Dissimilar friction stir welding between 1060 aluminum alloy and annealed pure copper sheet with a thickness of 3 mm was investigated. Sound weld was obtained at a rotational speed of 1050 r/min and a welding speed of...Dissimilar friction stir welding between 1060 aluminum alloy and annealed pure copper sheet with a thickness of 3 mm was investigated. Sound weld was obtained at a rotational speed of 1050 r/min and a welding speed of 30 mm/min. Intercalation structure formed at the crown and Cu/weld nugget （WN） area promotes interracial diffusion and metallurgical bonding of aluminum and copper. However, corrosion morphology reveals the weak bonding mechanism of internal interface, which causes the joint failing across the interface with a brittle-ductile mixed fracture mode. The tensile strength of the joint is 148 MPa, which is higher than that of the aluminum matrix. Crystal defects and grain refinement by severely plastic deformation during friction stir welding facilitate short circuit diffusion and thus accelerate the formation of A14Cu9 and A12Cu intermetallic compounds （IMCs）. XRD results show that A14Cu9 is mainly in Cu/WN transition zone. The high dislocation density and formation of dislocation loops are the major reasons of hardness increase in the WN.展开更多
The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is...The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%,mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.展开更多
The repair welding of UNS C95700manganese?aluminum bronze plates was done using different filler metals.Themicrostructure and mechanical properties of welds were studied.The main microstructural constituents wereα,β...The repair welding of UNS C95700manganese?aluminum bronze plates was done using different filler metals.Themicrostructure and mechanical properties of welds were studied.The main microstructural constituents wereα,βandκphases withdifferent morphologies.The addition of manganese decreased the percentage ofαphase in the microstructure of weldments from80%(Mn-free weld)to57%(12.5%Mn weld,mass fraction).The morphology ofκphase was lamellar in high nickel specimens andit was changed to a globular morphology for high manganese welds.Although the application of high manganese filler metal yieldedthe higher tensile and bending strengths of weldment compared with the weld using high nickel filler material,the optimummechanical properties of repair welds were obtained using a non-alloy filler material(ERCuAl-A2)for the underlay and highmanganese filler metal(ERCuMnNiAl)for filling passes.This weld presented an increase of39%in tensile strength compared withthe base metal,and no cracking was observed after bending test.展开更多
Rapidly solidified Sn-9Zn-0.1Pr(/Nd) alloy foils were prepared by melt-spinning method. Through comparison, the effects of rapid solidification process and 0.1%Pr/Nd(mass fraction) addition on the microstructure, ther...Rapidly solidified Sn-9Zn-0.1Pr(/Nd) alloy foils were prepared by melt-spinning method. Through comparison, the effects of rapid solidification process and 0.1%Pr/Nd(mass fraction) addition on the microstructure, thermodynamic characteristic of Sn-9Zn solder alloy were analyzed. The tensile-shear tests were used to evaluate the mechanical properties of solder/Cu joints. The results show that the rapid solidification process can greatly refine the microstructure of Sn-9Zn-0.1Pr(/Nd) alloys. After rapid solidification, the effects of Pr/Nd addition on microstructure are depressed. The pasty range of the rapidly solidified Sn-Zn-RE solders is also reduced significantly. The mechanical properties of solder/Cu joints are obviously improved using the rapidly solidified Sn-9Zn-0.1Pr(/Nd) solder alloy, which results in the formation of uniform interface. The promotion effect of Nd addition in Sn-9Zn alloy on the interfacial reaction of solder/Cu joint is more remarkable than that of Pr.展开更多
Joining of dissimilar aluminium-copper is an emerging area of interest for both research and industry due to its complex nature.Friction stir welding was attempted to evaluate the joint strength without offset at the ...Joining of dissimilar aluminium-copper is an emerging area of interest for both research and industry due to its complex nature.Friction stir welding was attempted to evaluate the joint strength without offset at the butt line between AA6063 to HCP copper sheet under different combination of rotational speed of 800 and 1000 r/min and travel speed of 20 and 40 mm/min.Material flow was studied in detail for different combinations of parameters with optical microscopy and elemental mapping by energy dispersive X-ray spectroscopy（EDS）.The results were correlated with the microstructural characteristics and formation of intermetallics at the bond interface using microhardness test and X-ray diffraction（XRD） technique.Material flow clearly suggests that energy input at 800 r/min and 20 mm/min is sufficient to plasticize both the materials with formation of higher amount of thermodynamically stable and hard intermetallic phases Al4Cu9 and Al Cu4（slower cooling rate of 88 K/s） than that at 800 r/min and 40 mm/min（faster cooling rate of 154 K/s）,attributed maximum joint strength（~78.6% of aluminium base metal）.展开更多
Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool...Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed?plungedepth diagrams for effective joining of these materials were developed.Using a central composite design model,empirical relationswere developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three processparameters such as tool rotational speed,plunge depth and dwell time.The adequacy of the developed model was verified usingANOVA analysis at95%confidence level.Response surface methodology was used to optimize the developed model to maximizetensile strength and minimize interface hardness.A high tensile shear failure load value of3850N and low interface hardness valueof HV81was observed for joints made under optimum conditions,and validation experiments confirmed the high predictability ofthe developed model with error less than2%.The operating windows developed shall act as reference maps for future designengineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.展开更多
基金Project(20140204070GX) supported by the Key Science and Technology of Jilin Province,China
文摘Dissimilar friction stir welding between 1060 aluminum alloy and annealed pure copper sheet with a thickness of 3 mm was investigated. Sound weld was obtained at a rotational speed of 1050 r/min and a welding speed of 30 mm/min. Intercalation structure formed at the crown and Cu/weld nugget （WN） area promotes interracial diffusion and metallurgical bonding of aluminum and copper. However, corrosion morphology reveals the weak bonding mechanism of internal interface, which causes the joint failing across the interface with a brittle-ductile mixed fracture mode. The tensile strength of the joint is 148 MPa, which is higher than that of the aluminum matrix. Crystal defects and grain refinement by severely plastic deformation during friction stir welding facilitate short circuit diffusion and thus accelerate the formation of A14Cu9 and A12Cu intermetallic compounds （IMCs）. XRD results show that A14Cu9 is mainly in Cu/WN transition zone. The high dislocation density and formation of dislocation loops are the major reasons of hardness increase in the WN.
基金Project(06GK2002) supported by the Major Project of Hunan Provincial Science and Technology Development Strategy
文摘The formation and the growth of Cu-Sn intermetallic compound (IMC) layer at the interface between Sn-3.0Ag-0.5Cu-xCe solder and Cu substrate during soldering and aging were studied. The results show that Cu6Sn5 IMC is observed at the interface between solder and Cu substrate in all conditions. After aging for 120 h,the Cu3Sn IMC is then obtained. With increasing aging time,the scalloped Cu6Sn5 structure changes to a plate structure. The Cu3Sn film always forms with a relatively planar interface. By adding a small amount of the rare earth element Ce (only 0.1%,mass fraction) into the Sn-3.0Ag-0.5Cu solder alloy,the growth rate of the Cu-Sn IMC at the interface of solder alloy system is decreased. When the time exponent is approximately 0.5,the growth of the IMC layer is mainly controlled by a diffusion over the studied time range.
文摘The repair welding of UNS C95700manganese?aluminum bronze plates was done using different filler metals.Themicrostructure and mechanical properties of welds were studied.The main microstructural constituents wereα,βandκphases withdifferent morphologies.The addition of manganese decreased the percentage ofαphase in the microstructure of weldments from80%(Mn-free weld)to57%(12.5%Mn weld,mass fraction).The morphology ofκphase was lamellar in high nickel specimens andit was changed to a globular morphology for high manganese welds.Although the application of high manganese filler metal yieldedthe higher tensile and bending strengths of weldment compared with the weld using high nickel filler material,the optimummechanical properties of repair welds were obtained using a non-alloy filler material(ERCuAl-A2)for the underlay and highmanganese filler metal(ERCuMnNiAl)for filling passes.This weld presented an increase of39%in tensile strength compared withthe base metal,and no cracking was observed after bending test.
基金Project(50675234)supported by the National Natural Science Foundation of China
文摘Rapidly solidified Sn-9Zn-0.1Pr(/Nd) alloy foils were prepared by melt-spinning method. Through comparison, the effects of rapid solidification process and 0.1%Pr/Nd(mass fraction) addition on the microstructure, thermodynamic characteristic of Sn-9Zn solder alloy were analyzed. The tensile-shear tests were used to evaluate the mechanical properties of solder/Cu joints. The results show that the rapid solidification process can greatly refine the microstructure of Sn-9Zn-0.1Pr(/Nd) alloys. After rapid solidification, the effects of Pr/Nd addition on microstructure are depressed. The pasty range of the rapidly solidified Sn-Zn-RE solders is also reduced significantly. The mechanical properties of solder/Cu joints are obviously improved using the rapidly solidified Sn-9Zn-0.1Pr(/Nd) solder alloy, which results in the formation of uniform interface. The promotion effect of Nd addition in Sn-9Zn alloy on the interfacial reaction of solder/Cu joint is more remarkable than that of Pr.
文摘Joining of dissimilar aluminium-copper is an emerging area of interest for both research and industry due to its complex nature.Friction stir welding was attempted to evaluate the joint strength without offset at the butt line between AA6063 to HCP copper sheet under different combination of rotational speed of 800 and 1000 r/min and travel speed of 20 and 40 mm/min.Material flow was studied in detail for different combinations of parameters with optical microscopy and elemental mapping by energy dispersive X-ray spectroscopy（EDS）.The results were correlated with the microstructural characteristics and formation of intermetallics at the bond interface using microhardness test and X-ray diffraction（XRD） technique.Material flow clearly suggests that energy input at 800 r/min and 20 mm/min is sufficient to plasticize both the materials with formation of higher amount of thermodynamically stable and hard intermetallic phases Al4Cu9 and Al Cu4（slower cooling rate of 88 K/s） than that at 800 r/min and 40 mm/min（faster cooling rate of 154 K/s）,attributed maximum joint strength（~78.6% of aluminium base metal）.
文摘Friction stir spot welding technique was used to join dissimilar combinations of aluminium alloy(Al5052)with copperalloy(C27200)and friction stir spot welding windows such as tool rotational speed–dwell time and tool rotational speed?plungedepth diagrams for effective joining of these materials were developed.Using a central composite design model,empirical relationswere developed to predict the changes in tensile shear failure load values and interface hardness of the joints with three processparameters such as tool rotational speed,plunge depth and dwell time.The adequacy of the developed model was verified usingANOVA analysis at95%confidence level.Response surface methodology was used to optimize the developed model to maximizetensile strength and minimize interface hardness.A high tensile shear failure load value of3850N and low interface hardness valueof HV81was observed for joints made under optimum conditions,and validation experiments confirmed the high predictability ofthe developed model with error less than2%.The operating windows developed shall act as reference maps for future designengineers in choosing appropriate friction stir spot welding process parameter values to obtain good joints.
