Brazing filler metals are widely applied,which serve as an industrial adhesive in the joining of dissimilar structures.With the continuous emergence of new structures and materials,the demand for novel brazing filler ...Brazing filler metals are widely applied,which serve as an industrial adhesive in the joining of dissimilar structures.With the continuous emergence of new structures and materials,the demand for novel brazing filler metals is ever-increasing.It is of great significance to investigate the optimized composition design methods and to establish systematic design guidelines for brazing filler metals.This study elucidated the fundamental rules for the composition design of brazing filler metals from a three-dimensional perspective encompassing the basic properties of applied brazing filler metals,formability and processability,and overall cost.The basic properties of brazing filler metals refer to their mechanical properties,physicochemical properties,electromagnetic properties,corrosion resistance,and the wettability and fluidity during brazing.The formability and processability of brazing filler metals include the processes of smelting and casting,extrusion,rolling,drawing and ring-making,as well as the processes of granulation,powder production,and the molding of amorphous and microcrystalline structures.The cost of brazing filler metals corresponds to the sum of materials value and manufacturing cost.Improving the comprehensive properties of brazing filler metals requires a comprehensive and systematic consideration of design indicators.Highlighting the unique characteristics of brazing filler metals should focus on relevant technical indicators.Binary or ternary eutectic structures can effectively enhance the flow spreading ability of brazing filler metals,and solid solution structures contribute to the formability.By employing the proposed design guidelines,typical Ag based,Cu based,Zn based brazing filler metals,and Sn based solders were designed and successfully applied in major scientific and engineering projects.展开更多
Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In ad...Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was established.Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond.When the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 MPa.The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.展开更多
This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential ther...This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.展开更多
A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the rel...A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature,interfacial microstructure and joint strength were emphatically investigated.Results show that the TiAl joints brazed at 1160 and 1180℃ possess three interfacial layers and mainly consist of α_(2)-Ti_(3)Al,τ_(3)-Al_(3)NiTi_(2) and Ti_(2)Ni,but the brazing seams are no longer layered and Ti_(2)Ni is completely replaced by the uniformly distributed τ_(3)-Al_(3)NiTi_(2) at 1200 and 1220℃ due to the destruction of α_(2)-Ti_(3)Al barrier layer.This transformation at 1200℃ obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa.Notably,the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.展开更多
The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high deman...The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its application.To achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution process.Microstructural evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension tests.The findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing seam.The effects of grain size,such as pinning and splitting,are amplified at higher brazing temperatures.Additionally,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture mode.The fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack path.Therefore,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.展开更多
Diamond tools have been widely used in national defense military,automobile manufacturing,resource exploitation and other fields.Laser brazing diamond technology is often applied to the preparation of diamond tools.Ho...Diamond tools have been widely used in national defense military,automobile manufacturing,resource exploitation and other fields.Laser brazing diamond technology is often applied to the preparation of diamond tools.However,the formation and expansion of cracks in the process of laser brazing diamond seriously affect the mechanical properties of diamond tools.In order to solve the crack problem of laser brazing diamond,many scholars are committed to the research on improving the solder,optimizing the laser process parameters,improving the laser brazing equipment,optimizing the design of joint form,and developing ultrasonic-assisted laser brazing technology,etc.These studies have achieved certain results.Aiming at the research status of laser brazing diamond crack problem,the crack characteristics of brazing diamond are firstly introduced,and the formation reasons of laser brazing diamond crack are elaborated.Then,the elemental characteristics of brazing filler metals used in brazing diamond are introduced.The influences of Ni-Cr and Ag-Cu-Ti alloy solder and laser process parameters on the crack problem are viewed.Finally,the solutions to the crack problem by scholars at home and abroad in recent years are summarized,and the future research directions to solve crack problem are prospected.展开更多
Brazing,an important welding and joining technology,can achieve precision joining of materials in advanced manufacturing.And the first principle calculation is a new material simulation method in high-throughput compu...Brazing,an important welding and joining technology,can achieve precision joining of materials in advanced manufacturing.And the first principle calculation is a new material simulation method in high-throughput computing.It can calculate the interfacial structure,band structure,electronic structure,and other properties between dissimilar materials,predicting various properties.It plays an important role in assisting practical research and guiding experimental designs by predicting material properties.It can largely improve the quality of welded components and joining efficiency.The relevant theoretical foundation is reviewed,including the first principle and density functional theory.Exchange-correlation functional and pseudopotential plane wave approach was also introduced.Then,the latest research progress of the first principle in brazing was also summarized.The application of first principle calculation mainly includes formation energy,adsorption energy,surface energy,adhesion work,interfacial energy,interfacial contact angle,charge density differences,density of states,and mulliken population.The energy,mechanical,and electronic properties were discussed.Finally,the limitations and shortcomings of the research in the first principle calculation of brazed interface were pointed out.Future developmental directions were presented to provide reference and theoretical basis for realizing high-throughput calculations of brazed joint interfaces.展开更多
The contact-reactive brazing of Al_(0.3)CoCrFeNi high-entropy alloys with a Nb interlayer was researched.The effects of Nb thickness and brazing temperature on the interfacial microstructure and mechanical properties ...The contact-reactive brazing of Al_(0.3)CoCrFeNi high-entropy alloys with a Nb interlayer was researched.The effects of Nb thickness and brazing temperature on the interfacial microstructure and mechanical properties of Al_(0.3)CoCrFeNi joints were investigated.The results show that with Nb thickness increasing from 10 to 100μm,the average width of Al_(0.3)CoCrFeNi joints is increased from 127 to 492μm and the erosion volume of Al_(0.3)CoCrFeNi base metals(BMs)by face-centered cubic-Nb eutectic liquid is enlarged accordingly.With increasing brazing temperature from 1280 to 1360℃,the intergranular penetration of eutectic liquid into Al_(0.3)CoCrFeNi BMs becomes more severe and lamellar Laves phase is broken-up and spherized.The shear strength of joint is increased gradually from 374 to 486 MPa and then decreased to 475 MPa.The maximum shear strength value of 486 MPa is obtained when brazing at 1340℃ for 10 min,reaching about 78% of the shear strength of Al_(0.3)CoCrFeNi BMs.Besides,the brazing mechanism was analyzed in details.展开更多
Reactive brazing of TiAl-based intermetallics and Ni-based alloy with Ti foil as interlayer was investigated. The interfacial microstructure and shear strength of the joints were studied. According to the experimental...Reactive brazing of TiAl-based intermetallics and Ni-based alloy with Ti foil as interlayer was investigated. The interfacial microstructure and shear strength of the joints were studied. According to the experimental observations, the molten interlayer reacts vigorously with base metals, forming several continuous reaction layers. The typical interfacial microstructure of the joint can be expressed as GH99/（Ni,Cr）ss（γ）/TiNi（β2）＋TiNi2Al（τ4）＋Ti2Ni（δ）/δ＋Ti3Al（α2）＋Al3NiTi2（τ3）/α2＋τ3/TiAl. The maximum shear strength is 258 MPa for the specimen brazed at 1000°C for 10 min. Higher brazing temperature or longer brazing time causes coarsening of the phases in the brazing seam and formation of brittle intermetallic layer, which greatly depresses the shear strength of the joints.展开更多
A novel joining method,double-stage diffusion-brazing of an AZ31 magnesium alloy and a 304L austenitic stainless steel,was carried out using a pure copper interlayer.The solid-state diffusion bonding of 304L to copper...A novel joining method,double-stage diffusion-brazing of an AZ31 magnesium alloy and a 304L austenitic stainless steel,was carried out using a pure copper interlayer.The solid-state diffusion bonding of 304L to copper was conducted at 850 ℃ for 20 min followed by brazing to AZ31 at 520 ℃ and 495 ℃ for various time.Microstructural characteristics of the diffusion-brazed joints were investigated in detail.A defect free interface of Fe-Cu diffusion area appeared between the Cu alloy and the 304L steel.Cu-Mg reaction products were formed between AZ31 and Cu alloys.A layered structure including AZ31/Cu-Mg compounds/Cu/Fe-Cu diffusion layer/304L was present in the joint.With time prolonging,the reduction in the width of Cu layer was balanced by the increase in the width of Cu-Mg compounds zone.Microhardness peaks in the zone between AZ31 and Cu layer were attributed to the formation of Mg-Cu compounds in this zone.展开更多
Contact reactive brazing of 6063 Al alloy and 1Cr18Ni9Ti stainless steel was researched by using Cu as interlayer. Effect of brazing time on microstructure of the joints, as well as the dissolution behaviors of Cu int...Contact reactive brazing of 6063 Al alloy and 1Cr18Ni9Ti stainless steel was researched by using Cu as interlayer. Effect of brazing time on microstructure of the joints, as well as the dissolution behaviors of Cu interlayer was analyzed. The results show that the product of reaction zone near 1Cr18Ni9Ti is composed of Fe2Al5, FeAl3 intermetallic compound （IMC）, and Cu-Al IMC; the near by area is composed of Al-Cu eutectic structure with Al （Cu） solid solution. With increasing the brazing time, the thickness of IMC layer at the interface increases, while the width of Al-Cu eutectic structure with Al（Cu） solution decreases. Calculation shows the dissolution rate of Cu interlayer is very fast. The complete dissolution time is about 0.47 s for Cu interlayer with 10 μm in thickness used in this study.展开更多
The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray spectroscopy （EDS...The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction（XRD）. The effects of brazing atmospheres on the as-brazed NiCr brazing alloy composite structures and interracial microstructure are studied between diamond grits and brazing alloy. Results show that： （1） There are different composite structures of as-brazed NiCr brazing alloy under different oxygen partial pressures in vacuum and argon gas. B203 exists on the surface of the brazed samples under argon gas furnace brazing. It indicates that oxygen plays an important role in the resultants of as-brazed NiCr brazing alloy during the brazing process. （2） There are different interfacial microstructures in different brazing atmospheres, but the main reaction product is chromium carbides. The chromium carbides in argon gas furnace brazing grow in a disordered form, but those in vacuum furnace brazing grow radiated. And the scale of grains in argon gas is smaller than those in vacuum.展开更多
A series of Al?Si?Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al?Si?G...A series of Al?Si?Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al?Si?Ge filler metals drops from 592 to 519 °C as the content of Ge increases from 0 to 30% (mass fraction). As the content of Ge increases, bright eutectic Ge forms. However, as the Ge content exceeds 20%, the aggregation growth of the eutectic structure tends to happen and coarsened primary Si?Ge particle forms, which is detrimental to the properties of alloys. The Al?10.8Si?10Ge filler metal has good processability and wettability with the base metal Al. When this filler metal is used to braze 1060 aluminum, the complete joint can be achieved. Furthermore, the shear strength test results show that the fracture of brazed joint with Al?10.8Si?10Ge filler metal occurs in the base metal.展开更多
To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy(Cantor alloys,HEA)caused by the violent atomic interdiffusion,the higher configuration entropy on Cantor alloys surface was desi...To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy(Cantor alloys,HEA)caused by the violent atomic interdiffusion,the higher configuration entropy on Cantor alloys surface was designed and realized via eutectic high-entropy(EHEA)transformation.Meanwhile,to effectively alleviate the residual stress caused by the notable difference in the thermal expansion coefficient(CTE)between Cantor alloys and Zr-3 alloys,a cladding layer was applied to the HEA surface using laser cladding technology of Nb,followed by brazing to Zr-3 alloys with Zr63.2Cu filler.The cladding layer’s microstructure comprised Nbss and FCC+(Co,Ni)_(2) Nb eutectic structure,resulting from an in-situ reaction between Cantor alloys and Nb.The Nbss and FCC demonstrated good plasticity,and the(Co,Ni)_(2) Nb Laves phase provided increased strength,endowing both good plastic deformation ability and strength of the cladding layer.Notably,the existence of EHEA in the laser cladding layer made the Cantor alloy entropy from 1.61 R to 1.77 R,greatly enhancing its thermal stability and suppressing the grave grain boundary infiltration.Joints produced via laser cladding with Nb-assisted brazing exhibited a complex microstructure(HEA/Nbss+FCC+(Co,Ni)_(2)Nb/(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/(Zr,Nb)_(2)(Cu,Ni,Co,Fe)+(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/Zr-3) and a significantly improved shear strength of 242.8 MPa at 1010℃ for 10 min,42.4%higher than that of directly brazed joints.This improvement was attributed to reduced grain boundary infiltration,alleviated residual stress due to CTE disparity,and eliminated micro-cracks in the brazing seam.This study presents an effective solution for reducing residual stresses and achieving reliable bonding between Cantor alloys and Zr-3 alloys,with potential applications in brazing CoCrFeNi-based HEA and Zr-3 due to the beneficial eutectic reaction between CoCrFeNi and Nb.展开更多
Polycrystalline diamond compact(PDC)cutters and carbon steel were brazed by AgCuInTi filler metal under vacuum condition.The effects of brazing temperature on the wettability of base metal and shear strength of joints...Polycrystalline diamond compact(PDC)cutters and carbon steel were brazed by AgCuInTi filler metal under vacuum condition.The effects of brazing temperature on the wettability of base metal and shear strength of joints were investigated.Besides,the joint's interface microstructure,composition,and phases were analyzed.Results show that the AgCuInTi filler metal exerts a good wetting effect to the surface of cemented carbide and steel.With the increase in brazing temperature,the wetting angle decreases and the spreading area increases.The suitable temperature for vacuum brazing of PDC cutters is 770℃,and the maximum shear strength is 228 MPa at this temperature.展开更多
As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has...As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has been widely utilized for ceramic-metal heterogeneous joints.However,the residual stress relief in these welding joints is complicated and necessary.Because metals and ceramics have different properties,especially their coefficients of thermal expansion.Welding joints exhibit large residual stresses during the cooling process.The relatively high residual stresses may significantly degrade the joint properties.For this issue,four alleviation routes were reviewed:optimization of process parameters,setting an intermediate layer,surface structure modulation and particle-reinforced composite solder.The states and distribution patterns of residual stress in ceramic-metal brazed joints were summarized,and the generation and detection of residual stress were introduced.Eventually,upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures were pointed out.展开更多
Brazing has a wide acceptance in industries and its simplicity in variety of application attracts more and more patronage. The strength of brazing joint determines the reliability of brazed engineering components. So ...Brazing has a wide acceptance in industries and its simplicity in variety of application attracts more and more patronage. The strength of brazing joint determines the reliability of brazed engineering components. So the need to ascertain the reliability or to predict its failure （without some destructive testing） becomes high even with a computer aided analysis using the Finite Element Analysis. Here, we have employed the services of FEA software, Abaqus CAE, as a tool for the computer calculation to investigate a joint case of cemented carbide brazed with silver-based filler metal. In this paper, 2D analysis has been adopted because the thickness of the material （in 2D） does not influence the final calculation results. We have applied constant loading and constant boundary condition to explore data from the elastic and plastic strain analysis through which we were able to predict the maximum joint strength with respect to the joint thickness. The pattern of the meshing was also significant. And the result could be transferable to a real-life field situation. The final results showed that there is an optimum thickness of the filler metal with the maximum strength which matches that obtained from experiment.展开更多
The investigation evaluated the thermal shock resistance and failure mechanisms of three brazed joints when exposed to 780°C.During exposure,oxidation of the SiC_(f)/SiC composite leads to the formation of SiO_(2...The investigation evaluated the thermal shock resistance and failure mechanisms of three brazed joints when exposed to 780°C.During exposure,oxidation of the SiC_(f)/SiC composite leads to the formation of SiO_(2).Residual oxygen will penetrate the high-entropy alloy while retaining its Face-Centered Cubic(FCC)structure.Additionally,the FCC Cr_(23)C_(6)phase adjacent to the composite reacted with SiC,producing hexagonal Cr_(2)C,compromising the ability of joint to withstand plastic deformation.Moreover,the presence of Nb(s,s)and significant MoNiSi phases induced a gradual alteration in the Coefficient of Thermal Expansion(CTE),facilitating the initiation of shear fractures from the composites towards the central region of the seam,significantly affecting the overall structural integrity and failure behavior of the joint under thermal shock conditions.With an increase in the number of thermal shocks,the shear strength of joint gradually decreases,reaching a maximum of 22.36 MPa after 30 thermal shocks,surpassing that of some joints using glass fillers.展开更多
6061 aluminum alloy was successfully vacuum brazed to 304 stainless steel using Al-Si-Ge/Cu composite filler metal.The thermodynamic model was established to analyze the formation mechanism of microstructure in brazed...6061 aluminum alloy was successfully vacuum brazed to 304 stainless steel using Al-Si-Ge/Cu composite filler metal.The thermodynamic model was established to analyze the formation mechanism of microstructure in brazed joint and element diffusion behavior between filler metal and substrate.The findings indicated that the microstructure of 6061 aluminum alloy/304 stainless steel joint was a multilayer structure composed of three zones(ZoneⅠ,ZoneⅡand ZoneⅢ).The free energy(△G)calculation results indicated that Al-Si-M(M was Fe,Cr,Ni and Cu)ternary intermetallic compounds(IMCs)formed,when on M-Al side and M-Si/Ge side was similar.And only Al-M binary IMCs would be generated when there was large difference between on M-Al side and that on M-Si/Ge side.The calculation results of chemical potential of Si△_(μSi)and Ge△_(μGe)indicated that there was continuous Si and Ge diffusion toward Zone I,forming(Ge,Si)layer.The segregation of Si and Ge hindered the diffusion of Cr toward Zone II and promoted its diffusion toward(Ge,Si)layer,leading to an upward trend of Cr distribution in Al7(Fe,Cr)2Si layer.Negative△_(μNi)and△_(μFe)were responsible for continuous diffusion of Fe and Ni toward Zone II.The small difference between△_(μcu)in Zone I and Zone II contributed to distribution of CuAl2 in Zone II.The formation mechanism of joint could be mainly divided into four steps.展开更多
The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, sca...The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. Defect free joint was achieved using Ag- Cu-Zn-Sn filler metal. The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution. The increase of A8 content and the cooling rate both led to the increase of the needle like eutectic structure. The tensile strength decreased with the increase of Ag content. The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 MPa. All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.展开更多
基金National Natural Science Foundation of China(U22A20191)。
文摘Brazing filler metals are widely applied,which serve as an industrial adhesive in the joining of dissimilar structures.With the continuous emergence of new structures and materials,the demand for novel brazing filler metals is ever-increasing.It is of great significance to investigate the optimized composition design methods and to establish systematic design guidelines for brazing filler metals.This study elucidated the fundamental rules for the composition design of brazing filler metals from a three-dimensional perspective encompassing the basic properties of applied brazing filler metals,formability and processability,and overall cost.The basic properties of brazing filler metals refer to their mechanical properties,physicochemical properties,electromagnetic properties,corrosion resistance,and the wettability and fluidity during brazing.The formability and processability of brazing filler metals include the processes of smelting and casting,extrusion,rolling,drawing and ring-making,as well as the processes of granulation,powder production,and the molding of amorphous and microcrystalline structures.The cost of brazing filler metals corresponds to the sum of materials value and manufacturing cost.Improving the comprehensive properties of brazing filler metals requires a comprehensive and systematic consideration of design indicators.Highlighting the unique characteristics of brazing filler metals should focus on relevant technical indicators.Binary or ternary eutectic structures can effectively enhance the flow spreading ability of brazing filler metals,and solid solution structures contribute to the formability.By employing the proposed design guidelines,typical Ag based,Cu based,Zn based brazing filler metals,and Sn based solders were designed and successfully applied in major scientific and engineering projects.
基金National MCF Energy R&D Program(2019YFE03100400)。
文摘Ag-Cu-In-Ti low-temperature filler was used to braze the diamond and copper,and the effects of brazing temperature and soaking time on the microstructure and mechanical properties of the joints were investigated.In addition,the joint formation mechanism was discussed,and the correlation between joint microstructure and mechanical performance was established.Results show that adding appropriate amount of In into the filler can significantly reduce the filler melting point and enhance the wettability of filler on diamond.When the brazing temperature is 750°C and the soaking time is 10 min,a uniformly dense braze seam with excellent metallurgical bonding can be obtained,and its average joint shear strength reaches 322 MPa.The lower brazing temperature can mitigate the risk of diamond graphitization and also reduce the residual stresses during joining.
基金the support from Jinhua Sanhuan Welding Materials Company LimitedSchool of Materials Science and Engineering,Nanjing University of Science and Technology.
文摘This article studies the effects of different Sn contents on the melting characteristics,microstructure,and mechanical properties of brazed joints of low-silver BAg5CuZn-0.3 wt.%La brazing material.A differential thermal analyzer(HCR-1)was used to measure the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La-xSn brazing material.The results show that the addition of Sn element effect-ively reduces the solid-liquidus temperature of BAg5CuZn-0.3 wt.%La brazing material.Microstructural characterization was con-ducted using scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),X-ray diffraction(XRD),etc.Analysis re-veals that progressive aggregation and precipitation of Cu-Sn intermetallic compounds occur with increasing Sn content,leading to microstructural coarsening.Notably,severe grain coarsening is observed when the Sn content reaches 4 wt.%.Shear testing of the BAg5CuZn-0.3 wt.%La-xSn brazing joints reveals a non-monotonic trend in joint strength:as Sn content increases,the shear strength initially improves but subsequently deteriorates after reaching an optimal value.
基金the National Natural Science Foundation of China(No.51865012)the Natural Science Foundation of Jiangxi Province,China(No.20202BABL204040)+3 种基金the Open Foundation of National Engineering Research Center of Near-net-shape Forming for Metallic Materials,China(No.2016005)the Science Foundation of Educational Department of Jiangxi Province,China(No.GJJ170372)the GF Basic Scientific Research Project,China(No.JCKY2020205C002)the Civil Population Supporting Planning and Development Project,China(No.JPPT125GH038).
文摘A novel micro-nano Ti−10Cu−10Ni−8Al−8Nb−4Zr−1.5Hf filler was used to vacuum braze Ti−47Al−2Nb−2Cr−0.15B alloy at 1160−1220℃ for 30 min.The interfacial microstructure and formation mechanism of TiAl joints and the relationships among brazing temperature,interfacial microstructure and joint strength were emphatically investigated.Results show that the TiAl joints brazed at 1160 and 1180℃ possess three interfacial layers and mainly consist of α_(2)-Ti_(3)Al,τ_(3)-Al_(3)NiTi_(2) and Ti_(2)Ni,but the brazing seams are no longer layered and Ti_(2)Ni is completely replaced by the uniformly distributed τ_(3)-Al_(3)NiTi_(2) at 1200 and 1220℃ due to the destruction of α_(2)-Ti_(3)Al barrier layer.This transformation at 1200℃ obviously improves the tensile strength of the joint and obtains a maximum of 343 MPa.Notably,the outward diffusion of Al atoms from the dissolution of TiAl substrate dominates the microstructure evolution and tensile strength of the TiAl joint at different brazing temperatures.
基金co-supported by the National Natural Science Foundation of China(No.52105316)the National Natural Foundation of Jiangxi,China(No.2021BAB214046)+1 种基金the Fundamental Research Funds for the Central Universities,China(No.501LKQB2022107021)Young Elite Scientists Sponsorship Program by the China Association for Science and Technology(No.YESS20200397)。
文摘The systematic investigation of the mechanical properties and microstructure evolution process of ultra-thin-walled Inconel 718 capillary brazing joints is of great significance because of the exceptionally high demands on its application.To achieve this objective,this study investigates the impact of three distinct brazing temperatures and five typical grain sizes on the brazed joints’mechanical properties and microstructure evolution process.Microstructural evolution analysis was conducted based on Electron Back Scatter Diffraction(EBSD),Scanning Electron Microscopy(SEM),X-Ray Diffraction(XRD),High-Resolution Transmission Electron Microscopy(HRTEM),and Focused Ion Beam(FIB).Besides,the mechanical properties and fracture behavior were studied based on the uniaxial tension tests and in-situ tension tests.The findings reveal that the brazing joint’s strength is higher for the fine-grain capillary than the coarse-grain one,primarily due to the formation of a dense branch structure composed of G-phase in the brazing seam.The effects of grain size,such as pinning and splitting,are amplified at higher brazing temperatures.Additionally,micro-cracks initiate around brittle intermetallic compounds and propagate through the eutectic zone,leading to a cleavage fracture mode.The fracture stress of fine-grain specimens is higher than that of coarse-grain due to the complex micro-crack path.Therefore,this study contributes significantly to the literature by highlighting the crucial impact of grain size on the brazing properties of ultra-thin-walled Inconel 718 structures.
基金supported by Central Plain's leading talent fund for Science,Technology and Innovation of China(Grant No.234200510015).
文摘Diamond tools have been widely used in national defense military,automobile manufacturing,resource exploitation and other fields.Laser brazing diamond technology is often applied to the preparation of diamond tools.However,the formation and expansion of cracks in the process of laser brazing diamond seriously affect the mechanical properties of diamond tools.In order to solve the crack problem of laser brazing diamond,many scholars are committed to the research on improving the solder,optimizing the laser process parameters,improving the laser brazing equipment,optimizing the design of joint form,and developing ultrasonic-assisted laser brazing technology,etc.These studies have achieved certain results.Aiming at the research status of laser brazing diamond crack problem,the crack characteristics of brazing diamond are firstly introduced,and the formation reasons of laser brazing diamond crack are elaborated.Then,the elemental characteristics of brazing filler metals used in brazing diamond are introduced.The influences of Ni-Cr and Ag-Cu-Ti alloy solder and laser process parameters on the crack problem are viewed.Finally,the solutions to the crack problem by scholars at home and abroad in recent years are summarized,and the future research directions to solve crack problem are prospected.
基金financially supported by National Natural Science Foundation of China(52475347,52071165)National Foreign Experts Program of Ministry of Science and Technology(G2023026003L)+2 种基金China Postdoctoral Fund(2023M740475)Henan Provincial Science and Technology Joint Fund(Industry)(225101610002)Program for Science&Technology Innovation Talents in Universities of Henan Province,China(22HASTIT026),International Science and Technology Cooperation Project of Henan Province(242102521057),China,the Program for the Top Young Talents of Henan Province,China and Frontier Exploration Project of Longmen Laboratory(LMQYTSKT016),China.
文摘Brazing,an important welding and joining technology,can achieve precision joining of materials in advanced manufacturing.And the first principle calculation is a new material simulation method in high-throughput computing.It can calculate the interfacial structure,band structure,electronic structure,and other properties between dissimilar materials,predicting various properties.It plays an important role in assisting practical research and guiding experimental designs by predicting material properties.It can largely improve the quality of welded components and joining efficiency.The relevant theoretical foundation is reviewed,including the first principle and density functional theory.Exchange-correlation functional and pseudopotential plane wave approach was also introduced.Then,the latest research progress of the first principle in brazing was also summarized.The application of first principle calculation mainly includes formation energy,adsorption energy,surface energy,adhesion work,interfacial energy,interfacial contact angle,charge density differences,density of states,and mulliken population.The energy,mechanical,and electronic properties were discussed.Finally,the limitations and shortcomings of the research in the first principle calculation of brazed interface were pointed out.Future developmental directions were presented to provide reference and theoretical basis for realizing high-throughput calculations of brazed joint interfaces.
基金the Outstanding Youth Innovation Team in Universities of Shandong Province(2023KJ114)National Natural Science Foundation of China(Grant No.52305344)Natural Science Foundation of Shandong Province,China(Grant No.ZR2022QE073).
文摘The contact-reactive brazing of Al_(0.3)CoCrFeNi high-entropy alloys with a Nb interlayer was researched.The effects of Nb thickness and brazing temperature on the interfacial microstructure and mechanical properties of Al_(0.3)CoCrFeNi joints were investigated.The results show that with Nb thickness increasing from 10 to 100μm,the average width of Al_(0.3)CoCrFeNi joints is increased from 127 to 492μm and the erosion volume of Al_(0.3)CoCrFeNi base metals(BMs)by face-centered cubic-Nb eutectic liquid is enlarged accordingly.With increasing brazing temperature from 1280 to 1360℃,the intergranular penetration of eutectic liquid into Al_(0.3)CoCrFeNi BMs becomes more severe and lamellar Laves phase is broken-up and spherized.The shear strength of joint is increased gradually from 374 to 486 MPa and then decreased to 475 MPa.The maximum shear strength value of 486 MPa is obtained when brazing at 1340℃ for 10 min,reaching about 78% of the shear strength of Al_(0.3)CoCrFeNi BMs.Besides,the brazing mechanism was analyzed in details.
基金Projects (50975062, 51105107, 51021002) supported by the National Natural Science Foundation of ChinaProjects (QC2011C044) supported by the Natural Science Foundation of Heilongjiang Province,China+1 种基金Project (20112302130005) supported by the Specialized Research Fund for the Doctoral Program of Higher Education,ChinaProject (CUGA4130902510) supported by the China Postdoctoral Science Foundation Funded
文摘Reactive brazing of TiAl-based intermetallics and Ni-based alloy with Ti foil as interlayer was investigated. The interfacial microstructure and shear strength of the joints were studied. According to the experimental observations, the molten interlayer reacts vigorously with base metals, forming several continuous reaction layers. The typical interfacial microstructure of the joint can be expressed as GH99/（Ni,Cr）ss（γ）/TiNi（β2）＋TiNi2Al（τ4）＋Ti2Ni（δ）/δ＋Ti3Al（α2）＋Al3NiTi2（τ3）/α2＋τ3/TiAl. The maximum shear strength is 258 MPa for the specimen brazed at 1000°C for 10 min. Higher brazing temperature or longer brazing time causes coarsening of the phases in the brazing seam and formation of brittle intermetallic layer, which greatly depresses the shear strength of the joints.
基金Project(51205428) supported by the National Natural Science Foundation of ChinaProject(CDJRC10130011) supported by the Fundamental Research Funds for the Central Universities,China
文摘A novel joining method,double-stage diffusion-brazing of an AZ31 magnesium alloy and a 304L austenitic stainless steel,was carried out using a pure copper interlayer.The solid-state diffusion bonding of 304L to copper was conducted at 850 ℃ for 20 min followed by brazing to AZ31 at 520 ℃ and 495 ℃ for various time.Microstructural characteristics of the diffusion-brazed joints were investigated in detail.A defect free interface of Fe-Cu diffusion area appeared between the Cu alloy and the 304L steel.Cu-Mg reaction products were formed between AZ31 and Cu alloys.A layered structure including AZ31/Cu-Mg compounds/Cu/Fe-Cu diffusion layer/304L was present in the joint.With time prolonging,the reduction in the width of Cu layer was balanced by the increase in the width of Cu-Mg compounds zone.Microhardness peaks in the zone between AZ31 and Cu layer were attributed to the formation of Mg-Cu compounds in this zone.
文摘Contact reactive brazing of 6063 Al alloy and 1Cr18Ni9Ti stainless steel was researched by using Cu as interlayer. Effect of brazing time on microstructure of the joints, as well as the dissolution behaviors of Cu interlayer was analyzed. The results show that the product of reaction zone near 1Cr18Ni9Ti is composed of Fe2Al5, FeAl3 intermetallic compound （IMC）, and Cu-Al IMC; the near by area is composed of Al-Cu eutectic structure with Al （Cu） solid solution. With increasing the brazing time, the thickness of IMC layer at the interface increases, while the width of Al-Cu eutectic structure with Al（Cu） solution decreases. Calculation shows the dissolution rate of Cu interlayer is very fast. The complete dissolution time is about 0.47 s for Cu interlayer with 10 μm in thickness used in this study.
基金Supported by the National Natural Science Foundation of China(50475040)the Aeronautical Science Foundation of China(2005ZH52060)the Natural Science Foundation of Jiangsu Province(BK2006723)~~
文摘The samples of brazed diamond grits with NiCr brazing alloy are prepared in vacuum and argon gas. The microstructures are analyzed with scanning electron microscope （SEM）, energy dispersive X-ray spectroscopy （EDS） and X-ray diffraction（XRD）. The effects of brazing atmospheres on the as-brazed NiCr brazing alloy composite structures and interracial microstructure are studied between diamond grits and brazing alloy. Results show that： （1） There are different composite structures of as-brazed NiCr brazing alloy under different oxygen partial pressures in vacuum and argon gas. B203 exists on the surface of the brazed samples under argon gas furnace brazing. It indicates that oxygen plays an important role in the resultants of as-brazed NiCr brazing alloy during the brazing process. （2） There are different interfacial microstructures in different brazing atmospheres, but the main reaction product is chromium carbides. The chromium carbides in argon gas furnace brazing grow in a disordered form, but those in vacuum furnace brazing grow radiated. And the scale of grains in argon gas is smaller than those in vacuum.
基金Project(2010A080402014)supported by the Guangdong Provincial Science and Technology Foundation,China
文摘A series of Al?Si?Ge filler metals were studied for brazing aluminum. The microstructures and properties of the filler metals were investigated systematically. The results show that the liquidus temperature of Al?Si?Ge filler metals drops from 592 to 519 °C as the content of Ge increases from 0 to 30% (mass fraction). As the content of Ge increases, bright eutectic Ge forms. However, as the Ge content exceeds 20%, the aggregation growth of the eutectic structure tends to happen and coarsened primary Si?Ge particle forms, which is detrimental to the properties of alloys. The Al?10.8Si?10Ge filler metal has good processability and wettability with the base metal Al. When this filler metal is used to braze 1060 aluminum, the complete joint can be achieved. Furthermore, the shear strength test results show that the fracture of brazed joint with Al?10.8Si?10Ge filler metal occurs in the base metal.
基金supported by the National Natural Science Foundation of China(Grant Nos.52275321 and 52205348)the Shandong Natural Science Foundation(Grant No.ZR2023JQ021)+3 种基金the Taishan Scholars Foundation of Shandong Province(No.tsqn 201812128)the Innovation Scientists and Technicians Troop Projects of Henan Province(No.204200510031)the Heilongjiang Touyan Innovation Team Program(No.HITTY-20190013)supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)(Nos.NRF-2021R1A2C3006662 and NRF-2022R1A5A1030054).
文摘To effectively regulate the grain boundary infiltration in CoCrFeMnNi high-entropy alloy(Cantor alloys,HEA)caused by the violent atomic interdiffusion,the higher configuration entropy on Cantor alloys surface was designed and realized via eutectic high-entropy(EHEA)transformation.Meanwhile,to effectively alleviate the residual stress caused by the notable difference in the thermal expansion coefficient(CTE)between Cantor alloys and Zr-3 alloys,a cladding layer was applied to the HEA surface using laser cladding technology of Nb,followed by brazing to Zr-3 alloys with Zr63.2Cu filler.The cladding layer’s microstructure comprised Nbss and FCC+(Co,Ni)_(2) Nb eutectic structure,resulting from an in-situ reaction between Cantor alloys and Nb.The Nbss and FCC demonstrated good plasticity,and the(Co,Ni)_(2) Nb Laves phase provided increased strength,endowing both good plastic deformation ability and strength of the cladding layer.Notably,the existence of EHEA in the laser cladding layer made the Cantor alloy entropy from 1.61 R to 1.77 R,greatly enhancing its thermal stability and suppressing the grave grain boundary infiltration.Joints produced via laser cladding with Nb-assisted brazing exhibited a complex microstructure(HEA/Nbss+FCC+(Co,Ni)_(2)Nb/(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/(Zr,Nb)_(2)(Cu,Ni,Co,Fe)+(Zr,Nb)(Cr,Mn)_(2)+(Zr,Nb)ss/Zr-3) and a significantly improved shear strength of 242.8 MPa at 1010℃ for 10 min,42.4%higher than that of directly brazed joints.This improvement was attributed to reduced grain boundary infiltration,alleviated residual stress due to CTE disparity,and eliminated micro-cracks in the brazing seam.This study presents an effective solution for reducing residual stresses and achieving reliable bonding between Cantor alloys and Zr-3 alloys,with potential applications in brazing CoCrFeNi-based HEA and Zr-3 due to the beneficial eutectic reaction between CoCrFeNi and Nb.
基金National Natural Science Foundation of China(52075551,52271045,51975469)Supported by State Key Laboratory of Advanced Welding and Joining(AWJ-22M09)+2 种基金Supported by State Key Laboratory of Advanced Brazing Filler Metals and Technology(SKLABFMT201904)Key Research and Development Program of Shaanxi Province(2022GY-224)Innovative Talent Recommendation Program(Youth Science and Technology New Star Project)of Shaanxi Province(2020 KJX X-045)。
文摘Polycrystalline diamond compact(PDC)cutters and carbon steel were brazed by AgCuInTi filler metal under vacuum condition.The effects of brazing temperature on the wettability of base metal and shear strength of joints were investigated.Besides,the joint's interface microstructure,composition,and phases were analyzed.Results show that the AgCuInTi filler metal exerts a good wetting effect to the surface of cemented carbide and steel.With the increase in brazing temperature,the wetting angle decreases and the spreading area increases.The suitable temperature for vacuum brazing of PDC cutters is 770℃,and the maximum shear strength is 228 MPa at this temperature.
基金National Program of Foreign Experts of China(G2023026003L)National Natural Science Foundation of China(52475347)+4 种基金Postdoctoral Fund(2023M740475)International Science and Technology Cooperation Project of Henan Province(242102521057)Frontier Exploration Projects of Longmen Laboratory(LMQYTSKT016)Central Plains Science and Technology Innovation Leading TalentsProvincial Science and Technology R&D Program Joint Fund Projects(235200810030)。
文摘As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has been widely utilized for ceramic-metal heterogeneous joints.However,the residual stress relief in these welding joints is complicated and necessary.Because metals and ceramics have different properties,especially their coefficients of thermal expansion.Welding joints exhibit large residual stresses during the cooling process.The relatively high residual stresses may significantly degrade the joint properties.For this issue,four alleviation routes were reviewed:optimization of process parameters,setting an intermediate layer,surface structure modulation and particle-reinforced composite solder.The states and distribution patterns of residual stress in ceramic-metal brazed joints were summarized,and the generation and detection of residual stress were introduced.Eventually,upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures were pointed out.
文摘Brazing has a wide acceptance in industries and its simplicity in variety of application attracts more and more patronage. The strength of brazing joint determines the reliability of brazed engineering components. So the need to ascertain the reliability or to predict its failure （without some destructive testing） becomes high even with a computer aided analysis using the Finite Element Analysis. Here, we have employed the services of FEA software, Abaqus CAE, as a tool for the computer calculation to investigate a joint case of cemented carbide brazed with silver-based filler metal. In this paper, 2D analysis has been adopted because the thickness of the material （in 2D） does not influence the final calculation results. We have applied constant loading and constant boundary condition to explore data from the elastic and plastic strain analysis through which we were able to predict the maximum joint strength with respect to the joint thickness. The pattern of the meshing was also significant. And the result could be transferable to a real-life field situation. The final results showed that there is an optimum thickness of the filler metal with the maximum strength which matches that obtained from experiment.
基金the financial support from the National Natural Science Foundation of China(No.52374402)the National Key Research and Development Program,China(No.2022YFB3402200)+2 种基金the National Science and Technology Major Project,China(No.J2022-VII-00030045)the Project of Key Areas of Innovation Team in Shaanxi Province,China(No.2024RS-CXTD-20)the Innovation Foundation for Doctor Dissertation of Northwestern Polytechnical University,China(No.CX2024055)。
文摘The investigation evaluated the thermal shock resistance and failure mechanisms of three brazed joints when exposed to 780°C.During exposure,oxidation of the SiC_(f)/SiC composite leads to the formation of SiO_(2).Residual oxygen will penetrate the high-entropy alloy while retaining its Face-Centered Cubic(FCC)structure.Additionally,the FCC Cr_(23)C_(6)phase adjacent to the composite reacted with SiC,producing hexagonal Cr_(2)C,compromising the ability of joint to withstand plastic deformation.Moreover,the presence of Nb(s,s)and significant MoNiSi phases induced a gradual alteration in the Coefficient of Thermal Expansion(CTE),facilitating the initiation of shear fractures from the composites towards the central region of the seam,significantly affecting the overall structural integrity and failure behavior of the joint under thermal shock conditions.With an increase in the number of thermal shocks,the shear strength of joint gradually decreases,reaching a maximum of 22.36 MPa after 30 thermal shocks,surpassing that of some joints using glass fillers.
基金supported by National Natural Science Foundation of China(Grant No.203S20230001),awarded to Wei-min Long。
文摘6061 aluminum alloy was successfully vacuum brazed to 304 stainless steel using Al-Si-Ge/Cu composite filler metal.The thermodynamic model was established to analyze the formation mechanism of microstructure in brazed joint and element diffusion behavior between filler metal and substrate.The findings indicated that the microstructure of 6061 aluminum alloy/304 stainless steel joint was a multilayer structure composed of three zones(ZoneⅠ,ZoneⅡand ZoneⅢ).The free energy(△G)calculation results indicated that Al-Si-M(M was Fe,Cr,Ni and Cu)ternary intermetallic compounds(IMCs)formed,when on M-Al side and M-Si/Ge side was similar.And only Al-M binary IMCs would be generated when there was large difference between on M-Al side and that on M-Si/Ge side.The calculation results of chemical potential of Si△_(μSi)and Ge△_(μGe)indicated that there was continuous Si and Ge diffusion toward Zone I,forming(Ge,Si)layer.The segregation of Si and Ge hindered the diffusion of Cr toward Zone II and promoted its diffusion toward(Ge,Si)layer,leading to an upward trend of Cr distribution in Al7(Fe,Cr)2Si layer.Negative△_(μNi)and△_(μFe)were responsible for continuous diffusion of Fe and Ni toward Zone II.The small difference between△_(μcu)in Zone I and Zone II contributed to distribution of CuAl2 in Zone II.The formation mechanism of joint could be mainly divided into four steps.
基金supported by the National Natural Science Foundation of China (No. 50805038)Program for New Century Excellent Talents in University
文摘The induction brazing of brass to steel using Ag-Cu-Zn-Sn filler metal was investigated in this study. The influence of A8 content on the microstructure and properties were analyzed by means of optical microscopy, scanning electron microscopy and electron probe microanalysis. Defect free joint was achieved using Ag- Cu-Zn-Sn filler metal. The microstructure of the joint was mainly composed of Ag-based solid solution and Cu-based solid solution. The increase of A8 content and the cooling rate both led to the increase of the needle like eutectic structure. The tensile strength decreased with the increase of Ag content. The tensile strength at room temperature using Ag25CuZnSn filler metal reached 445 MPa. All fractures using Ag-Cu-Zn-Sn filler metal presented ductile characteristic.
