results show a sound metallurgical bond at the CuCrZr/GH4169 interface with minimal porosity and cracks (typical defects at the interface), achieved by exceeding a threshold laser energy density. Elemental interdiffusion forms a 100–200 μm transition zone, with a smooth hardness gradient (97 HV0.2 to 240 HV0.2). Optimized specimens exhibit tensile failure in the CuCrZr region (234 MPa), confirming robust interfacial bonding. These findings demonstrate LLIAM’s feasibility for CuCrZr/GH4169 and underscore the importance of balancing thermal conductivity and mechanical strength in multi-material components. These findings provide guidance for manufacturing aerospace components with both high thermal conductivity and high strength. Full article

Given by their low weight and favorable combination of properties, Al-Fe-Si-based intermetallic and duplex alloys are widely used in mechanical engineering. The use of aluminum scrap for their production imparts the necessity for a thorough study of the impacts of presence of impurity/alloying elements on the phase composition. By this reason, individual impacts of the impurity/alloying elements present in the majority of commercial alloys on phase compositions of the alloys were studied herein. Particular emphasis was on the formation of the α phase and features of the α↔β transformation, as well as on their effects on the solidus, liquidus, and phase transformation temperatures. Modeling was used to study the synergistic effect of the simultaneous introduction of 12 elements into aluminum. According to the results, magnesium, copper, and nickel have a tendency to form combined intermetallic phases, and beryllium, as a structurally free element, forms precipitates even at minimum concentrations. Verification of the modelled results was performed using a real alloy prepared experimentally from commercially available raw materials. The comparison of the results provided by computer modeling and the actual phase composition showed sufficient agreement. The herein acquired results contribute to a deeper understanding of the features of phase transitions occurring during alloying of aluminum alloys and will also be useful for predicting microstructures and phase compositions of intermetallic alloys. This research has potential to inspire further development in materials science and engineering. Full article

REBCO coated conductors have a multi-layer structure, and the outer encapsulation layer is generally made of non-magnetic copper material. This paper proposes a new structure of REBCO tape, which replaces the copper layer with magnetic material to explore its transport loss and magnetization loss. The results indicate that copper-encapsulated REBCO tapes have lower transport losses at low currents, while tapes encapsulated with strong magnetic nickel alloy materials have the highest transport losses. At high transport currents, the transport losses of REBCO tapes encapsulated with different materials are almost equal. At low fields, the magnetization loss of the tape encapsulated with strong magnetic nickel alloy is lower, while the magnetization loss of the tape encapsulated with copper is the highest, due to the magnetic shielding effect of the magnetic material. Under high-field conditions, the difference in magnetization loss between magnetic material-encapsulated tapes and copper-encapsulated tapes decreases. Full article

Copper–nickel alloys are widely applied in marine engineering due to their excellent mechanical properties and corrosion resistance. This study investigates the effect of chromium (Cr) on the erosion–corrosion behavior of copper–nickel alloys through erosion–corrosion experiments. The results indicate that the alloy containing Cr exhibits enhanced erosion–corrosion resistance. The addition of Cr reduces the corrosion rate of the copper–nickel alloy from 0.206 mm/a to 0.060 mm/a. This improvement in corrosion resistance is mainly attributed to the formation of (Ni/Fe)₃Cr phases, which enhance the alloy’s strength and further improve its erosion resistance. Furthermore, Cr increases the electrochemical resistance of the corrosion products. Full article

To address the critical applications of heterogeneous structures involving nickel-based superalloys (IN718) and copper alloys (CuSn10) under extreme operating conditions, and to address the limitations of traditional joining techniques in terms of interfacial brittleness and geometric constraints, this study employs Laser Powder Bed Fusion (LPBF) technology, specifically multi-material LPBF (MM-LPBF). By precisely melting IN718 and CuSn10 powders layer by layer, the study directly fabricates multi-material IN718/CuSn10 joint specimens, thereby simplifying the complexity of traditional joining processes. The research systematically investigates the interfacial microstructure and mechanical property evolution laws and underlying mechanisms. It reveals that sufficient element diffusion and hardness gradients are present at the IN718/CuSn10 interface, indicating good metallurgical bonding. However, due to significant differences in thermophysical properties, cracks inevitably appear at the interface. Mechanical property tests indicate that the strength of the IN718/CuSn10 joint specimens falls between that of IN718 and CuSn10, but with lower elongation, and fractures primarily occur at the interface. This research provides theoretical support for establishing a process database for LPBF formed of nickel–copper heterogeneous materials, advancing the manufacturing technology of aerospace multi-material components. Full article

This study systematically investigated the effects of tailored heat treatments on the microstructural evolution, mechanical properties, and erosion–corrosion resistance of Cu-10Ni-3Al-1.8Fe-0.8Mn alloy. Four heat treatment conditions—as-cast (AC-1); homogenized (H-2); and deformation–aged at 500 °C (D-3) and 750 °C (D-4)—were applied to elucidate the interplay between microstructure and performance. The D-3 specimen, subjected to deformation followed by aging at 500 °C for 0.5 h, demonstrated superior properties: a Vickers hardness of 118 HV5 (83.3% higher than H-2) and an erosion–corrosion rate of 0.0075 mm/a (84.1% reduction compared to H-2). These enhancements were attributed to the uniform dispersion of nanoscale Ni₃Al precipitates within the matrix, which optimized precipitation strengthening and reduced micro-galvanic corrosion. The D-3 specimen also formed a dense, crack-free Cu₂O corrosion product film with a flat matrix interface, confirmed by SEM cross-sectional analysis and electrochemical impedance spectroscopy (EIS), exhibiting the highest charge transfer resistance and film impedance. Full article

In order to solve the problem of poor weld quality caused by brittle metal compounds in the welding of dissimilar metals between aluminum and steel, a pre-welding treatment method of prefabricated copper–nickel binary coating between aluminum and steel has been proposed. Laser lap welding tests and weld performance tests were conducted using 6061 aluminum alloy and DP590 duplex steel with a thickness of 0.5 mm as base materials, with steel on top and aluminum on bottom. The research results indicate that the prefabricated copper–nickel binary coating can effectively suppress the formation of brittle phase compounds of Fe and Al; the increase of copper and nickel elements is beneficial for the formation of tough compounds such as (Fe, Cu, Ni)₃Al, (Fe, Cu, Ni)Al₃, and CuAl₅ in the weld zone; when the thickness of the copper coating is 155 μm and the thickness of the nickel coating is 110 μm, the mechanical properties of the aluminum steel lap welding seam are the best, and the maximum shear force that can be withstood is 208.09 N, which is 56% higher than uncoated sample. Full article

High chromium cast iron (HCCI) is widely used in the manufacturing of equipment parts in the fields of mining, cement, electric power, metallurgy, the chemical industry, and paper-making because of its excellent wear and corrosion resistance. Although the microstructure and properties of HCCI can be modified by controlling the casting and heat treatment process, alloying is still the most basic and important method to improve the properties of HCCI. There are about 14 common alloying elements in HCCI, among which nickel, copper, and manganese are typical austenite stabilizing elements, which can increase austenite content and matrix electrode potential. The addition of elements such as silicon, nitrogen, boron, and rare earth (RE) is often small, but it has a significant effect on tailoring the microstructure, thereby improving wear resistance and impact toughness. It was thought that after years of development, the research on the role of the above elements in HCCI was relatively complete, but in the past 5 to 10 years, there has been a lot of new research progress. Moreover, the current development situation of HCCI is still relatively extensive, and there are still many problems regarding the alloying of HCCI to be further studied and solved. In this paper, the research results of austenitic stabilizing elements and modifying elements in HCCI are reviewed. The existing forms, distribution law of these elements in HCCI, and their effects on the microstructure, hardness, wear resistance, and corrosion resistance of HCCI are summarized. Combined with the current research situation, the future research and development direction of HCCI alloying is prospected. Full article

This study examines the diffusion behavior, thermal stability, and mechanical properties of the bimetallic interface between additively manufactured copper alloy GRCop-42 and nickel alloy 625 (UNS N06625) following elevated temperature exposure at service-relevant conditions for high-temperature superalloys. The copper alloy was additively manufactured using laser powder bed fusion. The nickel alloy was subsequently deposited directly onto the copper alloy using powder-based directed energy deposition. The samples were held at a temperature of 816 °C (1500° F) for varying exposure times between 50 and 500 h. Significant material loss (averaging ~430$\mathsf{\mu }\mathrm{m}$ at 50 h and ~1830 $\mathsf{\mu }\mathrm{m}$ at 500 h) due to oxidation was noted in the copper alloy. The bondline interface was examined using optical microscopy as well as electron microprobe analysis. Composition maps from the electron microprobe showed the formation of oxides in the copper alloy and Laves phase in the nickel alloy at thermal exposure times of 200 h or more. By analyzing diffusion across the bondline, this study demonstrates the ability of machine learning-based diffusion models to predict diffusion coefficients of copper into alloy 625 ($2.38\times {10}^{-12}\mathrm{c}{\mathrm{m}}^2/\mathrm{s}$) and of nickel into GRCop-42 ($1.90\times {10}^{-12}\mathrm{c}{\mathrm{m}}^2/\mathrm{s}$) and the ability of commercially available diffusion code (Pandat) to provide reasonably accurate diffusion profiles for this system. Tensile and fatigue tests were performed in the as-built and 200 h thermal exposure conditions. The thermally exposed samples exhibited an average 18.6% reduction in yield strength compared to the as-built samples. Full article

The relevance of the study is related to the need to join dissimilar copper and nickel alloys by laser direct energy and material deposition (LDED). The purpose of research is studying the distribution of elements, structure, and properties of contact zone of nickel-based super alloy and CuCr1 bronze obtained by direct energy and material deposition with preliminary formation of relief of contact surface. For the purposes of research, samples were made from UNS C18200 copper alloy CuCr1 without relief, with a relief of 0.5 mm depth, and with a relief of 1 mm depth. The Ni₅₀Cr₃₃W_4.5Mo_2.8TiAlNb (EP648) alloy powder was deposited onto the bronze samples with a micro-relief. The deposition was produced by direct injection of energy and material. The influence of interphase interaction of CuCr-chromium carbide system on the possibility of initiation of a crack in the area of carbide secretions is not significant and does not exceed 3.1% according to CIC criterion from the background level for CuCr1 (CIC = 1.54% for CuCr1-Al₄C₃ interface and CIC = 3.1% for CuCr1-Cr₂₃C₆ interface). An X-ray analysis revealed the presence of tensile residual macro-stresses, arising from differences in thermal expansion coefficients in the CuCr1-EP648 interface area, which may be the main cause of crack formation. Cracks are generated and run along the grain boundaries, on which traces of excretion are visible. The contact surface in the CuCr1-EP648 interface area has no visible defects, which indicates the good adhesion of materials when applying an initial layer of EP648 by LDED. The presence of a 0.5-mm micro-relief on CuCr1 has a positive effect on the strength of the connection, as it increases the surface area of the contact CuCr1-EP648 and therefore reduces the contact stress of the breakout. Full article

This paper reviews the research progress of Cu-Ni-Si alloy as a lead frame material for ICs. Cu-Ni-Si alloy is considered a strong candidate for lead frame materials due to its excellent mechanical properties and adequate electrical conductivity. The types and properties of Cu-Ni-Si alloys are then discussed in detail, emphasizing strength and conductivity as two key indicators for evaluating the properties of Cu-Ni-Si alloys, as well as the challenges posed by their inverse correlation. The preparation methods of Cu-Ni-Si alloy, including conventional melting, vacuum melting, and jet forming, are also discussed, and the effects of different casting techniques on the alloy’s properties are analyzed. Furthermore, the conductivity and strengthening mechanisms of Cu-Ni-Si alloy, including solid solution strengthening, second phase strengthening, and deformation strengthening, are discussed. The effects of the Ni-Si atomic ratio, trace elements, and rare earth elements on the alloy’s properties are also discussed. Finally, the current research status of Cu-Ni-Si alloy is summarized, and future research directions are identified, including the development of new preparation technologies, establishment of systematic databases, and promotion of green manufacturing and sustainable alloy development. Full article

Coal fly ash zeolites with Sodalite structure were synthesized by ultrasound-assisted double stage fusion-hydrothermal synthesis. Monometallic Ni and bimetallic Ni–Cu supported catalysts with 5 wt.% Ni and different copper contents of 1.5, 2.5 and 5.0 wt.% Cu were prepared by post-synthesis incipient wetness impregnation. The catalysts were characterized by X-ray powder diffraction, N₂ physisorption, transmission electron microscopy (TEM), Mössbauer spectroscopy and H₂ temperature programmed reduction analysis. It was found that crystalline Cu⁰ and Ni_xCu_y intermetallic nanoparticles were formed in the reduced powder and 3D printed catalysts and that they affected the reducibility of the catalytically active nickel phase. Three-dimensionally printed 5Ni2.5Cu/Sodalite catalysts were prepared via modification with metals before and after 3D printing for comparative studies. The powder and 3D printed catalysts were studied in the lignocellulosic biomass-derived levulinic acid (LA) to γ-valerolactone (GVL). The formation of NiCu alloy, which is found on the powder and 3D printed catalysts, favors their catalytic performance in the studied reaction. In contrast with powder catalysts, the preservation of the Sodalite structure was detected for all 3D printed samples and was found to have a positive influence on the metal dispersion registered in the 3D spent catalysts. The powder 5Ni2.5Cu/Sodalite catalyst showed the highest LA conversion and high GVL yield at 150 °C reaction temperature. Three-dimensionally printed catalysts show more stable catalytic activity than powder catalysts due to the preservation of the zeolite structure and metal dispersion. Full article

Fused filament fabrication (FFF) is the most widespread and versatile material extrusion (MEX) technique. Although powder-based systems have dominated the metal 3D printing landscape in the past, FFF’s popularity for producing metal parts (“metal FFF”) is growing. Metal FFF starts from a polymer–metal composite feedstock and proceeds through three primary stages, namely shaping (i.e., printing), debinding, and sintering. As critically discussed in the present review, the final quality of metal FFF parts is influenced by the characteristics of the composite feedstock, such as the metal loading, polymer backbone, and presence of additives, as well as by the processing conditions. The literature shows that a diverse array of metals, including steel, copper, titanium, aluminium, nickel, and their alloys, can be successfully used in metal FFF. However, the formulation of appropriate polymer binders represents a hurdle to the adoption of new material systems. Meanwhile, intricate geometries are difficult to fabricate due to FFF-related surface roughness and sintering-induced shrinkage. Nonetheless, the comparison of metal FFF with other common metal AM techniques conducted herein suggests that metal FFF represents a convenient option, especially for prototyping and small-scale production. Whilst providing insights into the functioning mechanisms of metal FFF, the present review offers valuable recommendations, facilitating the broader uptake of metal FFF across various industries. Full article

The electrolysis of water is one of low-cost green hydrogen production technologies. The main challenge regarding this technology is designing and developing low-cost and high-activity catalysts. Herein, we present a strategy to fabricate flexible electrocatalysts based on nickel–iron (NiFe) alloy coatings. NiFe coatings were plated on the flexible copper-coated polyimide surface (Cu/PI) using the low-cost and straightforward electroless metal-plating method, with morpholine borane as a reducing agent. It was found that Ni₉₀Fe₁₀, Ni₈₀Fe₂₀, Ni₆₀Fe₄₀, and Ni₃₀Fe₇₀ coatings were deposited on the Cu/PI surface; then, the concentration of Fe²⁺ in the plating solution was 0.5, 1, 5, and 10 mM, respectively. The morphology, structure, and composition of Ni_xFe_y/Cu/PI catalysts have been examined using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and inductively coupled plasma–optical emission spectroscopy (ICP-OES), whereas their activity has been investigated for hydrogen evolution (HER) and oxygen evolution (OER) reactions in 1 M KOH using linear sweep voltammetry (LSVs). It was found that the Ni₈₀Fe₂₀/Cu/PI catalyst exhibited the lowest overpotential value of −202.7 mV for the HER, obtaining a current density of 10 mA cm⁻² compared to Ni₉₀Fe₁₀/Cu/PI (−211.9 mV), Ni₆₀Fe₄₀/Cu/PI (−276.3 mV), Ni₃₀Fe₇₀/Cu/PI (−278.4 mV), and Ni (−303.4 mV). On the other hand, the lowest OER overpotential (344.7 mV) was observed for the Ni₆₀Fe₄₀/Cu/PI catalyst, obtaining a current density of 10 mA cm⁻² compared to the Ni₃₅Fe₆₅ (369.9 mV), Ni₈₀Fe₂₀ (450.2 mV), and Ni₉₀Fe₁₀ (454.2 mV) coatings, and Ni (532.1 mV). The developed Ni₆₀Fe₄₀/Cu/PI catalyst exhibit a cell potential of 1.85 V at 10 mA cm⁻². The obtained catalysts seem to be suitable flexible catalysts for HER and OER in alkaline media. Full article