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
Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature...Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. The typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/TiN ＋ Ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer ＋ diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength （73 MPa） was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-Ti brazing alloy and had reached 86% of the ceramic. The release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2Ti and Ni3Ti intermetallics played the major role in the improvement of joint strength.展开更多
Vacuum brazing was successfully used to join Ti-22Al-25Nb alloy using Ti-Ni-Nb brazing alloys prepared by arc-melting. The influence of Nb content in the Ti-Ni-Nb brazing alloys on the interfacial microstructure and m...Vacuum brazing was successfully used to join Ti-22Al-25Nb alloy using Ti-Ni-Nb brazing alloys prepared by arc-melting. The influence of Nb content in the Ti-Ni-Nb brazing alloys on the interfacial microstructure and mechanical properties of the brazed joints was investigated. The results showed that the interfacial microstructure of brazed joint consisted of B2, O, ？3, and Ti2 Ni phase, while the width of brazing seams varied at different Nb contents. The room temperature shear strength reached359 MPa when the joints were brazed with eutectic Ti40Ni40Nb20 alloy at 1180？C for 20 min, and it was321, 308 and 256 MPa at 500, 650 and 800？C, respectively. Cracks primarily initiated and propagated in ？3compounds, and partially traversed B2＋O region. Moreover, the fracture surface displayed typical ductile dimples when cracks propagated through B2＋O region, which was favorable for the mechanical properties of the brazed joint.展开更多
The brazing of TiC cermet to iron was carried out at 1223K for 5-20min using Ag-Cu-Zn filler metal. The formation phase and interface structure of the joints were investigated by electron probe microanalysis (EPMA), s...The brazing of TiC cermet to iron was carried out at 1223K for 5-20min using Ag-Cu-Zn filler metal. The formation phase and interface structure of the joints were investigated by electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the joint strength was tested by shearing method. The results showed: there occurred three new formation phases, Cu(s.s), FeNi and Ag(s.s) in TiC cermet/iron joint. The interface structure was expressed as TiC cermet/Cu(s.s)+FeNi/Ag(s.s)+a little Cu(s.s)+a little FeNi/Cu(s.s)+FeNi/iron, With brazing time increasing, there appeared highest shear strength of the joints, the value of which was up to 252.2MPa when brazing time was 10min.展开更多
An Au-Pd-Co-Ni-V brazing alloy was designed for AIN ceramic joining. Its wettability on AIN was studied with the sessile drop method. The results showed that the contact angle was decreased gradu- ally with increasing...An Au-Pd-Co-Ni-V brazing alloy was designed for AIN ceramic joining. Its wettability on AIN was studied with the sessile drop method. The results showed that the contact angle was decreased gradu- ally with increasing temperature and the prolonging of holding time. Sound AIN/AIN joints were achieved with the brazing alloy at 1170 ℃ for 10 min. The microstructure of the AIN/AIN joints was examined by scanning electron microscopy （SEM）. It was found that element V played the active role in the interfacial reaction between the ceramic and the brazing alloy, V reacted with N decomposed from AIN, resulted in the formation of V-N compound. Based on the energy-dispersive spectroscopy （EDS） and X-ray diffraction （XRD） analysis results, the V-N reaction product was verified as V2N. The overall reaction during the brazing process can be described by the following equation： 2V ＋ AIN ＋ 2Pd = V2N ＋ Pd2AI. The AIN/AIN joints brazed with the Au-Pd-Co-Ni-V brazing alloy exhibited three-point bend strength of 162.7 MPa at room temperature, and under the bend test the fracture of the joint occurred at the AIN ceramic substrate.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
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
In an attempt to develop low-silver brazing filler metals used for hermetic sealing materials in the vacuum interrupter industry,the ternary Ag-50Cu-5Ga low-silver vacuum brazing filler metal was investigated.The melt...In an attempt to develop low-silver brazing filler metals used for hermetic sealing materials in the vacuum interrupter industry,the ternary Ag-50Cu-5Ga low-silver vacuum brazing filler metal was investigated.The melting temperature was measured by differential scanning calorimetry(DSC),and the brazability of Ag-50Cu-5Ga alloy on copper and metallized copper/kovar were ascertained at 850℃under 1×10-4 Pa in this article.The microstructures of the filler metal and the joints have been analyzed by using scanning electron microscopy(SEM),equipped with an energy dispersive spectroscopy.The results show that vacuum brazing was success to join with copper or metallized copper/kovar using Ag-50Cu-5Ga filler and reliable joints were obtained.There were Ag-rich phase,Cu-rich phase and a fine eutectic structure of Ag-based solid solution and Cu-based solid solution in the copper joints and the width of brazing seam is about 60μm.The joints of kovar alloy to copper after surface nickel plating was composed of AgCu eutectic phase,Ag,Cu,Cu2Ga and CuNi2 phase.The tensile strength was 167 MPa and 150 MPa,respectively.The tensile results of joints show that the joint strengths were equivalent to the traditional brazing filler metals.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
Ti-47Al-2Nb-2Cr-0.15B(mole fraction,%)alloy was vacuum brazed with amorphous and crystalline Ti.25Zr-12.5Cu-12.5Ni-3.0Co-2.0Mo(mass fraction,%)filler alloys,and the melting,spreading and gap filling behaviors of the a...Ti-47Al-2Nb-2Cr-0.15B(mole fraction,%)alloy was vacuum brazed with amorphous and crystalline Ti.25Zr-12.5Cu-12.5Ni-3.0Co-2.0Mo(mass fraction,%)filler alloys,and the melting,spreading and gap filling behaviors of the amorphous and crystalline filler alloys as well as the joints brazed with them were investigated in details.Results showed that the amorphous filler alloy possessed narrower melting temperature interval,lower liquidus temperature and melting active energy compared with the crystalline filler alloy,and it also exhibited better brazeability on the surface of the Ti.47Al.2Nb.2Cr.0.15B alloy.The TiAl joints brazed with crystalline and amorphous filler alloys were composed of two interfacial reaction layers and a central brazed layer.Under the same conditions,the tensile strength of the joint brazed with the amorphous filler alloy was always higher than that with the crystalline filler alloy.The maxmium tensile strength of the joint brazed at 1273 K with the amorphous filler alloy reached 254 MPa.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
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
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
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
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
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
Ni/TiAl composite brazed joints could significantly reduce the aircraft’s weight.However,low interfacial adhesion,coarse and brittle-hard intermetallic compounds(IMCs)seriously limited the application of Ni/TiAl comp...Ni/TiAl composite brazed joints could significantly reduce the aircraft’s weight.However,low interfacial adhesion,coarse and brittle-hard intermetallic compounds(IMCs)seriously limited the application of Ni/TiAl composite joints in the next generation of aerospace applications.So enhanced K4169/TiAl composite joints were investigated by vacuum brazed with(Ni_(53.33)Cr_(20)B_(16.67)Si_(10)/Zr_(25)Ti_(18.75)Ta_(12.5)Ni_(25)Cu_(18.75))composite filler metal(CFM)designed based on cluster-plus-glue-atom model.The shear strength of the joint reached 485 MPa,comparable to the 491 MPa of TiAl substrate.The flat and brittle-hard diffusion reaction layer between Zones I and II was eliminated,simultaneously generating CrB4 dispersion strengthening due to the CFM developed with the interfacial solid-liquid space-time hysteresis effect.In Zones II and III,IMCs all transformed into Niss(Cr,Fe)_([0–88]),Niss(Ti,Al)_([004]),and Niss(Zr,Si)_([11–2])of circular and oval shapes through isothermal solidification.Meanwhile,the residual stresses and hardness were distributed in reticulated cladding characteristics.Thereby,lattice distortion led to solid solution strengthening and increased plastic toughness through crack termination and bridging mechanisms,which inhibited dislocations from plugging and crack propagation.Various interfaces in ZoneⅣwere regulated into semi-and coherent interfaces.Ni3(Ti,Al)/(Ni,Ti,Al)and(Ni,Ti,Al)/AlNi_(2)Ti were composed of higher interfacial bonding energy(2.771 J/m^(2),2.547 J/m^(2))and Ni-Ni covalent bonds.Interfacial covalent bonding and large interfacial bonding energy coupling strengthened Zone IV.Consequently,cracks initiated at the(Ni,Ti,Al)[013]/Ti3Al_([010])and expanded rapidly into TiAl substrate.Therefore,applying this method to design CFMs and regulate the phase,grain morphology,and interface’s fine structure could provide new pathways for dissimilar hard-to-join metals.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 technique of creep feed grinding is most suitable for geometrical shaping, and therefore has been expected to improve effectively material removal rate and surface quality of components with complex profile. This ...The technique of creep feed grinding is most suitable for geometrical shaping, and therefore has been expected to improve effectively material removal rate and surface quality of components with complex profile. This article studies experimentally the effects of process parameters （i.e. wheel speed, workpiece speed and depth of cut） on the grindability and surface integrity of cast nickel-based superalloys, i.e. K424, during creep feed grinding with brazed cubic boron nitride （CBN） abrasive wheels. Some important factors, such as grinding force and temperature, specific grinding energy, size stability, surface topography, microhardhess and microstructure alteration of the sub-surface, residual stresses, are investigated in detail. The results show that during creep feed grinding with brazed CBN wheels, low grinding temperature at about 100 ℃ is obtained though the specific grinding energy of nickel-based superalloys is high up to 200-300 J/mm^3. A combination of wheel speed 22.5 m/s, workpiece speed 0.1 m/min, depth of cut 0.2 mm accomplishes the straight grooves with the expected dimensional accuracy. Moreover, the compressive residual stresses are formed in the bum-free and crack-free ground surface.展开更多
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supported by the National Nature Science Foundation of China (Grant Nos. 51372049, 51321061 and U1537206)
文摘Porous Si3N4 was brazed to Invar alloy in this study, and Ag-Cu-Ti/Cu/Ag-Cu multi-layered filler was designed to inhibit the formation of Fe2Ti and Ni3Ti intermetallic compounds. The effects of the brazing temperature and the thickness of Cu interlayer on the microstructure and mechanical properties of brazed joints were investigated. The typical microstructure of the joint brazed with multi-layered filler was porous Si3N4/TiN ＋ Ti5Si3/Ag-Cu eutectic[Cu[Ag-Cu eutectic/Cu-rich layer ＋ diffusion layer/Invar. When the brazing temperature increased, the reaction layer at the ceramic/filler interface grew thicker and the Cu interlayer turned thinner. As the thickness of Cu interlayer increased from 50 to 150 μm, the joint strength first increased and then decreased. In this research, the maximum shear strength （73 MPa） was obtained when being brazed at 1173 K with a 100 μm Cu interlayer applied in the filler, which was 55% higher than that brazed with single Ag-Cu-Ti brazing alloy and had reached 86% of the ceramic. The release of residual stress and the barrier effect of Cu interlayer to inhibit the formation of Fe2Ti and Ni3Ti intermetallics played the major role in the improvement of joint strength.
基金supported by the National Natural Science Foundation of China (Grant No. 51574177)the China Natural Founds for Distinguished Young Scientists (Grant No. 51325401)the National High Technology Research and Development Program of China (“863” Program, Granted No. 2015AA042504)
文摘Vacuum brazing was successfully used to join Ti-22Al-25Nb alloy using Ti-Ni-Nb brazing alloys prepared by arc-melting. The influence of Nb content in the Ti-Ni-Nb brazing alloys on the interfacial microstructure and mechanical properties of the brazed joints was investigated. The results showed that the interfacial microstructure of brazed joint consisted of B2, O, ？3, and Ti2 Ni phase, while the width of brazing seams varied at different Nb contents. The room temperature shear strength reached359 MPa when the joints were brazed with eutectic Ti40Ni40Nb20 alloy at 1180？C for 20 min, and it was321, 308 and 256 MPa at 500, 650 and 800？C, respectively. Cracks primarily initiated and propagated in ？3compounds, and partially traversed B2＋O region. Moreover, the fracture surface displayed typical ductile dimples when cracks propagated through B2＋O region, which was favorable for the mechanical properties of the brazed joint.
基金sponsored by National Natural Science Foundation (No.50175021)National Key Laboratory of Advanced Welding Production Technology of Harbin Institute of Technology,China.
文摘The brazing of TiC cermet to iron was carried out at 1223K for 5-20min using Ag-Cu-Zn filler metal. The formation phase and interface structure of the joints were investigated by electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction (XRD), and the joint strength was tested by shearing method. The results showed: there occurred three new formation phases, Cu(s.s), FeNi and Ag(s.s) in TiC cermet/iron joint. The interface structure was expressed as TiC cermet/Cu(s.s)+FeNi/Ag(s.s)+a little Cu(s.s)+a little FeNi/Cu(s.s)+FeNi/iron, With brazing time increasing, there appeared highest shear strength of the joints, the value of which was up to 252.2MPa when brazing time was 10min.
基金sponsored by the National Natural Science Foundation of China (Nos. 59905022, 50475160, 51275497 and 51410105004)the Aeronautical Science Foundation of China (No. 2008ZE21005)
文摘An Au-Pd-Co-Ni-V brazing alloy was designed for AIN ceramic joining. Its wettability on AIN was studied with the sessile drop method. The results showed that the contact angle was decreased gradu- ally with increasing temperature and the prolonging of holding time. Sound AIN/AIN joints were achieved with the brazing alloy at 1170 ℃ for 10 min. The microstructure of the AIN/AIN joints was examined by scanning electron microscopy （SEM）. It was found that element V played the active role in the interfacial reaction between the ceramic and the brazing alloy, V reacted with N decomposed from AIN, resulted in the formation of V-N compound. Based on the energy-dispersive spectroscopy （EDS） and X-ray diffraction （XRD） analysis results, the V-N reaction product was verified as V2N. The overall reaction during the brazing process can be described by the following equation： 2V ＋ AIN ＋ 2Pd = V2N ＋ Pd2AI. The AIN/AIN joints brazed with the Au-Pd-Co-Ni-V brazing alloy exhibited three-point bend strength of 162.7 MPa at room temperature, and under the bend test the fracture of the joint occurred at the AIN ceramic substrate.
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.
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the National Key R&D Program of China(Grant No.2017YFB0305702).
文摘In an attempt to develop low-silver brazing filler metals used for hermetic sealing materials in the vacuum interrupter industry,the ternary Ag-50Cu-5Ga low-silver vacuum brazing filler metal was investigated.The melting temperature was measured by differential scanning calorimetry(DSC),and the brazability of Ag-50Cu-5Ga alloy on copper and metallized copper/kovar were ascertained at 850℃under 1×10-4 Pa in this article.The microstructures of the filler metal and the joints have been analyzed by using scanning electron microscopy(SEM),equipped with an energy dispersive spectroscopy.The results show that vacuum brazing was success to join with copper or metallized copper/kovar using Ag-50Cu-5Ga filler and reliable joints were obtained.There were Ag-rich phase,Cu-rich phase and a fine eutectic structure of Ag-based solid solution and Cu-based solid solution in the copper joints and the width of brazing seam is about 60μm.The joints of kovar alloy to copper after surface nickel plating was composed of AgCu eutectic phase,Ag,Cu,Cu2Ga and CuNi2 phase.The tensile strength was 167 MPa and 150 MPa,respectively.The tensile results of joints show that the joint strengths were equivalent to the traditional brazing filler metals.
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Foundation item:Project(51865012)supported by the National Natural Science Foundation of ChinaProject(2016005)supported by the Open Foundation of National Engineering Research Center of Near-net-shape Forming for Metallic Materials,China+2 种基金Project(GJJ170372)supported by the Science Foundation of Educational Department of Jiangxi Province,ChinaProject(JCKY2016603C003)supported by the GF Basic Research Project,ChinaProject(JPPT125GH038)supported by the Research Project of Special Furnishment and Part,China
文摘Ti-47Al-2Nb-2Cr-0.15B(mole fraction,%)alloy was vacuum brazed with amorphous and crystalline Ti.25Zr-12.5Cu-12.5Ni-3.0Co-2.0Mo(mass fraction,%)filler alloys,and the melting,spreading and gap filling behaviors of the amorphous and crystalline filler alloys as well as the joints brazed with them were investigated in details.Results showed that the amorphous filler alloy possessed narrower melting temperature interval,lower liquidus temperature and melting active energy compared with the crystalline filler alloy,and it also exhibited better brazeability on the surface of the Ti.47Al.2Nb.2Cr.0.15B alloy.The TiAl joints brazed with crystalline and amorphous filler alloys were composed of two interfacial reaction layers and a central brazed layer.Under the same conditions,the tensile strength of the joint brazed with the amorphous filler alloy was always higher than that with the crystalline filler alloy.The maxmium tensile strength of the joint brazed at 1273 K with the amorphous filler alloy reached 254 MPa.
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.
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financially supported by the National Natural Science Foundation of China(Nos.52275314 and 52075074).
文摘Ni/TiAl composite brazed joints could significantly reduce the aircraft’s weight.However,low interfacial adhesion,coarse and brittle-hard intermetallic compounds(IMCs)seriously limited the application of Ni/TiAl composite joints in the next generation of aerospace applications.So enhanced K4169/TiAl composite joints were investigated by vacuum brazed with(Ni_(53.33)Cr_(20)B_(16.67)Si_(10)/Zr_(25)Ti_(18.75)Ta_(12.5)Ni_(25)Cu_(18.75))composite filler metal(CFM)designed based on cluster-plus-glue-atom model.The shear strength of the joint reached 485 MPa,comparable to the 491 MPa of TiAl substrate.The flat and brittle-hard diffusion reaction layer between Zones I and II was eliminated,simultaneously generating CrB4 dispersion strengthening due to the CFM developed with the interfacial solid-liquid space-time hysteresis effect.In Zones II and III,IMCs all transformed into Niss(Cr,Fe)_([0–88]),Niss(Ti,Al)_([004]),and Niss(Zr,Si)_([11–2])of circular and oval shapes through isothermal solidification.Meanwhile,the residual stresses and hardness were distributed in reticulated cladding characteristics.Thereby,lattice distortion led to solid solution strengthening and increased plastic toughness through crack termination and bridging mechanisms,which inhibited dislocations from plugging and crack propagation.Various interfaces in ZoneⅣwere regulated into semi-and coherent interfaces.Ni3(Ti,Al)/(Ni,Ti,Al)and(Ni,Ti,Al)/AlNi_(2)Ti were composed of higher interfacial bonding energy(2.771 J/m^(2),2.547 J/m^(2))and Ni-Ni covalent bonds.Interfacial covalent bonding and large interfacial bonding energy coupling strengthened Zone IV.Consequently,cracks initiated at the(Ni,Ti,Al)[013]/Ti3Al_([010])and expanded rapidly into TiAl substrate.Therefore,applying this method to design CFMs and regulate the phase,grain morphology,and interface’s fine structure could provide new pathways for dissimilar hard-to-join metals.
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National Basic Research Program of China (2009CB724403)Program for Changjiang Scholars and Innovative Research Team in University (IRT0837)Program for New Century Excellent Talents in University from Ministry of Education of China (NCET-07-0435)
文摘The technique of creep feed grinding is most suitable for geometrical shaping, and therefore has been expected to improve effectively material removal rate and surface quality of components with complex profile. This article studies experimentally the effects of process parameters （i.e. wheel speed, workpiece speed and depth of cut） on the grindability and surface integrity of cast nickel-based superalloys, i.e. K424, during creep feed grinding with brazed cubic boron nitride （CBN） abrasive wheels. Some important factors, such as grinding force and temperature, specific grinding energy, size stability, surface topography, microhardhess and microstructure alteration of the sub-surface, residual stresses, are investigated in detail. The results show that during creep feed grinding with brazed CBN wheels, low grinding temperature at about 100 ℃ is obtained though the specific grinding energy of nickel-based superalloys is high up to 200-300 J/mm^3. A combination of wheel speed 22.5 m/s, workpiece speed 0.1 m/min, depth of cut 0.2 mm accomplishes the straight grooves with the expected dimensional accuracy. Moreover, the compressive residual stresses are formed in the bum-free and crack-free ground surface.
