With the growing demand for high-performance thermal management devices, achieving efficient and reliable joining between 3D-printed SiC-reinforced Ti6Al4V composite (3DP-SiC/TC4) and SiC ceramic presents a critical challenge. To enhance the interfacial thermal conductivity, femtosecond laser treatment (FLT) was applied to the SiC ceramic, aiming to construct a uniform striated microstructure. AgCuTi braze was employed to join 3DP-SiC/TC4 with femtosecond laser-treated SiC ceramic (FLT-SiC). The interfacial reaction mechanisms, microstructural evolution, and thermomechanical property optimization were systematically investigated. Based on a series-parallel thermal resistance model, it was revealed that the FLT significantly reduce interfacial thermal resistance by increasing the effective contact area and promoting metallurgical joining. The FLT influences the synergistic effect between geometric morphology and chemical joining. At 0.63 W, a positive synergy between geometric (gain factor ξgeo = 1.083) and interfacial chemical (κchem = 1.087) contributions was achieved. The brazing temperature regulated the extent of interfacial reactions, with 850 ℃ yielding a dense microstructure and optimal properties. The optimal parameters were identified as a laser fluence of 0.63 J/cm2 and a brazing condition of 850 ℃ for 10 min. Under these conditions, the joint exhibited a shear strength of 46.5 ± 2.4 MPa and a thermal conductivity of 24.6 W·m-1·K-1 at 600 ℃. This study provides a novel approach for joining dissimilar materials in thermal management applications, leading to a significant enhancement in the thermal and mechanical performance of the joint.

Heterogeneous alloy designs can significantly enhance the mechanical properties of metallic materials through synergistic effects. In this work, the cold spray additive manufacturing (CSAM)-assisted brazing is proposed to significantly improve the mechanical properties of Cf/C and superalloy joint. The CSAM process promotes the atomic diffusion and metallurgical reaction between the interlayer and superalloy substrate. The findings indicate that the diffusion of Fe, Cr, Ni and Ti within brazing seam promotes the formation of a novel dual-phase heterogeneous structure, comprising a Cr-rich σ phase and a Ni3Ti phase. The σ and Ni3Ti dual-phase heterogeneous structure significantly improves shear strength through a synergistic strengthening mechanism, achieving an effective combination of strength and toughness. The ductile Ni3Ti phase enhances the deformation capacity, while the hard σ phase serves as a continuous barrier to dislocation movement, thereby significantly enhancing the mechanical properties of the brazed joint. The highest shear strength of the Cf/C and superalloy brazed joint reaches 20.9 MPa using a CSAM NiTi75 interlayer, compared to only 6.1 MPa for the joint brazed with conventional NiTi75 powder filler. This work demonstrates the significant potential of CSAM-assisted brazing to enhance the mechanical properties of brazed joints, offering a novel approach to directly prepare brazing interlayers from metal powders.

ABSTRACT The reliable integration of superconducting alloys with dielectric substrates is a challenge in the fabrication of advanced cryogenic devices. In this study, a novel Sn‐Bi‐In‐Ga‐Zn quinary solder doped with amino‐functionalized carbon quantum dots (N‐CQDs) was developed to realize the robust joining of Niobium‐Titanium (NbTi) alloy and fused quartz. The impact of N‐CQDs on the interfacial microstructure, mechanical integrity, and superconducting properties was investigated. Results demonstrate N‐CQDs act as “dual‐functional bridges” at the hetero‐interface. The shear strength of the N‐CQD doped joint reached 51.5 MPa at room temperature, a 51.3% enhancement over the untreated joint. This strengthening is attributed to the formation of a covalent siloxane anchoring network (Si─O─Si) on the quartz side and strong amino‐metal coordination on the metallic side, per XPS and FTIR analyses. Furthermore, the self‐field critical current density (Jc) of the joint at 4.2 K was improved by ∼33.3% to 6.4 × 10 5 A/cm −2 . First‐principles density functional theory calculations reveal that amino functionalization significantly increases the interfacial binding energy and enhances the electronic density of states near the Fermi level. Together with the low‐temperature V – I measurements showing a reduced apparent joint/interface resistance, these results suggest improved interfacial electronic coupling and superconducting transport across the joint.

The demand for multi-band optical transmission makes it challenging for a single material to meet the requirements for fabricating radome windows, with the continuous advancement of radar technology. Herein, NaOH thermal corrosion combined with AgCuInTi filler was employed to address the poor wettability of SiO2f/SiO2 composites, enabling low-stress, high-strength joining with sapphire. The corrosion products enhanced the surface energy of the SiO2f/SiO2 and promoted interfacial reactions, thereby facilitating the wetting and spreading of AgCuInTi on the composites' surface, ultimately reducing the contact angle from 71 degrees to 33 degrees. The typical microstructure of the joint was characterized as: alpha-Al2O3/Ti2O + Cu3Ti3O/Ag(s,s) + Cu(s,s)/Cu3Ti3O + Ti5Six (x = 2, 3, and 4) + Na2Ti9O19/SiO2f/SiO2, achieving a gradient transition in the coefficient of thermal expansion across the brazed seam. Therefore, a maximum shear strength of 52 MPa was achieved when the joint was brazed at 820 degrees C for 10 min with a corrosion time of 10 min, which is 2.5 times higher than that of the joint without surface modification. (c) 2025 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Joining C/C composites to Ni-based superalloys can obtain integrated structures with superior comprehensive performance. This study presents a novel inactive brazing strategy that employed a CuPd high-temperature filler combined with a pre-fabricated chromium carbide (Cr-C) modification layer. The interfacial microstructure evolution, formation mechanisms, and mechanical properties of the inactive brazing joints were systematically investigated. A sound joint of C/C composites and Ni-based superalloys was obtained at the brazing temperature of 1180 degrees C for 10 min. The Cr-C modification layer enabled the wetting of the inactive CuPd filler on the C/C composites, avoiding detrimental reactions within the brazed seam using the active filler. For the first time, a lamellar Cu-Ni-Pd microstructure, primarily composed of ductile (Cu, Ni)Pd and (Cu, Ni)3Pd phases, was observed in this work. The joint shear strength tested at room temperature and 800 degrees C can reach 35.1 MPa and 24.7 MPa, respectively. The joint failure occurred at the side of the C/C composites, which was the weak region of the joint. This work provides an effective high-temperature inactive brazing strategy for poorly wettable carbon materials.

With the decreasing operating temperatures of solid oxide fuel cells (SOFCs), metallic components, such as interconnects and supports, have become critical to their structural integrity. Chromium-containing alloys are particularly promising for these applications due to their low cost, excellent electrical conductivity, and manufacturability. However, Cr evaporation and subsequent deposition onto the cathode—commonly referred to as Cr-poisoning—compromises cathode performance and reduces SOFC lifespan. To mitigate this issue, protective coatings, primarily transition metal oxides with perovskite or spinel structures, are applied to Cr-containing alloys. Among these, Mn-Co and Mn-Cu spinels stand out for their ability to suppress Cr diffusion, maintain low area-specific resistance (ASR), and achieve coefficients of thermal expansion (CTE) compatible with other SOFC components. This review examines the influence of doping elements, specifically transition metals and rare earth elements, on the performance of Mn-Co spinel coatings. Key aspects analyzed include improvements in ASR, CTE, and the coatings’ capacity to inhibit Cr diffusion, which collectively enhance the durability and reliability of SOFCs. Additionally, the mechanisms underlying these improvements are analyzed, alongside discussions on current challenges and future research directions for optimizing SOFC protective coatings.

Joining aluminum alloy to graphite addresses the urgent need for efficient heat dissipation in electronic devices. This study systematically investigates the process of metallizing graphite surfaces using the AgCuTi filler, and analyzes the influence of temperature on the interface and surface characteristics. The study reveals that needlelike TiC phases are formed on the as-metallized layer surface at 900 degrees C to 950 degrees C. Subsequently, the as-metallized graphite is brazed to 3D printed 6061 aluminum alloy using the Al-Si-Mg filler, and the microstructure and properties of the joint are analyzed. Results indicate that the joint region mainly contains Al(s,s), zeta-Ag2Al, theta-Al2Cu, TiC, Al(s,s) + zeta, and (Al,Si)(3)Ti. The shear strength of the 3D printed 6061 aluminum alloy/graphite joints brazed from 560 degrees C to 590 degrees C remains relatively stable at about 40 MPa. The thermal conductivity of the as-brazed joints is significantly higher than that of the unbrazed joints. The brazing seam establishes efficient heat transfer pathways from the aluminum alloy to the graphite, improving the thermal conductivity of the joint. The joint brazed at 590 degrees C for 10 min achieves the highest thermal conductivity of 151.5 W.m(-1).K-1 at room temperature and 120.4 W.m(-1).K-1 at 500 degrees C. This study provides an important reference for the application of brazing technology for 3D printed alloy and carbon materials in advanced thermal management systems.

Ceramic-reinforced aluminum matrix composites possess exceptional properties, which makes them promising candidates for a wide range of applications. However, the brittle Al4C3 phases, which can severely deteriorate the properties of the joint, are often formed in the joint obtained using conventional fusion welding techniques. In this study, an ultrafast laser welding approach is adopted for the first time to join aluminum matrix composites reinforced with 45 vol.% SiC particles. The achieved joints appear to be sound, free from macroscopic defects, and the four-point bending strength of the joint can reach 321 MPa. The effects of laser power and welding speed on the microstructure and mechanical properties are systematically examined. Comprehensive characterization reveals that, unlike conventional laser welding, no brittle and hydrolyzable Al4C3 phase is detected in the welding seam. Instead, the ultrafast laser irradiation promotes the decomposition of SiC particles, which subsequently react with molten aluminum to form nanoscale Al4SiC4 phases. These precipitates are uniformly dispersed throughout the matrix, thus enhancing the joint performance.

The rising demand for high-end equipment manufacturing across the energy, electronics, and aerospace industries has necessitated the development of effective methods for joining dissimilar materials, particularly metals. Dissimilar metal brazing is a notable joining technique owing to its advantages such as low joining temperatures, efficient sealing capability, and applicability to complex structures; it is therefore a central topic in materials processing research. However, dissimilar metal brazing faces significant technical challenges that impede its broader industrial use. Differences in the physical and chemical properties of the base materials, such as melting points, thermal expansion behaviors, and chemical reactivities, can cause problems such as poor wetting of filler metals, generation of residual stresses (leading to joint cracking), and the formation of brittle intermetallic compounds that degrade mechanical strength. Additionally, base materials with irregular shapes further complicate the brazing process, leading to uneven heat distribution, misalignment, and difficulties in achieving effective filler-metal wetting. In this review, the key challenges and underlying mechanisms in dissimilar metal brazing are examined. Current strategies for improving brazability, including surface modification techniques, innovations in high-performance filler metals, and optimization of process parameters, are also systematically reviewed. This review also addresses issues arising from component shape and size differences and proposes viable solutions. Finally, future directions for dissimilar metal brazing are explored, highlighting the potential of intelligent process control systems and the development of environmentally sustainable brazing materials.

High-entropy alloys (HEAs) offer exceptional properties for advanced applications, yet reliable joining techniques remain challenging. This study investigates the microstructure and mechanical properties of Al0.3CoCrFeNi HEA brazed with a TiZrNiCu filler at 960 degrees C for 10 min. The TiZrNiCu filler, characterized by an amorphous structure with a melting point at similar to 835 degrees C, ensures thermal compatibility with the HEA. The optimal joint exhibits a balanced microstructure comprising Ti-2(Ni, Cu) intermetallic compounds (IMCs), C15 Laves phases, Ti (s, s) solid solution, sigma phases, and body-centered cubic (BCC) solid solution phases. Room-temperature shear strength peaks at similar to 153 MPa under these conditions, demonstrating a tradeoff between strength and ductility. Microstructural evolution reveals Ti/Cu diffusion from the filler, elemental redistribution driven by base-metal/IMC interactions, and the formation of solid solution and IMC phases. Fracture analysis indicates that 10-min brazing minimizes brittle phases while maintaining a balanced microstructure. This work establishes TiZrNiCu as a promising medium-entropy brazing filler for HEAs, balancing process efficiency and joint performance.

Niobium alloy and nickel-based superalloy exhibit high strength and remarkable corrosion resistance, joining them to fabricate composite structures could help to realize their potential. Nevertheless, research attention devoted to the joining of niobium alloy with nickel-based superalloy remains scarce. This study investigates direct diffusion bonding of these two materials. The microstructure of the joint is characterized in detail, with the typical joint microstructure being identified as GH4099 / (Ni, Cr)ss + Ni3Nb + Cr2Nb / Ni3Nb / Ni6Nb7 / Nb alloy. With holding time fixed at 60min and diffusion pressure maintained at 15MPa, the effects of diffusion bonding temperature on the microstructure and mechanical properties of joints are examined within the range of 900-1150 ℃. An increase in bonding temperature results in the formation of different intermetallic compounds within the joint. The primary cause of joint fracture is the presence of Cr2Nb and Ni6Nb7. The tensile strength of the joint initially increases and then decreases with increasing temperature, reaching a maximum value of 204MPa. This work expands the range of methods for joining niobium alloys to nickel-based superalloys, enabling bonding without the introduction of additional elements.

Nickel-based superalloys, represented by GH4169, are extensively used in the aerospace industry due to their excellent high-temperature strength and corrosion resistance. However, the formation of excessive brittle intermetallic compounds during wide gap brazing often compromises joint integrity. In this study, two novel boron-and silicon-free High-entropy alloy fillers, Co20Ni20Fe5Mn30Cu20Al5 and Co20Ni20Fe5Mn30Cu20Al2Ti3, were developed to improve the strength and toughness of brazed GH4169 joints. The interfacial microstructure evolution, brazing mechanisms, and mechanical properties of the joints brazed at 1200 °C with different holding times were systematically investigated. The results revealed that in the athermal solidification zone (ASZ), the Co20Ni20Fe5Mn30Cu20Al5 filler exhibited intergranular segregation, which was accompanied by the formation of Cu-rich phases. In contrast, the addition of Ti in Co20Ni20Fe5Mn30Cu20Al2Ti3 was associated with the formation of Ti–rich segregated phases and in-situ TiC phases. The presence of TiC phases appeared to restrict grain boundary migration, which corresponded to significant grain refinement within the brazed seam. The Co20Ni20Fe5Mn30Cu20Al2Ti3 brazed joint exhibits enhanced high-temperature tensile strength and a refined microstructure. Its average room-temperature tensile strength reaches 765.7 MPa, and its high-temperature tensile strength at 850 °C remains as high as 259.08 MPa.

High-density power electronics requires efficient thermal substrates to dissipate heat and extend the lifespan of devices. In this study, a high-thermal-conductivity SiC/graphene heterostructure was successfully fabricated by vacuum brazing using AgCuTi filler. A nanoscale transition layer was formed at the brazed joint, achieving atomic-level bonding with both the substrates. Based on interatomic bonding effects, highly efficient phonon transport channels were formed in the joint region, significantly enhancing the directional heat flow and overall thermal transmission efficiency. The SiC/graphene heterostructure substrate showed high thermal performance with an in-plane thermal conductivity of 201.59 W/(m center dot K), which is 40 % higher than that of unmodified SiC. The peak heating rate of the brazed sample, 1.8 degrees C/s, is nearly 300 % higher than that of unmodified SiC. Thus, surface modification of SiC heat-dissipation substrates with graphene offers a novel approach for developing multifunctional thermal substrates.

The hardness and brittleness of transparent ceramic make it difficult to be prepared in large scale and limit its application. This paper tries to solve this problem from the perspective of realizing its own reliable joining. Without interlayer and preheating, MgAl2O4 transparent ceramics have been directly welding by ultrashort pulse laser for the first time. The typical structure of the joint was systematically characterised, it can be found that at the bonding area, parts of MgAl2O4 crystals were transformed into amorphous. Under the optimal welding parameters (laser power: 550 mW, scanning speed: 0.1 mm/s), the joint achieved a maximum shear strength of approximately 28 MPa. This paper provides a new methodology for MgAl2O4 transparent ceramics joining, owning high efficiency and simplicity, which makes efforts for broadening the application of transparent ceramics.

Polycrystalline cubic boron nitride (PCBN) ceramics have been successfully joined with M42 steel via partial transient liquid phase (PTLP) bonding. To advance joint quality, this study systematically investigates element diffusion behavior and interfacial microstructural evolution of a pre-melted CuNi interlayer during joining. Under optimized parameters (1080 degrees C/30 min/0.1 MPa), a joint with homogeneous microstructure and high shear strength (132 MPa) is achievable. The brazing seam primarily consists of a Cu-based solid solution with minor dispersed CuNi2Ti phases. Analysis of the Cu-Ni-Ti ternary phase diagram reveals that elevating the brazing temperature above 1056 degrees C suppresses brittle Ti-Cu and Ti-Ni intermetallic compound formation. Notably, the relatively low diffusion coefficient (9.2 x 10-14 m2/s) and high activation energy (230 kJ/mol) for Ti diffusion within the CuNi interlayer inhibit excessive Ti penetration into M42 steel and subsequent brittle phase formation, thereby enabling fabrication of high-integrity brazed joints.

SiO2f/SiO2 composites offer excellent dielectric and thermal stability, but reliable integration remains difficult due to the limitations of conventional metal brazes, including CTE mismatch and electrical conductivity. This study developed a novel all-dielectric brazing material, Bi2O3-B2O3 (BB) glass, for joining SiO2f/SiO2 composite materials. The BB glass synthesized via melt-quenching exhibits an amorphous structure, a low glass transition temperature (Tg=403 °C), and an adjustable CTE (7–9 × 10–6/ °C). Wetting experiments demonstrate excellent spreading on the SiO2f/SiO2 surface, with a contact angle as low as 16° Density functional theory (DFT) analysis reveals that the formation of Bi-O-Si bonds and B-O-Si networks at the interface enhances the bonding strength. Differential charge density and density of states (DOS) results indicate that the electronic structure of BB glass improves dielectric response and reduces insertion loss in the GHz frequency band. BB glass overcomes the shortcomings of traditional brazing materials, providing a theoretical and technical foundation for reliable joining of SiO2f/SiO2 composite materials in extreme environments.

As modern electronic systems advance toward compact architectures and intensified power densities, managing heat generation and dissipation has become a central challenge affecting both device stability and functional reliability. In this study, a carbon-coated three-dimensional (3D) porous copper foam composite (CFCC) was synthesized using a combined hydrothermal and annealing process to enhance heat dissipation. Optimization studies revealed that the combination of 6 g glucose with a 600 degrees C annealing treatment produced the most favorable coating quality. Consequently, the CFCC exhibited an in-plane thermal conductivity of 16.3 W m- 1 K- 1 and a thermal diffusivity of 28.5 mm2 s-1, representing 39.3% and 122.7% increases over pristine copper foam, respectively. Infrared thermography confirmed significantly improved heat spreading, with the optimized composite maintaining the lowest steady-state temperature (145.8 degrees C) under a constant 160 degrees C heat load. Microstructural and mechanistic investigations indicate that the improved heat-transfer capability originates from the higher ordering of the carbon domains, the decrease in structural defects, and the strengthened Cu-C interfacial interactions. These factors collectively reduce phonon scattering, extend the phonon mean free path, and minimize interfacial thermal resistance, enabling effective three-dimensional heat conduction. Overall, the integrated hydrothermal-annealing strategy presents a controllable, scalable, and cost-effective approach for producing high-quality carbon coatings on porous metal substrates, offering substantial promise for advanced thermal management in next-generation high-power electronic systems.

Reliable Cu–Cu bonding at low temperatures is widely regarded as a promising approach for electronic packaging. This study proposes the in-situ growth of Cu nanoparticles (NPs) for direct low-temperature Cu–Cu bonding via oxidizing the Cu surface and then reducing, without introducing additional Cu NPs or Cu-containing reagent. A high shear strength of 67.2 MPa is obtained at 150 °C/5 min/20 MPa in air, and the strength further increases to 98.4 MPa when the bonding temperature is raised to 225 °C. In addition, after aging in air at 250 °C for 500 h, the joint prepared at 150 °C/5 min/20 MPa retains a shear strength of 51.8 MPa, indicating excellent high-temperature reliability. The in-situ synthesized Cu NPs by oxidation and reduction show a well-bonded interface with the substrate, improving the driving force for the subsequent sintering. The grain orientation, dislocations and stacking faults within the synthesized Cu NPs are also beneficial to the sintering, thereby promoting rapid densification and enabling high-strength Cu–Cu bonding under low-temperature conditions.