| Diffusion bonding is one of pressure welding, used wildly in national defensesfield such as navigation and spaceflight etc. The bonding of new materials anddissimilar is foreland and hot point in this field. It is effective way to extendtitanium application at large and that bonding of titanium and other materials isresearched and developed, but a certain difficult is encountered when titanium andcopper alloys with different physical chemical properties is bonded, especiallywhen sleeve structure such as complex precise friction pieces (constant speeddevice in advantaged fighter plane aero engine) is bonded, and it is failed to thisday. Diffusion bonding of Ti-6Al-4V/QAl10-3-1.5 with and without interlayer iscarried out, and the technological parameter optimized, interface structure of thejoint and the influence on mechanical properties for joint are studied deeply in thisarticle. The new technics named 'differential pressure expanded techniquediffusion bonding' is put forward used to bond titanium and copper alloy, Theinterface stressstrain field and residual stress distribution of joint is simulated usingfinite element method when Ti-6Al-4V/QAl10-3-1.5 sleeve structure is bonded,which offers the base for technics of differential pressure expanded techniquediffusion bonding, At last, the diffusion bonding of Ti-6Al-4V/QAl10-3-1.5 sleevestructure is carried out successfully.As an old and new type of press welding, Diffusion bonding is used wildly inmilitary, national defence, aviation and aerospace etc. fields. Titanium alloy andcopper alloy are two strategic metals of national economy, and it is very importantto study on their weldability. If the titanium alloy and copper alloy can beconnected together to fabricate a kind of sleeve structure plunger rotor used inaviation engine, which can has a wild application prospect in national aircraftmanufacture. Study on diffusion bonding of Ti-6Al-4V/QAl10-3-1.5 with nointerlayer or metal interlayers has been carried out in order to find out a kind ofoptimal diffusion bonding technics. The analyses of reaction product on theinterface of all kinds of joints provide theory foundation for interface reaction andgrown behavior mechanism of interface. The finite element method is used tosimulate the stress and plastic field and residual field on the interface of the jointswhen Ti-6Al-4V loop and QAl10-3-1.5 pole sleeve structure diffusion bonding isperformed by differential pressure expanded technique, which proves a basis forcraftwork design of differential pressure expanded technique. At last, TheTi-6Al-4V loop and QAl10-3-1.5 pole diffusion bonding has carried out throughtechnological tests. Through all of these aspects, several conclusions are achieved.Direct diffusion bonding of has been performed and the result indicates thatdiffusion bonding can bond Ti-6Al-4V and QAl10-3-1.5 together and Cu3Ti isproduced on the interface under the best technique condition of850℃/10MPa/60min, and lower tensile strength of 179MPa of joint is achieved.Fracture microstructure of the joints is analyzed, and fracture occurres on theintermetallics compound interlayer. When the diffusion temperature is 830-850℃,the fracture appearance is irregular strip or polyhedral grain, and the size ofintermetallics compound increases with the rise of temperature, yet when bondingtemperature ascends to 870℃, local melted phenomenon happens on the fracture,and the range of this phenomenon increases with the diffusion temperature, whichperhaps relates to the clustering of Al element.Diffusion bonding of Ti-6Al-4V/QAl10-3-1.5 with Cu interlayer is carried outand the tension strength of joint is a little better than that of direct joint under thebest technique condition of 850℃/10MPa/60min, The diffusion bonding joint iscomposed of Ti (ss.Cu),CuTi3 and Cu(ss.Ti) and the fracture appearance is mixedtype fracture on which not only running water shape brittle fracture figure but alsodimple plastic fracture figure has been found.Ni interlayer can increase evidently the tensile strength ofTi-6Al-4V/QAl10-3-1.5 diffusion bonding joint and The tensile strength of jointcan reach to 325MPa under the best technique condition of 870℃/10MPa/60min,which is 52% of QAl10-3-1.5. The tensile strength of Ti-6Al-4V/Ni/QAl10-3-1.5joint is depended on Ti-6Al-4V/Ni interface, and NiTi and Ni3Ti are found out onthe fracture interface of joint. The fracture mode is belong to brittle fracture andsmall and compact grains are shown on the fracture interface, and grains vary fromsmall and homogeneous strip to inhomogeneous size irregular polygonal grain withthe raise of diffusion temperature, and that the remelting phenomenon and secondgrown of grain occurs on local area.Diffusion bonding of Ti-6Al-4V/QAl10-3-1.5 with combined metal interlayerNi/Cu can utilize comprehensively both physical function of Cu and Ni, so that thetensile strength of joints increases greatly, which reaches 345MPa (55.2% ofQAl10-3-1.5.) under the best technique condition of 870℃/10MPa/60min. Thefacture occurs on the interface of Ti-6Al-4V/Ni. Because existence of interlayer Cucan improve the stress condition of joint, the tensile strength with Ni/Cu interlayeris a little bigger than that with only Ni interlayer, and the joint interface iscomposed of NiTi and CuTi3. The fracture mode is quasi-cleavage fracture, and thejoint has a little toughness.Study on diffusion bonding of Ti-6Al-4V/QAl10-3-1.5 with different kinds ofmetal interlayers reaches a conclusion that the joint performance varies from goodto bad is Ta |
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