The effect of temperature on interface microstructure and shear strength of 1420 A1-Li alloy and 7B04 A1 alloy composite plates prepared by diffusion bonding were investigated. The results indicate the optimum tempera...The effect of temperature on interface microstructure and shear strength of 1420 A1-Li alloy and 7B04 A1 alloy composite plates prepared by diffusion bonding were investigated. The results indicate the optimum temperature for bonding the composite plates is 520℃, a sound bonding interface without continuous intermetallic compound layers and interfacial voids is obtained, and the shear strength value of bond joints can be as high as 190 MPa. An interfacial transition zone is formed due to the alloying elements mutual diffusion during the bonding process. Meanwhile, the effect of temperature on diffusion of alloying elements and interface reaction were discussed in detail, the results show that the higher temperature can increase the diffusion of alloying elements fluxes across the bonding interface, which can accelerate the closure of interfacial voids; meanwhile, when Mg atoms diffuse across the bonding interface, it can react with and break up the surface oxide films into discrete particles, and the removal of interface oxides increases the metal to metal bond areas and improves the bond quality.展开更多
In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding ...In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding processes.The melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu joints.However,diffusion bonding can be used to join these alloys without much difficulty.This work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar joints.The experiments were conducted using three-factor,five-level,central composite rotatable design matrix.Empirical relationships were developed to predict diffusion layer thickness,hardness and strength using response surface methodology.It is found that bonding temperature has predominant effect on bond characteristics.Joints fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.展开更多
Direct diffusion bonding of an orthorhombic Ti2AlNb base alloy to a TiAl base alloy, Ti-22Al-23Nb-2Ta and Ti-46.2Al-2Cr-2Nb-0.15B （at. pct）, was carried out and the interface microstructure, formation of new phase a...Direct diffusion bonding of an orthorhombic Ti2AlNb base alloy to a TiAl base alloy, Ti-22Al-23Nb-2Ta and Ti-46.2Al-2Cr-2Nb-0.15B （at. pct）, was carried out and the interface microstructure, formation of new phase at the interface and joint strength were characterized. At low temperature, a new phase with AlNb2-structure, Al（Nb, Ti）2, was formed in the interface region adjacent to the O base alloy. The α2 was found to be the major reaction product and developed in the interface region adjacent to the TiAl alloy as well as in the region adjacent to the O base alloy accompanying the formation of Al（Nb, Ti）2. The occurrence of Al（Nb, Ti）2 has been attributed to the different diffusivity of Nb and Al, leading to a eutectoid-like reaction. At relatively high temperature, Al（Nb, Ti）2 did not form due to enhanced diffusion of Nb but a B2-enriched zone formed on the O alloy side instead after long holding time. Only when an appropriate interface microstructure was achieved by optimizing the bonding parameters, could the shear strength of the joint reach 80% of that of the TiAl base alloy.展开更多
The Ti_(2)AlNb alloy was joined with TC4 alloy by vacuum diffusion bonding.The relationship between bonding parameters,and joint microstructure and shear strength was investigated.The results indicated that the diffus...The Ti_(2)AlNb alloy was joined with TC4 alloy by vacuum diffusion bonding.The relationship between bonding parameters,and joint microstructure and shear strength was investigated.The results indicated that the diffusion of Al,Ti,Nb and V elements across bonding interface led to the formation of three reaction layers:B2/βlayer andα2 layer on the TC4 side,andα2+B2/βlayer on the Ti_(2)AlNb side.The bonding temperature determined the atomic activity,thus controlling the growth of reaction layers and influencing the shear strength of the joint.When the Ti_(2)AlNb alloy and TC4 alloy were bonded at 950℃for 30 min under 10 MPa,the shear strength of the joint reached the maximum of 467 MPa.The analysis on the fracture morphology showed that the fracture occurred within the B2/βlayer and the fracture model was ductile rupture.Meanwhile,the formation mechanism of the Ti_(2)AlNb/TC4 joint was discussed in depth.展开更多
The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount ...The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount of voids decreases after increasing to the maximum value with the increasing bonding time. The irregular void with a scraggly edge tends to an ellipse void with smooth surface and then changes to a tiny void with round shape. The grains across bonding interface occur at bonding time of 60 min. The shear strength of bond increases with increasing bonding time, and the highest shear strength of bond is 887.4 MPa at 60 min. The contribution of plastic deformation on the void closure and the increase of shear strength is significant even though the action time of plastic deformation is short.展开更多
The atom (Ag,Cu) diffusion behavior and the effect of technology on the interface of rolled Ag/Cu composite contact were investigated. The concentration of Ag and Cu atoms near the interface was determined with electr...The atom (Ag,Cu) diffusion behavior and the effect of technology on the interface of rolled Ag/Cu composite contact were investigated. The concentration of Ag and Cu atoms near the interface was determined with electron probe. The bonding strength of composite interface was tested and the fracture in tensile sample was observed by SEM. The results show that there was inter diffusion of Ag and Cu atoms on the interface, which formed compact layer with high bonding strength of 98 MPa. The practical application proved that the Ag/Cu composite interface is reliable.展开更多
The interfacial reactions in partial transient liquid-phase bonding of Si3N4 ceramics with Ti/Ni/Ti interlayers were studied by means of scanning electron microscopy （SEM）, energy dispersive spectrometry （EDS） and...The interfacial reactions in partial transient liquid-phase bonding of Si3N4 ceramics with Ti/Ni/Ti interlayers were studied by means of scanning electron microscopy （SEM）, energy dispersive spectrometry （EDS） and X-ray diffractometry （XRD）. It was shown that the interfacial structure of Si3N4/TiN/Ti5Si3+Ti5Si4 + Ni3Si/ （NiTi ） /Ni3Ti/ Ni was formed after bonding. The activation energies for TiN layer and the mixed reaction layer of Ti5Si3 + Ti5Si4 + Ni3Si are 546. 8 kJ/mol and 543. 9 kJ/mol, respectively. The formation and transition processes of interface layer sequence in the joint were clarified by diffusion path. An important characteristic, which is different from the conventional brazing and soid-state diffusion bonding, has been found, i. e., during the partial transient liquid-phase bonding, not only the reaction layers which have formed grow, but also the diffusion path in the subsequent reaction changes because of the remarkable variation of the concentration on the metal side.展开更多
AA4045/AA3003 cladding billet was prepared by direct chill semi-continuous casting process. The macrostructures, microstructures, temperature distribution, compositions distribution and the mechanical properties at th...AA4045/AA3003 cladding billet was prepared by direct chill semi-continuous casting process. The macrostructures, microstructures, temperature distribution, compositions distribution and the mechanical properties at the bonding interface were investigated in detail. The results show that the cladding billet with few defects could be obtained by semi-continuous casting process. At the interface, diffusion layer of about 10μm on average formed between the two alloys due to the diffusion of alloy elements in the temperature range from 596 to 632 °C. From the side of AA4045 to the side of AA3003, the Si content has a trend to decrease, while the Mn content has a trend to increase gradually. Tensile strength of the cladding billet reaches 103.7 MPa, the fractured position is located on the AA3003 side, and the shearing strength is 91.1 MPa, revealing that the two alloys were combined metallurgically by mutual diffusion of alloy elements.展开更多
Diffusion bonding of as-cast Mg−6Gd−3Y magnesium alloy was carried out at temperatures of 400−480℃ with bonding pressure of 6 MPa for 90 min.Diffusion bonded joints were solution treated at 495℃ for 14 h and then ag...Diffusion bonding of as-cast Mg−6Gd−3Y magnesium alloy was carried out at temperatures of 400−480℃ with bonding pressure of 6 MPa for 90 min.Diffusion bonded joints were solution treated at 495℃ for 14 h and then aged at 200℃ for 30 h.Microstructures and mechanical properties of joints were analyzed.The results showed that rare earth elements and their compounds gathering at bonding interface hindered the grain boundary migration crossing bonding interface.Tensile strength of as-bonded and as-solution treated joints increased firstly and then decreased with the bonding temperature increasing due to the combined effects of grain coarsening and solid-solution strengthening.As-bonded and solution-treated joints fractured at matrix except the joint bonded at 400℃,while aged joints fractured at bonding interface.The highest ultimate tensile strength of 279 MPa with elongation of 2.8%was found in joint bonded at 440℃ with solution treatment followed by aging treatment.展开更多
Cu/Al clad strips are prepared using solid?liquid cast-rolling bonding(SLCRB)technique with a d160mm×150mm twin-roll experimental caster.The extent of interfacial reactions,composition of the reaction products,an...Cu/Al clad strips are prepared using solid?liquid cast-rolling bonding(SLCRB)technique with a d160mm×150mm twin-roll experimental caster.The extent of interfacial reactions,composition of the reaction products,and their micro-morphology evolution in the SLCRB process are investigated with scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD).In the casting pool,initial aluminized coating is first generated on the copper strip surface,with the diffusion layer mainly consisting ofα(Al)+CuAl2and growing at high temperatures,with the maximum thickness of10μm.After sequent rolling below the kiss point,the diffusion layer is broken by severe elongation,which leads to an additional crack bond process with a fresh interface of virgin base metal.The average thickness is reduced from10to5μm.The reaction products,CuAl2,CuAl,and Cu9Al4,are dispersed along the rolling direction.Peeling and bending test results indicate that the fracture occurs in the aluminum substrate,and the morphology is a dimple pattern.No crack or separation is found at the bonding interface after90°-180°bending.The presented method provides an economical way to fabricate Cu/Al clad strip directly.展开更多
The interfacial bonding of Ag-Cu (they are limited soluble) formed by the technology of cold pressure welding was discussed from the point of metallurgic view in this paper. Meanwhile, tensile test and microscopic tes...The interfacial bonding of Ag-Cu (they are limited soluble) formed by the technology of cold pressure welding was discussed from the point of metallurgic view in this paper. Meanwhile, tensile test and microscopic test were adopted for studying the state of interfacial bonding, suggesting that the joint of Ag-Cu has not only strong welding joint but also atomic diffusion on the interface. For Ag-Cu, the interaction of dislocation caused by plastic deformation will cause the strain and the vibration of microconstructer defects, accompanied by emitting energy. The energy increases the atomic action and the amplitude of atomic vibration, and the result is that the atom can diffuse to several lattice parameters deep from interface to inner metals. Therefore, under the condition of chemical potential gradient, the special technique, cold pressure welding rather than basic requirements of diffusion should be taken into account. During the cold pressure welding, plastic deformation plays an important role for it causes the metals′ displacement, crystal defects, further activates the surface atoms. Finally, the fracture of atomic bonding leads to the atomic exchange and diffusion between the new metals′ surfaces.In other words the metals Ag,Cu can achieve solidate bonding by cold pressure welding accompanied by the atomic diffusion. Moreover, theoretical analysis and calculation on the basis of thermodynamics, crystallogy, so- lid physics,etc, have been applied to calculate the amount of atomic diffusion, which has further proved the testing results that joint Ag-Cu has strong bonding strength through the mechanism of atomic diffusion.展开更多
In order to study the characteristics of deformation joining of aluminum-stainless steel composite sheet, an applied example of this composite sheet was given. The conditions of the composite sheet were discussed, the...In order to study the characteristics of deformation joining of aluminum-stainless steel composite sheet, an applied example of this composite sheet was given. The conditions of the composite sheet were discussed, the optical micrographs and scanning electron micrographs were examined by contrast ways of deformation joining and braze joining. Simultaneously the analysis of energy spectrum was also conducted. The results indicate that the deformation joining composite sheet possesses high bonding strength, good corrosion resistance, less inclusions and less microcracks.展开更多
基金financially supported by the Major State Basic Research Development Program of China(No.2011CB012803)the National Natural Science Foundation of China (No. 51334006)
文摘The effect of temperature on interface microstructure and shear strength of 1420 A1-Li alloy and 7B04 A1 alloy composite plates prepared by diffusion bonding were investigated. The results indicate the optimum temperature for bonding the composite plates is 520℃, a sound bonding interface without continuous intermetallic compound layers and interfacial voids is obtained, and the shear strength value of bond joints can be as high as 190 MPa. An interfacial transition zone is formed due to the alloying elements mutual diffusion during the bonding process. Meanwhile, the effect of temperature on diffusion of alloying elements and interface reaction were discussed in detail, the results show that the higher temperature can increase the diffusion of alloying elements fluxes across the bonding interface, which can accelerate the closure of interfacial voids; meanwhile, when Mg atoms diffuse across the bonding interface, it can react with and break up the surface oxide films into discrete particles, and the removal of interface oxides increases the metal to metal bond areas and improves the bond quality.
基金support rendered through a Major Research Project No. F-31-51/2005(SR)
文摘In many circumstances,dissimilar metals have to be bonded together and the resulting joint interfaces must typically sustain mechanical and/or electrical forces without failure,which is not possible by fusion welding processes.The melting points of magnesium(Mg)and copper(Cu)have a significant difference(nearly 400℃)and this may lead to a large difference in the microstructure and joint performance of Mg-Cu joints.However,diffusion bonding can be used to join these alloys without much difficulty.This work analyses the effect of parameters on diffusion layer thickness,hardness and strength of magnesium-copper dissimilar joints.The experiments were conducted using three-factor,five-level,central composite rotatable design matrix.Empirical relationships were developed to predict diffusion layer thickness,hardness and strength using response surface methodology.It is found that bonding temperature has predominant effect on bond characteristics.Joints fabricated at a bonding temperature of 450℃, bonding pressure of 12 MPa and bonding time of 30 min exhibited maximum shear strength and bonding strength of 66 and 81 MPa, respectively.
文摘Direct diffusion bonding of an orthorhombic Ti2AlNb base alloy to a TiAl base alloy, Ti-22Al-23Nb-2Ta and Ti-46.2Al-2Cr-2Nb-0.15B （at. pct）, was carried out and the interface microstructure, formation of new phase at the interface and joint strength were characterized. At low temperature, a new phase with AlNb2-structure, Al（Nb, Ti）2, was formed in the interface region adjacent to the O base alloy. The α2 was found to be the major reaction product and developed in the interface region adjacent to the TiAl alloy as well as in the region adjacent to the O base alloy accompanying the formation of Al（Nb, Ti）2. The occurrence of Al（Nb, Ti）2 has been attributed to the different diffusivity of Nb and Al, leading to a eutectoid-like reaction. At relatively high temperature, Al（Nb, Ti）2 did not form due to enhanced diffusion of Nb but a B2-enriched zone formed on the O alloy side instead after long holding time. Only when an appropriate interface microstructure was achieved by optimizing the bonding parameters, could the shear strength of the joint reach 80% of that of the TiAl base alloy.
基金This work was supported by the National Natural Science Foundation of China(No.51905055)the Natural Science Foundation of Chongqing,China(No.cstc2020jcyj-msxmX0115)the Fundamental Research Funds for the Central Universities,China(No.2020CDJ-LHZZ-086).
文摘The Ti_(2)AlNb alloy was joined with TC4 alloy by vacuum diffusion bonding.The relationship between bonding parameters,and joint microstructure and shear strength was investigated.The results indicated that the diffusion of Al,Ti,Nb and V elements across bonding interface led to the formation of three reaction layers:B2/βlayer andα2 layer on the TC4 side,andα2+B2/βlayer on the Ti_(2)AlNb side.The bonding temperature determined the atomic activity,thus controlling the growth of reaction layers and influencing the shear strength of the joint.When the Ti_(2)AlNb alloy and TC4 alloy were bonded at 950℃for 30 min under 10 MPa,the shear strength of the joint reached the maximum of 467 MPa.The analysis on the fracture morphology showed that the fracture occurred within the B2/βlayer and the fracture model was ductile rupture.Meanwhile,the formation mechanism of the Ti_(2)AlNb/TC4 joint was discussed in depth.
基金Project(51275416)supported by the National Natural Science Foundation of China
文摘The bonding interface characteristic and shear strength of diffusion bonded Ti-17 titanium alloy at different bonding time were investigated. The results show that the average size of voids decreases while the amount of voids decreases after increasing to the maximum value with the increasing bonding time. The irregular void with a scraggly edge tends to an ellipse void with smooth surface and then changes to a tiny void with round shape. The grains across bonding interface occur at bonding time of 60 min. The shear strength of bond increases with increasing bonding time, and the highest shear strength of bond is 887.4 MPa at 60 min. The contribution of plastic deformation on the void closure and the increase of shear strength is significant even though the action time of plastic deformation is short.
文摘The atom (Ag,Cu) diffusion behavior and the effect of technology on the interface of rolled Ag/Cu composite contact were investigated. The concentration of Ag and Cu atoms near the interface was determined with electron probe. The bonding strength of composite interface was tested and the fracture in tensile sample was observed by SEM. The results show that there was inter diffusion of Ag and Cu atoms on the interface, which formed compact layer with high bonding strength of 98 MPa. The practical application proved that the Ag/Cu composite interface is reliable.
文摘The interfacial reactions in partial transient liquid-phase bonding of Si3N4 ceramics with Ti/Ni/Ti interlayers were studied by means of scanning electron microscopy （SEM）, energy dispersive spectrometry （EDS） and X-ray diffractometry （XRD）. It was shown that the interfacial structure of Si3N4/TiN/Ti5Si3+Ti5Si4 + Ni3Si/ （NiTi ） /Ni3Ti/ Ni was formed after bonding. The activation energies for TiN layer and the mixed reaction layer of Ti5Si3 + Ti5Si4 + Ni3Si are 546. 8 kJ/mol and 543. 9 kJ/mol, respectively. The formation and transition processes of interface layer sequence in the joint were clarified by diffusion path. An important characteristic, which is different from the conventional brazing and soid-state diffusion bonding, has been found, i. e., during the partial transient liquid-phase bonding, not only the reaction layers which have formed grow, but also the diffusion path in the subsequent reaction changes because of the remarkable variation of the concentration on the metal side.
基金Project(2012CB723307)supported by the National Basic Research Program of ChinaProject(51204046)supported by the National Natural Science Foundation of ChinaProject(20130042130001)supported by the Doctoral Fund of Ministry of Education of China
文摘AA4045/AA3003 cladding billet was prepared by direct chill semi-continuous casting process. The macrostructures, microstructures, temperature distribution, compositions distribution and the mechanical properties at the bonding interface were investigated in detail. The results show that the cladding billet with few defects could be obtained by semi-continuous casting process. At the interface, diffusion layer of about 10μm on average formed between the two alloys due to the diffusion of alloy elements in the temperature range from 596 to 632 °C. From the side of AA4045 to the side of AA3003, the Si content has a trend to decrease, while the Mn content has a trend to increase gradually. Tensile strength of the cladding billet reaches 103.7 MPa, the fractured position is located on the AA3003 side, and the shearing strength is 91.1 MPa, revealing that the two alloys were combined metallurgically by mutual diffusion of alloy elements.
基金financially supported by the Science Innovation Foundation of Shanghai Academy of Spaceflight Technology,China (No.SAST2020-117)。
文摘Diffusion bonding of as-cast Mg−6Gd−3Y magnesium alloy was carried out at temperatures of 400−480℃ with bonding pressure of 6 MPa for 90 min.Diffusion bonded joints were solution treated at 495℃ for 14 h and then aged at 200℃ for 30 h.Microstructures and mechanical properties of joints were analyzed.The results showed that rare earth elements and their compounds gathering at bonding interface hindered the grain boundary migration crossing bonding interface.Tensile strength of as-bonded and as-solution treated joints increased firstly and then decreased with the bonding temperature increasing due to the combined effects of grain coarsening and solid-solution strengthening.As-bonded and solution-treated joints fractured at matrix except the joint bonded at 400℃,while aged joints fractured at bonding interface.The highest ultimate tensile strength of 279 MPa with elongation of 2.8%was found in joint bonded at 440℃ with solution treatment followed by aging treatment.
基金Project(51474189)supported by the National Natural Science Foundation of ChinaProject(QN2015214)supported by the Educational Commission of Hebei Province,China
文摘Cu/Al clad strips are prepared using solid?liquid cast-rolling bonding(SLCRB)technique with a d160mm×150mm twin-roll experimental caster.The extent of interfacial reactions,composition of the reaction products,and their micro-morphology evolution in the SLCRB process are investigated with scanning electron microscope(SEM),energy dispersive spectrometer(EDS),and X-ray diffraction(XRD).In the casting pool,initial aluminized coating is first generated on the copper strip surface,with the diffusion layer mainly consisting ofα(Al)+CuAl2and growing at high temperatures,with the maximum thickness of10μm.After sequent rolling below the kiss point,the diffusion layer is broken by severe elongation,which leads to an additional crack bond process with a fresh interface of virgin base metal.The average thickness is reduced from10to5μm.The reaction products,CuAl2,CuAl,and Cu9Al4,are dispersed along the rolling direction.Peeling and bending test results indicate that the fracture occurs in the aluminum substrate,and the morphology is a dimple pattern.No crack or separation is found at the bonding interface after90°-180°bending.The presented method provides an economical way to fabricate Cu/Al clad strip directly.
文摘The interfacial bonding of Ag-Cu (they are limited soluble) formed by the technology of cold pressure welding was discussed from the point of metallurgic view in this paper. Meanwhile, tensile test and microscopic test were adopted for studying the state of interfacial bonding, suggesting that the joint of Ag-Cu has not only strong welding joint but also atomic diffusion on the interface. For Ag-Cu, the interaction of dislocation caused by plastic deformation will cause the strain and the vibration of microconstructer defects, accompanied by emitting energy. The energy increases the atomic action and the amplitude of atomic vibration, and the result is that the atom can diffuse to several lattice parameters deep from interface to inner metals. Therefore, under the condition of chemical potential gradient, the special technique, cold pressure welding rather than basic requirements of diffusion should be taken into account. During the cold pressure welding, plastic deformation plays an important role for it causes the metals′ displacement, crystal defects, further activates the surface atoms. Finally, the fracture of atomic bonding leads to the atomic exchange and diffusion between the new metals′ surfaces.In other words the metals Ag,Cu can achieve solidate bonding by cold pressure welding accompanied by the atomic diffusion. Moreover, theoretical analysis and calculation on the basis of thermodynamics, crystallogy, so- lid physics,etc, have been applied to calculate the amount of atomic diffusion, which has further proved the testing results that joint Ag-Cu has strong bonding strength through the mechanism of atomic diffusion.
文摘In order to study the characteristics of deformation joining of aluminum-stainless steel composite sheet, an applied example of this composite sheet was given. The conditions of the composite sheet were discussed, the optical micrographs and scanning electron micrographs were examined by contrast ways of deformation joining and braze joining. Simultaneously the analysis of energy spectrum was also conducted. The results indicate that the deformation joining composite sheet possesses high bonding strength, good corrosion resistance, less inclusions and less microcracks.
