This paper describes a simple method for the preparation of L-proline stationary phase bonded to silica gel and characterization of the bonded phase by IR spectrometry, elemental analysis and nitrogen adsorption metho...This paper describes a simple method for the preparation of L-proline stationary phase bonded to silica gel and characterization of the bonded phase by IR spectrometry, elemental analysis and nitrogen adsorption method at low temperature.The enantiomeric resolutions of 3-(2-pyridyl)-3-aminopropionic acid and 2,3-diaminobutanoic acid on the bonded phase were carried out.展开更多
Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the ...Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the base material region. The microstructure of the particulate segregation region consists of alumina particulate and Al alloy matrix with the Al 2Cu and MgAl 2O 4. It contains more and smaller alumina particulates compared with the base material region. The TLP bonded joints have the tensile strength of 150 MPa ～200 MPa and the shear strength of 70 MPa ～100 MPa . With increasing tensile stress, cracks initiate in the particulate segregation region, especially in the particulate/particulate interface and the particulate/matrix interface, and propagate along particulate/matrix interface, througth thin matrix metal and by linking up the close cracks. The particulate segregation region is the weakest during tensile testing and shear testing due to obviously increased proportion of weak bonds (particulate particulate bond and particulate matrix bond).展开更多
In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the fille...In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.展开更多
Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.M...Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.Microstructural evaluations using electron probe microanalysis(EPMA)and electron backscattered diffraction(EBSD)show that the central eutectic phases present in the athermally solidified zone(ASZ)are Ni_(3)B,Ni_(2)Si,and CrB,and the precipitates formed in the diffusion-affected zone(DAZ)are MoB,CrB_(2),and Mo_(2)B_(5).According to the results,decreasing the filler thickness as well as increasing the holding time helps realize the completion of isothermal solidification and reduction in the density of precipitates in the DAZ,leading to a joint with more uniform properties.Diffusion of boron and silicon to longer distances with increasing holding time causes the removal of Cr-rich borides in the DAZ and the formation of Mo-rich silicide at the joint interface.Decrease in hardness of ASZ and DAZ due to the elimination of brittle phases in these zones during long holding time causes more uniform hardness distribution in the joint area.The best results are obtained for the sample joined with the 35μm-thick filler metal for 640 min holding time.展开更多
One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm ...One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.展开更多
Ti_(3)SiC_(2) ceramic and SUS430 ferritic stainless steel were welded by the transient liquid phase(TLP)diffusion bonding method using an Al interlayer at 850-1050℃ in vacuum.The evolution of phase and morphology at ...Ti_(3)SiC_(2) ceramic and SUS430 ferritic stainless steel were welded by the transient liquid phase(TLP)diffusion bonding method using an Al interlayer at 850-1050℃ in vacuum.The evolution of phase and morphology at the interface and bonding strength were systematically investigated.The results show that Ti_(3)SiC_(2) and SUS430 were well bonded at 900-950℃.Three reaction zones were observed at the interface.At the joint interface area adjacent to alloy,the alloy completely reacted with liquid Al to form Al_(86)Fe_(14).At Ti_(3)SiC_(2)/Al interface,Ti and Si diffused outward from Ti_(3)SiC_(2) into the molten Al to form Fe_(3)Al+Al_(5)FeSi+TiAl_(3) zone.Adjacent to Ti_(3)SiC_(2) matrix,Ti_(3)Si(Al)C_(2)+TiCx zone was formed by the loss of Si.The evolution mechanism of TLP-bonded joints was discussed based on the interface microstructure and product phases.In addition,the tensile strength of the joint increased with increasing bonding temperature.The corresponding maximum value of 59.7 MPa was obtained from SUS430/Al(10μm)/Ti_(3)SiC_(2) joint prepared at 950℃.展开更多
Transient liquid phase（TLP） bonding of IN738 LC superalloy was carried out using a rapidly solidified MBF-15 Ni-based foil. The effects of bonding temperature（1130–1170 °C） and time（5–120 min） as well as ...Transient liquid phase（TLP） bonding of IN738 LC superalloy was carried out using a rapidly solidified MBF-15 Ni-based foil. The effects of bonding temperature（1130–1170 °C） and time（5–120 min） as well as foil thickness（35–140 μm） were studied on the microstructure of joint region and its mechanical properties. The solidification sequence in the joint region was found to be（i） formation of γ solid solution in the isothermally solidified zone, followed by（ii） ternary eutectic of γ ＋ Ni3 B ＋ Cr B, and finally（iii） binary eutectic of γ ＋ Ni3 Si in the athermally solidified zone. Fine Ni3 Si particles were also formed via a solid state transformation within the γ matrix in the vicinity of eutectic products. A deviation of isothermal solidification kinetics from the standard parabolic TLP model was observed by increasing the bonding temperature to 1170 °C, which resulted in the formation of eutectic constituents at the joint centerline.The analysis of mechanical and fractographic test results revealed that the samples with complete isothermal solidification exhibit the highest shear strength, whereas the hard eutectic constituents act as preferential failure sites and lead to a significant reduction in the joint shear strength in samples with incomplete isothermal solidification.展开更多
The open-cell Al foam core sandwiches（AFCSs） were successfully fabricated by using a specially designed Zn-Al-Cu based filler alloy via vibration aided liquid phase bonding method.The effects of the vibration on the...The open-cell Al foam core sandwiches（AFCSs） were successfully fabricated by using a specially designed Zn-Al-Cu based filler alloy via vibration aided liquid phase bonding method.The effects of the vibration on the bonding seam were investigated and the bonding strength between Al foam core and solid Al alloy face sheet was tested by shearing tests.The results show that vibration can significantly improve the quality of the bonding and the shearing strength of the bonding seam,which implies that this joining method has a good potential in practical applications.展开更多
Transient liquid phase bonding of two dissimilar alloys Al 2024 and Ti?6Al?4V using Cu?22%Zn interlayer was carried out at 510 °C under vacuum of 0.01 Pa for various bonding time. In order to characterize the mic...Transient liquid phase bonding of two dissimilar alloys Al 2024 and Ti?6Al?4V using Cu?22%Zn interlayer was carried out at 510 °C under vacuum of 0.01 Pa for various bonding time. In order to characterize the microstructure evolution in the joint zone, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were applied. The results show that joint formation is attributed to the solid-state diffusion of Cu and Zn into Ti?6Al?4V and Al 2024 alloys followed by eutectic formation and isothermal solidification along the Cu?Zn/Al 2024 interface. The hardness of the joints at the interface increases with an increase in bonding time which can be attributed to formation of intermetallic compounds such as Al2Cu, TiCu3, Al4.2Cu3.2Zn0.7, Al0.71Zn0.29, Ti2Cu, TiAl3 and TiZn16 in the joint zone. Moreover, shear strength of the joint reaches the highest value of 37 MPa at bonding time of 60 min.展开更多
This study focuses on the transient liquid phase(TLP)bonding of DD5 single-crystal superalloy to Cr Co Nibased medium-entropy alloy(MEA)using a BNi-2 filler alloy.The microstructure and mechanical properties of the TL...This study focuses on the transient liquid phase(TLP)bonding of DD5 single-crystal superalloy to Cr Co Nibased medium-entropy alloy(MEA)using a BNi-2 filler alloy.The microstructure and mechanical properties of the TLP-bonded DD5/MEA joint were evaluated,and the microstructural evolution mechanism was investigated.The formation of the isothermal solidification zone(ISZ)depended on the diffusion of the melting-point depressants(Si and B elements)from the liquid filler into the DD5 and MEA substrates,as well as the dissolution of the substrates.Boron diffused along theγchannel of DD5 and reacted to form M_(5)B_(3)boride,herein referred to as the diffusion-affected zone(DAZ I).Similarly,the Cr_(5)B_(3)boride precipitated in the Ni-rich MEA matrix adjacent to the MEA substrate(i.e.,DAZ II).Additionally,a coherent orientation of[0]_(BCY)//[011]_(FCC)and(002)_(BCY)//(200)_(FCC)was detected between M_(5)B_(3)boride with a body-centered tetragonal(BCT)structure and the face-centered cubic(FCC)matrix.The performance of the joint was dominated by the properties of the bonding seam.As the bonding time increased from 20to 80 min,the athermal solidification zone(including eutectic microstructure)was gradually replaced by the ISZ exhibiting excellent plastic deformation capability,and the shear strength of the joint was improved.The maximum shear strength(752 MPa)was achieved when the eutectic-free joint was bonded at 1050℃ for 80 min.The fracture morphology revealed a mixture mode,indicating the initiation of cracks in the DAZ II,mainly propagating in the ISZ,and passing through the DAZ I.展开更多
The transient liquid phase(TLP)bonding of CoCuFeMnNi high entropy alloy(HEA)was studied.The TLP bonding was performed using AWS BNi-2 interlayer at 1050℃ with the TLP bonding time of 20,60,180 and 240 min.The effect ...The transient liquid phase(TLP)bonding of CoCuFeMnNi high entropy alloy(HEA)was studied.The TLP bonding was performed using AWS BNi-2 interlayer at 1050℃ with the TLP bonding time of 20,60,180 and 240 min.The effect of bonding time on the joint microstructure was characterized by SEM and EDS.Microstructural results confirmed that complete isothermal solidification occurred approximately at 240 min of bonding time.For samples bonded at 20,60 and 180 min,athermal solidification zone was formed in the bonding area which included Cr-rich boride and Mn3Si intermetallic compound.For all samples,theγsolid solution was formed in the isothermal solidification zone of the bonding zone.To evaluate the effect of TLP bonding time on mechanical properties of joints,the shear strength and micro-hardness of joints were measured.The results indicated a decrement of micro-hardness in the bonding zone and an increment of micro-hardness in the adjacent zone of joints.The minimum and maximum values of shear strength were 100 and 180 MPa for joints with the bonding time of 20 and 240 min,respectively.展开更多
This work has successfully proposed a solution to produce robust Nb-interlayer-inserted Ti-6Al-4V/Si_(3)N_(4)joints optimized for a maximum operating temperature of 873 K;transient liquid phase bonding(TLPB)of Ti-6Al-...This work has successfully proposed a solution to produce robust Nb-interlayer-inserted Ti-6Al-4V/Si_(3)N_(4)joints optimized for a maximum operating temperature of 873 K;transient liquid phase bonding(TLPB)of Ti-6Al-4V/Nb side was carried out with Cu and Ni fillers to suppress brittle intermetallic compounds(IMCs),whereas brazing of Nb/Si_(3)N_(4)side was performed using a highly ductile Ti-added Ag-rich filler for effective residual-stress relaxation.A sound yet simple one-step bonding process incorporating simul-taneous TLPB and brazing was achieved with a relatively short holding time of 10 min at 1213 K.TLPB of Ti-6Al-4V/Nb side with Cu and Ni foils of 2-μm-thick each as a laminated filler suppressed brittle Ti-based IMCs and developed a homogenized microstructure consisting mainly of(α+β)-Ti via isothermal solidification.Meanwhile,brazing of Nb/Si_(3)N_(4)side with 100-μm-thick SILVER-ABA filler(92.75Ag-5Cu-1Al-1.25Ti mass%)foil enhanced interfacial bonding with sufficient total Ti content and accommodated residual stress better than conventional eutectic Ag-Cu-based fillers,and it was verified by finite element analysis with consideration of materials’temperature-dependent elasto-plastic properties.All joints with a bonding area of 10 mm×10 mm were tested via symmetrical four-point bending from room temper-ature(RT)to 873 K fractured from Nb/Si_(3)N_(4)side.When re-heating the joints from RT to 673 K,frac-ture initiation gradually shifted from Si_(3)N_(4)towards interfacial-compounds/Si_(3)N_(4)interface and bending strengths maintained∼220 MPa as weakening of SILVER-ABA filler was compensated by residual-stress relaxation in Si_(3)N_(4).When tested at 873 K,joints fractured mainly across the Ag-rich solid solution in a ductile manner and bending strength degraded by∼20%to 171 MPa as weakening of SILVER-ABA filler dominated.展开更多
The effects of thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. Wi...The effects of thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. With the maximum cyclic temperature of 1 173～1 223 K , the minimum cyclic temperature of 1 073～1 093 K , the heating velocity of 30～50 K/s , the cooling velocity of 15～20 K/s , the cycle numbers of 15～20 and bonding pressure is 13 MPa , the tensile strength of joint is more than 380 MPa , exceeding 80% of that of Ti.展开更多
In this study, a two-step heating process is introduced for transient liquid phase ( TLP) diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating ...In this study, a two-step heating process is introduced for transient liquid phase ( TLP) diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating step is addressed to melt the interlayer, followed by the second step to complete isothermal solidification at a low temperature. The most critical feature of our new method is producing a non-planar interface at the T9/ heat resistant steels joint. We propose a transitional liquid phase bonding of T91 heat resistant steels by this approach. Since joint microstructures have been studied, we tested the tensile strength to assess joint mechanical property. The result indicates that the solidified bond may contain a primary solid-solution, similar composition to the parent metal and free from precipitates. Joint tensile strength of the joint is not lower than parent materials. Joint bend's strengths are enhanced due to the higher metal-to-metal junction producing a non-planar bond lines. Nevertheless, the traditional transient liquid phase diffusion bonding produces planar ones. Bonding parameters of new process are 1 260 °C for 0. 5 min and 1 230 °C fo r 4 min.展开更多
Ni-base alloy DZ468 has been joined by transient liquid phase bonding technique with a newly developed Co-based filler. The microstructures of the Co-base filler and the joint, the effects of heat treatment on microst...Ni-base alloy DZ468 has been joined by transient liquid phase bonding technique with a newly developed Co-based filler. The microstructures of the Co-base filler and the joint, the effects of heat treatment on microstructure and hardness of the joint have been investigated by various experimental methods. Results show that the Co-base filler consists of γ, M2B, M5B3 and M23B6 phases. Because of the interdiffusion between the base metal and the filler, γ, MC, M5B3 and M23B6 phases are formed in the bonding zone. And localized liquidation of substrate occurs in the diffusion affected zone, with MC and M3B2 precipitating in this area. During heat treatment, the volume of the intermetallic phases in the bonding zone resulting from incomplete isothermal solidification decreases obviously. On the contrary, the width of the diffusion affected zone increases at the solution stage and subsequently decreases at the aging stages.展开更多
Ductile transient liquid phase(TLP)bonding joints reinforced by multiple precipitates were produced using novel pre-sintered coatings and Au-Si fillers;therefore,the highest strength of NiTi/sapphire joints brazed at ...Ductile transient liquid phase(TLP)bonding joints reinforced by multiple precipitates were produced using novel pre-sintered coatings and Au-Si fillers;therefore,the highest strength of NiTi/sapphire joints brazed at 460℃ for 30 min reached 72 MPa.The pre-sintering process improved the surface-active of sapphire by forming metastable Ti_(3)O and non-stoichiometric Al_(2)O_(3).The typical brazing seam consisted of O-rich compounds,TiSi_(2),and Ti-Ni-Si,wherein the O-rich phase featured different crystallinity depending on the oxygen content.The sapphire/seam interface was either a nanoscale diffusion region or a Si-rich amorphous layer.The breakdown of the Stokes-Einstein relation(SER)occurred,and the deviation from SER increased with a higher cooling rate.The influence of coating thickness was reflected in(i)the supercooling related to the viscosity and fractional exponent of liquids and(ii)the microstructural change of the joint related to the driving force for crystal growth.This work presented a new strategy for joining ceramics to metals at lower temperatures but using the joint at higher temperatures;furthermore,gave an insight into the microstructure evolution and kinetics behaviors based on supercooling in a transient liquid phase bonding joint.展开更多
Microstructures and mechanical properties of transient liquid phase （TLP） bonded magnesium metal matrix composite （ MMC） joints using copper interlayer have been investigated. With an increase of bonding times fro...Microstructures and mechanical properties of transient liquid phase （TLP） bonded magnesium metal matrix composite （ MMC） joints using copper interlayer have been investigated. With an increase of bonding times from 5 min to 50 min at bonding temperature of 510 ℃ , the average concentration of copper in the bonded zone decreased, the microstructure in the zone changed from Cu, α-Mg and CuMg2 to α-Mg, CuMg2 and TiC, and mechanical properties of the joint increased. The shear strength of the joint bonded at 510 ℃ for 50 min reached 64 MPa due to the metallurgical bonding of the joint and improving its homogeneity of composition and microstructure. It is favorable to increase the bonding time for improving mechanical properties of TLP bonded magnesium MMC joint.展开更多
High temperature oxidation behavior of two kinds of nitride bonded SiC based refractories wtls bwestigated at I 100-1 .500℃ by means of X-ray di[fractometer, scanning electronic microscopy and thermogravimetry. The r...High temperature oxidation behavior of two kinds of nitride bonded SiC based refractories wtls bwestigated at I 100-1 .500℃ by means of X-ray di[fractometer, scanning electronic microscopy and thermogravimetry. The results show that ： （1） with the temperature im＇reasing, the oxidation mass increment rote of the specimen increases.first and then. decreases, and oxidation passi＇va tion occttrs; （2） the oxidation resistance of SiAION bonded SiC refractories is superior to that of Si3N4 botlded SiC refractories ; （3） high temperature oxidtttion resuits itt the increase of compressive strength at room temperature of SiC based refractoviesiaes comlmred with specimen before oxidatiotl; the compressive strength of SIMON bonded SiC specimens oxidized at high temperatures decreases with the increase of the temperature as a result of formation amt burst of surfhce bubble, while the decrease of compressive strength of Sign4 bonded SiC specimens oxidized at high temperatures is owitng to the bwrease of the consistency of netlike crack assoeiated with cristobalite transfornuttion during cooling.展开更多
Gaseous phases of carbon-containing and metastable oxides will be resulted from the carbonization of phenolic resin binders and the reduced reactions between C and oxides at high temperatures in carbon-containing refr...Gaseous phases of carbon-containing and metastable oxides will be resulted from the carbonization of phenolic resin binders and the reduced reactions between C and oxides at high temperatures in carbon-containing refractories. With the in-situ catalysis technique, these gaseous phases can be transformed to one-or two-dimensional bonding phases by deposition,which is favorable for the improvement on strength and toughness of carboncontaining refractories,especially low carbon refractories. The research results reveal that：（ 1） the amorphous carbon resulted from phenolic resin can be transformed to carbon nanotubes,thus,the oxidation peak temperature is raised from 506 to 664. 6 ℃;（ 2） onedimensional whiskers of MgO or Mg Al2 O4 can be in-situ formed in MgO-C refractories, and their CMOR,CCS,rupture displacement and residual CCS（ two water quenching cycles,1 100 ℃） are increased by 66%,47%,13% and 26%,respectively;（ 3） two-dimensional array structure of flake β-SiAlON can be in-situ formed in Al2 O3-C refractories,which improves the material strength by 60% and decreases the residual strength after thermal shock by only 4. 5 MPa. It is believed that the in-situ formation of one-or two-dimensional bonding phases at high temperatures can improvethe comprehensive thermal physical properties of carboncontaining refractories,and will be the developing trend of the strengthening and toughening of low carbon-containing refractories.展开更多
The influence of SiO2 on bonding phase fluidity was studied by measuring the projected area of tablets prepared using mixtures of fine iron ore and chemical reagents after sintering. The microstructure of samples was ...The influence of SiO2 on bonding phase fluidity was studied by measuring the projected area of tablets prepared using mixtures of fine iron ore and chemical reagents after sintering. The microstructure of samples was observed by optical microscope and SEM. Moreover, the relationship between SiO2 and bonding phase fluidity and microstructure was analyzed by CaO-Fe2O3-SiO2 system 1 300℃ isothermal section diagram. The main experimental conditions are as follows： in the composition of the bonding phase,CaO is 10%, 15% ,and 20%; SiO2 is 2% and 6% ; sintering temperature is 1 250, 1 300 and 1 350 ℃ ; the sample cooling rate is quick. The results of the study show that.① The fluidity of the binding phase decreases with the increase of SiO2 content. Moreover,fluidity increases as the sintering temperature increases; however, when the CaO content is 10% （relatively low proportion）, the lifting temperature has limited effect on fluidity improvement. ② The hematite proportion of the microstructure increases as the SiO2 content increases. ③ When SiO2 content increases, the solid phase ratio in the bonding phase grows,while the liquid phase ratio diminishes. Moreover the extension of the SiO2 content in the liquid phase is larger than that in the solid phase.展开更多
文摘This paper describes a simple method for the preparation of L-proline stationary phase bonded to silica gel and characterization of the bonded phase by IR spectrometry, elemental analysis and nitrogen adsorption method at low temperature.The enantiomeric resolutions of 3-(2-pyridyl)-3-aminopropionic acid and 2,3-diaminobutanoic acid on the bonded phase were carried out.
文摘Transient liquid phase (TLP) bonded aluminium based metal matrix composite (MMC) joints can be classified into three distinct regions, i.e. the particulate segregation region, the denuded particulate region and the base material region. The microstructure of the particulate segregation region consists of alumina particulate and Al alloy matrix with the Al 2Cu and MgAl 2O 4. It contains more and smaller alumina particulates compared with the base material region. The TLP bonded joints have the tensile strength of 150 MPa ～200 MPa and the shear strength of 70 MPa ～100 MPa . With increasing tensile stress, cracks initiate in the particulate segregation region, especially in the particulate/particulate interface and the particulate/matrix interface, and propagate along particulate/matrix interface, througth thin matrix metal and by linking up the close cracks. The particulate segregation region is the weakest during tensile testing and shear testing due to obviously increased proportion of weak bonds (particulate particulate bond and particulate matrix bond).
文摘In order to investigate the microstructure evolution and gain complete isothermal solidification time, transient liquid phase （TLP） bonding of IN-738LC superalloy was carried out using powdered AMS 4777 as the filler metal. The influence of gap size and bonding time on the joints was investigated. For example, complete isothermal solidification time for 40μm gap size was obtained as 45 min. In the case of lack of completion of isothermal solidification step, the remained molten interlayer cooled in the bonding zone under non-equilibrium condition andγ–γ′ eutectic phase formed in that area. The relationship between gap size and holding time was not linear. With the increase in gap size, eutectic phase width became thicker. In the diffusion affected zone, a much larger amount of alloying elements were observed reaching a peak. These peaks might be due to the formation of boride or silicide intermetallic. With the increase in gap size, the time required for bonding will increase, so the alloying elements have more time for diffusion and distribution in farther areas. As a result, concentrations of alloying elements decreased slightly with the increase in the gap size. The present bi-phasic model did not properly predict the complete isothermal solidification time for IN-738LC-AMS 4777-IN-738LC TLP bonding system.
文摘Transient liquid phase(TLP)bonding was investigated in Hastelloy-X samples with different filler metal thicknesses(20,35,50,65,and 100μm)and holding time(5,20,80,320,and 640 min)to obtain optimum bonding parameters.Microstructural evaluations using electron probe microanalysis(EPMA)and electron backscattered diffraction(EBSD)show that the central eutectic phases present in the athermally solidified zone(ASZ)are Ni_(3)B,Ni_(2)Si,and CrB,and the precipitates formed in the diffusion-affected zone(DAZ)are MoB,CrB_(2),and Mo_(2)B_(5).According to the results,decreasing the filler thickness as well as increasing the holding time helps realize the completion of isothermal solidification and reduction in the density of precipitates in the DAZ,leading to a joint with more uniform properties.Diffusion of boron and silicon to longer distances with increasing holding time causes the removal of Cr-rich borides in the DAZ and the formation of Mo-rich silicide at the joint interface.Decrease in hardness of ASZ and DAZ due to the elimination of brittle phases in these zones during long holding time causes more uniform hardness distribution in the joint area.The best results are obtained for the sample joined with the 35μm-thick filler metal for 640 min holding time.
文摘One of the challenges for bimetal manufacturing is the joining process.Hence,transient liquid phase(TLP)bonding was performed between 304L stainless steel and Cp-Ti using an Ag-Cu interlayer with a thickness of 75μm for bonding time of 20,40,60,and 90 min.The bonding temperature of 860℃ was considered,which is under the β transus temperature of Cp-Ti.During TLP bonding,various intermetallic compounds(IMCs),including Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe),Ti_(2)(Cu,Ag),and Ti_(2)Cu from 304L toward Cp-Ti formed in the joint.Also,on the one side,with the increase in time,further diffusion of elements decreases the blocky IMCs such as Ti_(5)Cr_(7)Fe_(17),(Cr,Fe)_(2)Ti,Ti(Cu,Fe)in the 304L diffusion-affected zone(DAZ)and reaction zone,and on the other side,Ti_(2)(Cu,Ag)IMC transformed into fine morphology toward Cp-Ti DAZ.The microhardness test also demonstrated that the(Cr,Fe)_(2)Ti+Ti_(5)Cr_(7)Fe_(17) IMCs in the DAZ on the side of 304L have a hardness value of HV 564,making it the hardest phase.The maximum and minimum shear strength values are equal to 78.84 and 29.0 MPa,respectively.The cleavage pattern dominated fracture surfaces due to the formation of brittle phases in dissimilar joints.
基金supported by the National Natural Science Foundation of China(No.52001179)Natural Science Foundation of Shandong Province,China(No.ZR2020ME019).
文摘Ti_(3)SiC_(2) ceramic and SUS430 ferritic stainless steel were welded by the transient liquid phase(TLP)diffusion bonding method using an Al interlayer at 850-1050℃ in vacuum.The evolution of phase and morphology at the interface and bonding strength were systematically investigated.The results show that Ti_(3)SiC_(2) and SUS430 were well bonded at 900-950℃.Three reaction zones were observed at the interface.At the joint interface area adjacent to alloy,the alloy completely reacted with liquid Al to form Al_(86)Fe_(14).At Ti_(3)SiC_(2)/Al interface,Ti and Si diffused outward from Ti_(3)SiC_(2) into the molten Al to form Fe_(3)Al+Al_(5)FeSi+TiAl_(3) zone.Adjacent to Ti_(3)SiC_(2) matrix,Ti_(3)Si(Al)C_(2)+TiCx zone was formed by the loss of Si.The evolution mechanism of TLP-bonded joints was discussed based on the interface microstructure and product phases.In addition,the tensile strength of the joint increased with increasing bonding temperature.The corresponding maximum value of 59.7 MPa was obtained from SUS430/Al(10μm)/Ti_(3)SiC_(2) joint prepared at 950℃.
文摘Transient liquid phase（TLP） bonding of IN738 LC superalloy was carried out using a rapidly solidified MBF-15 Ni-based foil. The effects of bonding temperature（1130–1170 °C） and time（5–120 min） as well as foil thickness（35–140 μm） were studied on the microstructure of joint region and its mechanical properties. The solidification sequence in the joint region was found to be（i） formation of γ solid solution in the isothermally solidified zone, followed by（ii） ternary eutectic of γ ＋ Ni3 B ＋ Cr B, and finally（iii） binary eutectic of γ ＋ Ni3 Si in the athermally solidified zone. Fine Ni3 Si particles were also formed via a solid state transformation within the γ matrix in the vicinity of eutectic products. A deviation of isothermal solidification kinetics from the standard parabolic TLP model was observed by increasing the bonding temperature to 1170 °C, which resulted in the formation of eutectic constituents at the joint centerline.The analysis of mechanical and fractographic test results revealed that the samples with complete isothermal solidification exhibit the highest shear strength, whereas the hard eutectic constituents act as preferential failure sites and lead to a significant reduction in the joint shear strength in samples with incomplete isothermal solidification.
基金support provided by the National Program on Key Basic Research Project of China (No. 2006CB601201)supports from the Research Fund for Doctoral Program of Higher Education of China (No. 200802941010)+1 种基金the Natural Science Foundation of Hohai University (No. 2008428011)the Scientific Research Startup Fund of Hohai University(No. 2084140801109)
文摘The open-cell Al foam core sandwiches（AFCSs） were successfully fabricated by using a specially designed Zn-Al-Cu based filler alloy via vibration aided liquid phase bonding method.The effects of the vibration on the bonding seam were investigated and the bonding strength between Al foam core and solid Al alloy face sheet was tested by shearing tests.The results show that vibration can significantly improve the quality of the bonding and the shearing strength of the bonding seam,which implies that this joining method has a good potential in practical applications.
文摘Transient liquid phase bonding of two dissimilar alloys Al 2024 and Ti?6Al?4V using Cu?22%Zn interlayer was carried out at 510 °C under vacuum of 0.01 Pa for various bonding time. In order to characterize the microstructure evolution in the joint zone, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were applied. The results show that joint formation is attributed to the solid-state diffusion of Cu and Zn into Ti?6Al?4V and Al 2024 alloys followed by eutectic formation and isothermal solidification along the Cu?Zn/Al 2024 interface. The hardness of the joints at the interface increases with an increase in bonding time which can be attributed to formation of intermetallic compounds such as Al2Cu, TiCu3, Al4.2Cu3.2Zn0.7, Al0.71Zn0.29, Ti2Cu, TiAl3 and TiZn16 in the joint zone. Moreover, shear strength of the joint reaches the highest value of 37 MPa at bonding time of 60 min.
基金supported by the fund of Natural Science Basic Research Program of Shaanxi(Grant No.2020JQ-190)National Natural Science Foundations of China(Grant Nos.51975480,52075449,and U1737205)China Postdoctoral Science Foundation funded project(Grant Nos.2019TQ0263,and 2020M683560)。
文摘This study focuses on the transient liquid phase(TLP)bonding of DD5 single-crystal superalloy to Cr Co Nibased medium-entropy alloy(MEA)using a BNi-2 filler alloy.The microstructure and mechanical properties of the TLP-bonded DD5/MEA joint were evaluated,and the microstructural evolution mechanism was investigated.The formation of the isothermal solidification zone(ISZ)depended on the diffusion of the melting-point depressants(Si and B elements)from the liquid filler into the DD5 and MEA substrates,as well as the dissolution of the substrates.Boron diffused along theγchannel of DD5 and reacted to form M_(5)B_(3)boride,herein referred to as the diffusion-affected zone(DAZ I).Similarly,the Cr_(5)B_(3)boride precipitated in the Ni-rich MEA matrix adjacent to the MEA substrate(i.e.,DAZ II).Additionally,a coherent orientation of[0]_(BCY)//[011]_(FCC)and(002)_(BCY)//(200)_(FCC)was detected between M_(5)B_(3)boride with a body-centered tetragonal(BCT)structure and the face-centered cubic(FCC)matrix.The performance of the joint was dominated by the properties of the bonding seam.As the bonding time increased from 20to 80 min,the athermal solidification zone(including eutectic microstructure)was gradually replaced by the ISZ exhibiting excellent plastic deformation capability,and the shear strength of the joint was improved.The maximum shear strength(752 MPa)was achieved when the eutectic-free joint was bonded at 1050℃ for 80 min.The fracture morphology revealed a mixture mode,indicating the initiation of cracks in the DAZ II,mainly propagating in the ISZ,and passing through the DAZ I.
文摘The transient liquid phase(TLP)bonding of CoCuFeMnNi high entropy alloy(HEA)was studied.The TLP bonding was performed using AWS BNi-2 interlayer at 1050℃ with the TLP bonding time of 20,60,180 and 240 min.The effect of bonding time on the joint microstructure was characterized by SEM and EDS.Microstructural results confirmed that complete isothermal solidification occurred approximately at 240 min of bonding time.For samples bonded at 20,60 and 180 min,athermal solidification zone was formed in the bonding area which included Cr-rich boride and Mn3Si intermetallic compound.For all samples,theγsolid solution was formed in the isothermal solidification zone of the bonding zone.To evaluate the effect of TLP bonding time on mechanical properties of joints,the shear strength and micro-hardness of joints were measured.The results indicated a decrement of micro-hardness in the bonding zone and an increment of micro-hardness in the adjacent zone of joints.The minimum and maximum values of shear strength were 100 and 180 MPa for joints with the bonding time of 20 and 240 min,respectively.
基金This work was financially supported by the Light Metal Educa-tional Foundation,Inc.of Japan.
文摘This work has successfully proposed a solution to produce robust Nb-interlayer-inserted Ti-6Al-4V/Si_(3)N_(4)joints optimized for a maximum operating temperature of 873 K;transient liquid phase bonding(TLPB)of Ti-6Al-4V/Nb side was carried out with Cu and Ni fillers to suppress brittle intermetallic compounds(IMCs),whereas brazing of Nb/Si_(3)N_(4)side was performed using a highly ductile Ti-added Ag-rich filler for effective residual-stress relaxation.A sound yet simple one-step bonding process incorporating simul-taneous TLPB and brazing was achieved with a relatively short holding time of 10 min at 1213 K.TLPB of Ti-6Al-4V/Nb side with Cu and Ni foils of 2-μm-thick each as a laminated filler suppressed brittle Ti-based IMCs and developed a homogenized microstructure consisting mainly of(α+β)-Ti via isothermal solidification.Meanwhile,brazing of Nb/Si_(3)N_(4)side with 100-μm-thick SILVER-ABA filler(92.75Ag-5Cu-1Al-1.25Ti mass%)foil enhanced interfacial bonding with sufficient total Ti content and accommodated residual stress better than conventional eutectic Ag-Cu-based fillers,and it was verified by finite element analysis with consideration of materials’temperature-dependent elasto-plastic properties.All joints with a bonding area of 10 mm×10 mm were tested via symmetrical four-point bending from room temper-ature(RT)to 873 K fractured from Nb/Si_(3)N_(4)side.When re-heating the joints from RT to 673 K,frac-ture initiation gradually shifted from Si_(3)N_(4)towards interfacial-compounds/Si_(3)N_(4)interface and bending strengths maintained∼220 MPa as weakening of SILVER-ABA filler was compensated by residual-stress relaxation in Si_(3)N_(4).When tested at 873 K,joints fractured mainly across the Ag-rich solid solution in a ductile manner and bending strength degraded by∼20%to 171 MPa as weakening of SILVER-ABA filler dominated.
文摘The effects of thermal cycle parameters on the tensile strength and fracture characteristics of phase transformation diffusion bonding(PTDB) joint of titanium and stainless steel (Ti/SS) were studied in this paper. With the maximum cyclic temperature of 1 173～1 223 K , the minimum cyclic temperature of 1 073～1 093 K , the heating velocity of 30～50 K/s , the cooling velocity of 15～20 K/s , the cycle numbers of 15～20 and bonding pressure is 13 MPa , the tensile strength of joint is more than 380 MPa , exceeding 80% of that of Ti.
基金supported by the Natural Science Foundation of Henan Province(Grant No.152107000047)
文摘In this study, a two-step heating process is introduced for transient liquid phase ( TLP) diffusion bonding fo r sound joints with T91 heat resistant steels. At first, a short-time higher temperature heating step is addressed to melt the interlayer, followed by the second step to complete isothermal solidification at a low temperature. The most critical feature of our new method is producing a non-planar interface at the T9/ heat resistant steels joint. We propose a transitional liquid phase bonding of T91 heat resistant steels by this approach. Since joint microstructures have been studied, we tested the tensile strength to assess joint mechanical property. The result indicates that the solidified bond may contain a primary solid-solution, similar composition to the parent metal and free from precipitates. Joint tensile strength of the joint is not lower than parent materials. Joint bend's strengths are enhanced due to the higher metal-to-metal junction producing a non-planar bond lines. Nevertheless, the traditional transient liquid phase diffusion bonding produces planar ones. Bonding parameters of new process are 1 260 °C for 0. 5 min and 1 230 °C fo r 4 min.
基金supported by the National Base Research Program of China
文摘Ni-base alloy DZ468 has been joined by transient liquid phase bonding technique with a newly developed Co-based filler. The microstructures of the Co-base filler and the joint, the effects of heat treatment on microstructure and hardness of the joint have been investigated by various experimental methods. Results show that the Co-base filler consists of γ, M2B, M5B3 and M23B6 phases. Because of the interdiffusion between the base metal and the filler, γ, MC, M5B3 and M23B6 phases are formed in the bonding zone. And localized liquidation of substrate occurs in the diffusion affected zone, with MC and M3B2 precipitating in this area. During heat treatment, the volume of the intermetallic phases in the bonding zone resulting from incomplete isothermal solidification decreases obviously. On the contrary, the width of the diffusion affected zone increases at the solution stage and subsequently decreases at the aging stages.
基金supported by the National MCF Energy R&D Program(No.2019YFE03100100)National Natural Science Foundation of China(NSFC,Nos.51975150,51974101,U21A20128,52175302,and 52105332)+2 种基金National Strategic International Science and Technology Innovation Cooperation Key Project(No.2020YFE0205304)Natural Science Foundation of Heilongjiang Province,China(Nos.JQ2020E003 and LH2020E037)Applied Basic Research Key Project of Yunnan(No.202002AB080001-1).
文摘Ductile transient liquid phase(TLP)bonding joints reinforced by multiple precipitates were produced using novel pre-sintered coatings and Au-Si fillers;therefore,the highest strength of NiTi/sapphire joints brazed at 460℃ for 30 min reached 72 MPa.The pre-sintering process improved the surface-active of sapphire by forming metastable Ti_(3)O and non-stoichiometric Al_(2)O_(3).The typical brazing seam consisted of O-rich compounds,TiSi_(2),and Ti-Ni-Si,wherein the O-rich phase featured different crystallinity depending on the oxygen content.The sapphire/seam interface was either a nanoscale diffusion region or a Si-rich amorphous layer.The breakdown of the Stokes-Einstein relation(SER)occurred,and the deviation from SER increased with a higher cooling rate.The influence of coating thickness was reflected in(i)the supercooling related to the viscosity and fractional exponent of liquids and(ii)the microstructural change of the joint related to the driving force for crystal growth.This work presented a new strategy for joining ceramics to metals at lower temperatures but using the joint at higher temperatures;furthermore,gave an insight into the microstructure evolution and kinetics behaviors based on supercooling in a transient liquid phase bonding joint.
文摘Microstructures and mechanical properties of transient liquid phase （TLP） bonded magnesium metal matrix composite （ MMC） joints using copper interlayer have been investigated. With an increase of bonding times from 5 min to 50 min at bonding temperature of 510 ℃ , the average concentration of copper in the bonded zone decreased, the microstructure in the zone changed from Cu, α-Mg and CuMg2 to α-Mg, CuMg2 and TiC, and mechanical properties of the joint increased. The shear strength of the joint bonded at 510 ℃ for 50 min reached 64 MPa due to the metallurgical bonding of the joint and improving its homogeneity of composition and microstructure. It is favorable to increase the bonding time for improving mechanical properties of TLP bonded magnesium MMC joint.
文摘High temperature oxidation behavior of two kinds of nitride bonded SiC based refractories wtls bwestigated at I 100-1 .500℃ by means of X-ray di[fractometer, scanning electronic microscopy and thermogravimetry. The results show that ： （1） with the temperature im＇reasing, the oxidation mass increment rote of the specimen increases.first and then. decreases, and oxidation passi＇va tion occttrs; （2） the oxidation resistance of SiAION bonded SiC refractories is superior to that of Si3N4 botlded SiC refractories ; （3） high temperature oxidtttion resuits itt the increase of compressive strength at room temperature of SiC based refractoviesiaes comlmred with specimen before oxidatiotl; the compressive strength of SIMON bonded SiC specimens oxidized at high temperatures decreases with the increase of the temperature as a result of formation amt burst of surfhce bubble, while the decrease of compressive strength of Sign4 bonded SiC specimens oxidized at high temperatures is owitng to the bwrease of the consistency of netlike crack assoeiated with cristobalite transfornuttion during cooling.
文摘Gaseous phases of carbon-containing and metastable oxides will be resulted from the carbonization of phenolic resin binders and the reduced reactions between C and oxides at high temperatures in carbon-containing refractories. With the in-situ catalysis technique, these gaseous phases can be transformed to one-or two-dimensional bonding phases by deposition,which is favorable for the improvement on strength and toughness of carboncontaining refractories,especially low carbon refractories. The research results reveal that：（ 1） the amorphous carbon resulted from phenolic resin can be transformed to carbon nanotubes,thus,the oxidation peak temperature is raised from 506 to 664. 6 ℃;（ 2） onedimensional whiskers of MgO or Mg Al2 O4 can be in-situ formed in MgO-C refractories, and their CMOR,CCS,rupture displacement and residual CCS（ two water quenching cycles,1 100 ℃） are increased by 66%,47%,13% and 26%,respectively;（ 3） two-dimensional array structure of flake β-SiAlON can be in-situ formed in Al2 O3-C refractories,which improves the material strength by 60% and decreases the residual strength after thermal shock by only 4. 5 MPa. It is believed that the in-situ formation of one-or two-dimensional bonding phases at high temperatures can improvethe comprehensive thermal physical properties of carboncontaining refractories,and will be the developing trend of the strengthening and toughening of low carbon-containing refractories.
文摘The influence of SiO2 on bonding phase fluidity was studied by measuring the projected area of tablets prepared using mixtures of fine iron ore and chemical reagents after sintering. The microstructure of samples was observed by optical microscope and SEM. Moreover, the relationship between SiO2 and bonding phase fluidity and microstructure was analyzed by CaO-Fe2O3-SiO2 system 1 300℃ isothermal section diagram. The main experimental conditions are as follows： in the composition of the bonding phase,CaO is 10%, 15% ,and 20%; SiO2 is 2% and 6% ; sintering temperature is 1 250, 1 300 and 1 350 ℃ ; the sample cooling rate is quick. The results of the study show that.① The fluidity of the binding phase decreases with the increase of SiO2 content. Moreover,fluidity increases as the sintering temperature increases; however, when the CaO content is 10% （relatively low proportion）, the lifting temperature has limited effect on fluidity improvement. ② The hematite proportion of the microstructure increases as the SiO2 content increases. ③ When SiO2 content increases, the solid phase ratio in the bonding phase grows,while the liquid phase ratio diminishes. Moreover the extension of the SiO2 content in the liquid phase is larger than that in the solid phase.
