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
Flux-coated brazing and soldering material is a type of material-saving and emission-reducing composite material in recent years,which is the representative product of the development of brazing and soldering technolo...Flux-coated brazing and soldering material is a type of material-saving and emission-reducing composite material in recent years,which is the representative product of the development of brazing and soldering technology,which is highly concerned by welding researchers worldwide.This work mainly reviewed the research reports on the design,preparation technology,and application of flux-coated brazing and soldering materials,put forward the shortcomings of current research,and proposed the future research directions mainly focusing on the standards,the synergistic reaction mechanism between flux and metals,the alloying,and the morphology of flux-coated brazing and soldering materials in order to provide reference information and theoretical guidance for related research and technological development in the field of welding.展开更多
Regarding the metallurgical considerations and the melting points of Ti-Mn-Fe eutectic alloy and Ni-Co-V ternary alloy,a Ti-Mn-Fe-Ni-Co-V senary system filler metal was proposed for joining TiAl-based alloy.The senary...Regarding the metallurgical considerations and the melting points of Ti-Mn-Fe eutectic alloy and Ni-Co-V ternary alloy,a Ti-Mn-Fe-Ni-Co-V senary system filler metal was proposed for joining TiAl-based alloy.The senary filler alloy consisted of TiFe,TiMn and Ti-based solid solution phases.It exhibited the liquidus temperatures of 1110.8℃and a contact angle of 37°on TiAl alloy after heating at 1110℃for 10 min.The brazed joint was composed of B2,γ-TiAl andα_(2)-Ti_(3)Al as well as residual brazing filler reaction phase.With increasing brazing temperature or prolonging dwell time,joint thickness andγ-TiAl phase volume fraction increased.The brazing condition of 1180℃/45 min gave theγ-TiAl phase content of 21.6 vol.%within the joint and the joint thickness of 270μm,and the maximum joint tensile strength reached 488 MPa at ambient temperature,with the joint strength coefficient of 82.7%.The joints offered tensile strength of 521 MPa at 700℃and 498 MPa at 800℃,corresponding to the joint strength coefficient of 85.1%and 96.3%,respectively.In this case,the joint fractured at the brazing seam with a flexural morphology,leading to the im-provement of joint strength.The typical composition within the joint was characterized by 0.47-2.09 at.%Fe,1.15-2.11 at.%Mn,0.08-0.59 at.%Ni,0.03-0.25 at.%Co and 0.15-0.35 at.%V,and these alloying elements had a positive strengthening effect on the brazed joint.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
The brazing of 55% SiCp/A356 (volume fraction) composites in air using Zn-Al alloy as a filler metal was investigated.During the brazing process,ultrasonic vibrations were applied to samples for bonding and a signific...The brazing of 55% SiCp/A356 (volume fraction) composites in air using Zn-Al alloy as a filler metal was investigated.During the brazing process,ultrasonic vibrations were applied to samples for bonding and a significant dissolution of the filler metal into the matrix alloy in the base materials occurred.As brazing temperatures were increased,the thickness of the partial melting layers in the base material increased.SiC particles in the partial melting layer of the base material were transferred into the liquid filler under ultrasonic action and a bond with homogeneously distributed reinforcements was obtained after solidification.The volume fraction of SiC particles in the bonds could be varied by changing the brazing temperature.The maximum SiC particle volume fraction of the bond material reached 37% at a brazing temperature of 500 ℃.The shear strength of the brazed bonds was improved at pressures up to 244 MPa (at 20 ℃) and increased by 133.8% (at 200 ℃) compared with the filler of the Zn-based alloy.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
The vacuum induction brazing of SiC particulate reinforced LY12 alloy matrix composite using Al-28Cu-5Si-2Mg filler metal has been carried out. The micrograph of the joint interface was observed by scanning electron m...The vacuum induction brazing of SiC particulate reinforced LY12 alloy matrix composite using Al-28Cu-5Si-2Mg filler metal has been carried out. The micrograph of the joint interface was observed by scanning electron microscopy. The joint strength was determined by shear tests. The results show that brazing temperature, holding time, SiC particle volume percentage and post heat treatment influence joint strength. SiC particles happen in the brazing seam and the distribution of SiC particles in the joint is not uniform. Particle-poor zones in the joint exist near the base metal, and particle concentrate zones exist in the center of the brazing seam. In addition, the failure of the composite is predominantly initiated by the rooting of SiC particle in the brazing seam and the micro-crack expanded along the brazing seam with low energy.展开更多
In consideration of the envelopment of γ dendrites by the Hf-rich melts at the late period of solidification of the cast Ni-base superalloys containing Hf,a heat of brazing filler alloy composed of Ni-18.6Co-4.5Cr-4....In consideration of the envelopment of γ dendrites by the Hf-rich melts at the late period of solidification of the cast Ni-base superalloys containing Hf,a heat of brazing filler alloy composed of Ni-18.6Co-4.5Cr-4.7 W-25.6Hf(wt-%)was prepared.This alloy is hypereutectic.γ phase is the leading phase in eutectic γ+Ni_5Hf and γ bars are surrounded by Ni_5Hf phase.At the section perpendicular or parallel to the γ growing direction,the eutectic morphology is cellular or laminar respectively.The content of Ni_5Hf in the alloy is 68.7v.-%. The compositions of primary and eutectic Ni_5Hf are very similar.Ni,Co and Hf are the main elements and solubility of Cr and W in Ni_5Hf is very low.This alloy is an ideal brazing filler suitable to the directional or single crystal superalloy,and the elements are beneficial to superalloys properties.This filler alloy is of low melting point and of good fluidity.After braz- ing at 1240℃,5 min+1190℃,I h in 10^(-3) Pa vacuum,the microstructure of bond is the same as that of Hf-bearing superalloy.No Si and B contamination is involved.展开更多
A two-step ultrasonic-assisted brazing method and its associated apparatus were developed to make 6063 aluminum alloys joints with Al-Si-Mg filler metal. The burst phenomenon and the effect of ultrasonic direction and...A two-step ultrasonic-assisted brazing method and its associated apparatus were developed to make 6063 aluminum alloys joints with Al-Si-Mg filler metal. The burst phenomenon and the effect of ultrasonic direction and time, as well as the welding joint geometry on the burst phenomenon were investigated. The results show that the burst phenomenon occurs in the liquid filler metal under the effects of high current density, heat, and interaction force. The burst phenomenon is eliminated when the oxide film on the edge of the cross-section of the two parent metals is removed with more than or equal to 6 s ultrasonic time. A model of formation and elimination for burst was proposed, through which the blasting phenomenon can be controlled by changing the ultrasonic time and the geometrical shape of the welded joint.展开更多
Vacuum brazing experiments of Cf/C composites were carried out using pure Al and Al-5 Ti-B as brazing fillers , and shearing strength of the joints was measured. The microstructures of the brazed joints were studied b...Vacuum brazing experiments of Cf/C composites were carried out using pure Al and Al-5 Ti-B as brazing fillers , and shearing strength of the joints was measured. The microstructures of the brazed joints were studied by means of scanning electron microscopy （SEM） and energy dispersive X-ray spectrometer. The results indicate that the brazing temperature is the important processing parameter affecting the quality of the brazed joints. Vacuum brazing of Cf/C composites can be achieved employing the pure Al and AI-S Ti-B brazing fillers at a brazing temperature of 730 ℃ or 750 ℃ , respectively. Moreover, the joints have excellent microstructures with shear strength reaching the level of practical applications.展开更多
Gas pore is a common defect in brazed joint. It lowers the brazing rate and affects the properties of joint. Experimental results show that the application of unequal-gap brazing seam effectively decreases the amount ...Gas pore is a common defect in brazed joint. It lowers the brazing rate and affects the properties of joint. Experimental results show that the application of unequal-gap brazing seam effectively decreases the amount and volume of gas pores, and increases brazing rate.This paper establishes a force model of unequal-gap brazing seam, and proposes the constitutive relationship between expulsion force and curvature. The force condition of gas bubble in geometrically different brazing seams were calculated, and the results were verified with experiments. The results show that the expulsion force of gas bubble is positively correlated to the curvature of the seam geometry. The gas bubble tends to move towards the direction with large curvature and wider gap. The directional bubble movement is obtained through varying the configuration of gas-liquid interface to meet geometric conditions. Gas bubble accelerates to expulse with arc, hyperbola and cycloid brazing seams, in which the best drainage effects of gas bubble occur for cycloid seams.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
This study investigates the influences of brazing temperature, brazing time and braz- ing clearance on microstructures and high temperature strength of Inconel superalloy. Bonding is performed in a high vacuum furnace...This study investigates the influences of brazing temperature, brazing time and braz- ing clearance on microstructures and high temperature strength of Inconel superalloy. Bonding is performed in a high vacuum furnace using BNi-2 as filler metal. Brazing temperatures employed in this study are 1080 ℃, 1110 ℃ and 1140 ℃. Holding times at the brazing temperature are 5 min, 15 min and 45 min. At the same time, the investigated brazing clearances are 30μm, 60 μm and 100 pro. Microstructure of the brazed joints is analyzed by means of metallography, scanning electron microscope （SEM）. The high temperature tensile strength and microhardness are evaluated at different brazing parameters. The results show that fracture occurs wholly within the braze metal. Deformation appears to be confined to the braze metal with the base metal, showing very little plastic deformation. Brazing time shows to play the important role in the brazing parameters. The peak of microhardness is at the centerline of braze region. Induction heating has little effect on the base materials.展开更多
It＇ s well known welding takes the leading role in development of titanium structures. However, in number of cases technological processes of brazing are more appropriate and, sometimes, being the single possible, in...It＇ s well known welding takes the leading role in development of titanium structures. However, in number of cases technological processes of brazing are more appropriate and, sometimes, being the single possible, in particular, during production of multilayer thin-wall structures. It should be noted that brazing filler metals of Ti-Cu-Ni, Ti-Zr-Cu-Ni, Zr-Ti-Ni and Cu-Zr-Ti systems in a form of plastic foils, as well as in powder form are mainly used in world practice for brazing of titanium alloys. Present work provides the results of complex investigations of brazing filler metals of Ti-Zr-Fe, Ti-Zr-Mn and Ti-Zr-Co systems using differential thermal analysis, light and scanning microscopy, X-ray microspectrum analysis. Data on melting ranges of pilot alloys were obtained, and liquidas su^Caces of given systems using simplex-lattice method were build. Brazing filler metals covering brazing temperature range of current structural titanium materials based on solid solutions as well as intermetallics were proposed. Structure, chemical inhomogeniety and strength characteristics of brazed joints were studied. It is determined that brazing of solid solution based alloys （OT4, VT6 ） using indicated brazing fiUer metals ensures strength characteristics of joints, which are not inferior to that obtained with application of known brazing filler metals even if they are received at lower brazing temperature.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Henan Province Central Guiding Local Science and Technology Development Fund Project(Z20231811002)。
文摘Flux-coated brazing and soldering material is a type of material-saving and emission-reducing composite material in recent years,which is the representative product of the development of brazing and soldering technology,which is highly concerned by welding researchers worldwide.This work mainly reviewed the research reports on the design,preparation technology,and application of flux-coated brazing and soldering materials,put forward the shortcomings of current research,and proposed the future research directions mainly focusing on the standards,the synergistic reaction mechanism between flux and metals,the alloying,and the morphology of flux-coated brazing and soldering materials in order to provide reference information and theoretical guidance for related research and technological development in the field of welding.
基金supported by the National Natural Science Foundation of China(No.51705489)the National Defense Basic Scientific Research Program of China(No.JCKY2016220C003).
文摘Regarding the metallurgical considerations and the melting points of Ti-Mn-Fe eutectic alloy and Ni-Co-V ternary alloy,a Ti-Mn-Fe-Ni-Co-V senary system filler metal was proposed for joining TiAl-based alloy.The senary filler alloy consisted of TiFe,TiMn and Ti-based solid solution phases.It exhibited the liquidus temperatures of 1110.8℃and a contact angle of 37°on TiAl alloy after heating at 1110℃for 10 min.The brazed joint was composed of B2,γ-TiAl andα_(2)-Ti_(3)Al as well as residual brazing filler reaction phase.With increasing brazing temperature or prolonging dwell time,joint thickness andγ-TiAl phase volume fraction increased.The brazing condition of 1180℃/45 min gave theγ-TiAl phase content of 21.6 vol.%within the joint and the joint thickness of 270μm,and the maximum joint tensile strength reached 488 MPa at ambient temperature,with the joint strength coefficient of 82.7%.The joints offered tensile strength of 521 MPa at 700℃and 498 MPa at 800℃,corresponding to the joint strength coefficient of 85.1%and 96.3%,respectively.In this case,the joint fractured at the brazing seam with a flexural morphology,leading to the im-provement of joint strength.The typical composition within the joint was characterized by 0.47-2.09 at.%Fe,1.15-2.11 at.%Mn,0.08-0.59 at.%Ni,0.03-0.25 at.%Co and 0.15-0.35 at.%V,and these alloying elements had a positive strengthening effect on the brazed joint.
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(50375039) supported by the National Natural Science Foundation of ChinaProject supported by the Excellence Team Program at the Harbin Institute of Technology,China
文摘The brazing of 55% SiCp/A356 (volume fraction) composites in air using Zn-Al alloy as a filler metal was investigated.During the brazing process,ultrasonic vibrations were applied to samples for bonding and a significant dissolution of the filler metal into the matrix alloy in the base materials occurred.As brazing temperatures were increased,the thickness of the partial melting layers in the base material increased.SiC particles in the partial melting layer of the base material were transferred into the liquid filler under ultrasonic action and a bond with homogeneously distributed reinforcements was obtained after solidification.The volume fraction of SiC particles in the bonds could be varied by changing the brazing temperature.The maximum SiC particle volume fraction of the bond material reached 37% at a brazing temperature of 500 ℃.The shear strength of the brazed bonds was improved at pressures up to 244 MPa (at 20 ℃) and increased by 133.8% (at 200 ℃) compared with the filler of the Zn-based alloy.
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.
文摘The vacuum induction brazing of SiC particulate reinforced LY12 alloy matrix composite using Al-28Cu-5Si-2Mg filler metal has been carried out. The micrograph of the joint interface was observed by scanning electron microscopy. The joint strength was determined by shear tests. The results show that brazing temperature, holding time, SiC particle volume percentage and post heat treatment influence joint strength. SiC particles happen in the brazing seam and the distribution of SiC particles in the joint is not uniform. Particle-poor zones in the joint exist near the base metal, and particle concentrate zones exist in the center of the brazing seam. In addition, the failure of the composite is predominantly initiated by the rooting of SiC particle in the brazing seam and the micro-crack expanded along the brazing seam with low energy.
文摘In consideration of the envelopment of γ dendrites by the Hf-rich melts at the late period of solidification of the cast Ni-base superalloys containing Hf,a heat of brazing filler alloy composed of Ni-18.6Co-4.5Cr-4.7 W-25.6Hf(wt-%)was prepared.This alloy is hypereutectic.γ phase is the leading phase in eutectic γ+Ni_5Hf and γ bars are surrounded by Ni_5Hf phase.At the section perpendicular or parallel to the γ growing direction,the eutectic morphology is cellular or laminar respectively.The content of Ni_5Hf in the alloy is 68.7v.-%. The compositions of primary and eutectic Ni_5Hf are very similar.Ni,Co and Hf are the main elements and solubility of Cr and W in Ni_5Hf is very low.This alloy is an ideal brazing filler suitable to the directional or single crystal superalloy,and the elements are beneficial to superalloys properties.This filler alloy is of low melting point and of good fluidity.After braz- ing at 1240℃,5 min+1190℃,I h in 10^(-3) Pa vacuum,the microstructure of bond is the same as that of Hf-bearing superalloy.No Si and B contamination is involved.
文摘A two-step ultrasonic-assisted brazing method and its associated apparatus were developed to make 6063 aluminum alloys joints with Al-Si-Mg filler metal. The burst phenomenon and the effect of ultrasonic direction and time, as well as the welding joint geometry on the burst phenomenon were investigated. The results show that the burst phenomenon occurs in the liquid filler metal under the effects of high current density, heat, and interaction force. The burst phenomenon is eliminated when the oxide film on the edge of the cross-section of the two parent metals is removed with more than or equal to 6 s ultrasonic time. A model of formation and elimination for burst was proposed, through which the blasting phenomenon can be controlled by changing the ultrasonic time and the geometrical shape of the welded joint.
文摘Vacuum brazing experiments of Cf/C composites were carried out using pure Al and Al-5 Ti-B as brazing fillers , and shearing strength of the joints was measured. The microstructures of the brazed joints were studied by means of scanning electron microscopy （SEM） and energy dispersive X-ray spectrometer. The results indicate that the brazing temperature is the important processing parameter affecting the quality of the brazed joints. Vacuum brazing of Cf/C composites can be achieved employing the pure Al and AI-S Ti-B brazing fillers at a brazing temperature of 730 ℃ or 750 ℃ , respectively. Moreover, the joints have excellent microstructures with shear strength reaching the level of practical applications.
基金supported by the 2020 Ningbo"3315 Talent Introduction Plan"Innovative Team (C-Class)Henan Province's Major Key Technology Demand Unveiling and Tackling Key Projects (Grant No. 191110111000)。
文摘Gas pore is a common defect in brazed joint. It lowers the brazing rate and affects the properties of joint. Experimental results show that the application of unequal-gap brazing seam effectively decreases the amount and volume of gas pores, and increases brazing rate.This paper establishes a force model of unequal-gap brazing seam, and proposes the constitutive relationship between expulsion force and curvature. The force condition of gas bubble in geometrically different brazing seams were calculated, and the results were verified with experiments. The results show that the expulsion force of gas bubble is positively correlated to the curvature of the seam geometry. The gas bubble tends to move towards the direction with large curvature and wider gap. The directional bubble movement is obtained through varying the configuration of gas-liquid interface to meet geometric conditions. Gas bubble accelerates to expulse with arc, hyperbola and cycloid brazing seams, in which the best drainage effects of gas bubble occur for cycloid seams.
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supported by the National Natural Science Foundation of China(No.50875160)Shanghai Leading Academic Discipline Project (No.J51402)Natural Science Foundation of Shanghai of China (No.10ZR1412900)
文摘This study investigates the influences of brazing temperature, brazing time and braz- ing clearance on microstructures and high temperature strength of Inconel superalloy. Bonding is performed in a high vacuum furnace using BNi-2 as filler metal. Brazing temperatures employed in this study are 1080 ℃, 1110 ℃ and 1140 ℃. Holding times at the brazing temperature are 5 min, 15 min and 45 min. At the same time, the investigated brazing clearances are 30μm, 60 μm and 100 pro. Microstructure of the brazed joints is analyzed by means of metallography, scanning electron microscope （SEM）. The high temperature tensile strength and microhardness are evaluated at different brazing parameters. The results show that fracture occurs wholly within the braze metal. Deformation appears to be confined to the braze metal with the base metal, showing very little plastic deformation. Brazing time shows to play the important role in the brazing parameters. The peak of microhardness is at the centerline of braze region. Induction heating has little effect on the base materials.
文摘It＇ s well known welding takes the leading role in development of titanium structures. However, in number of cases technological processes of brazing are more appropriate and, sometimes, being the single possible, in particular, during production of multilayer thin-wall structures. It should be noted that brazing filler metals of Ti-Cu-Ni, Ti-Zr-Cu-Ni, Zr-Ti-Ni and Cu-Zr-Ti systems in a form of plastic foils, as well as in powder form are mainly used in world practice for brazing of titanium alloys. Present work provides the results of complex investigations of brazing filler metals of Ti-Zr-Fe, Ti-Zr-Mn and Ti-Zr-Co systems using differential thermal analysis, light and scanning microscopy, X-ray microspectrum analysis. Data on melting ranges of pilot alloys were obtained, and liquidas su^Caces of given systems using simplex-lattice method were build. Brazing filler metals covering brazing temperature range of current structural titanium materials based on solid solutions as well as intermetallics were proposed. Structure, chemical inhomogeniety and strength characteristics of brazed joints were studied. It is determined that brazing of solid solution based alloys （OT4, VT6 ） using indicated brazing fiUer metals ensures strength characteristics of joints, which are not inferior to that obtained with application of known brazing filler metals even if they are received at lower brazing temperature.
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.
