【作者】 郭伟；

【导师】 赵熹华；

【作者基本信息】 吉林大学 ， 材料加工工程， 2006， 博士

【摘要】 扩散连接是压力焊重要方法之一,广泛应用于航空航天等国防领域,新材料和异种材料的连接始终是该领域研究的前沿和热点。研究开发钛合金和其他材料的连接是充分开发钛合金优良特性,推广钛合金应用的有效途径。但是在理化性能相差较大的钛合金与铜合金扩散连接研究上却遇到很大困难,尤其是多元精密摩擦付类套筒结构件(先进战机航空发动机恒速装置)至今尚未获得成功。本文深入系统地研究了Ti-6Al-4V/QAl10-3-1.5直接或填加金属中间层的扩散连接工艺参数优化、接头界面组织结构以及对接头力学性能的影响等;提出了钛合金与铜合金套筒结构件膨胀压差法扩散连接新工艺,采用有限元方法模拟了Ti-6Al-4V环/QAl10-3-1.5柱套筒结构件膨胀压差法扩散连接时接头界面的应力应变以及焊后残余应力的分布规律,为膨胀压差法的工艺拟定提供依据,并通过工艺试验实现了Ti-6Al-4V环/QAl10-3-1.5柱套筒结构件的扩散连接。更多还原

【Abstract】 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<Cu<Ni<Ni/Cu under this article experiment range.Because interlayer Cu, Ni and Cu element of QAl10-3-1.5 is stable element ofβ_Ti, a layer of β_Ti is created near Ti-6Al-4V of jointsDifferential pressure expanded technique diffusion bonding is suitable tosleeve structure workpiece, the principle is that the diffusion pressure is producedby different coefficient of linear expansion of dissimilar metal, and the technicaldifficult point is making certain the relation of gap and diffusion pressure. Thedefinite element method is used to simulate the interface thermal stress and plasticfields when diffusion bonding of titanium alloy loop and copper pole sleevestructure is carried out. The result shows that the interface stress with 0-50μm gapcan satisfy requirement of bonding pressure only from the diffusion pressurefactor, and the relation between the gap and interface stress is linear. Transientsimulation shows that evident plastic deformed occurs on QAl10-3-1.5 under thecompressive stress, while no plastic deformed occurs to Ti-6Al-4V due to itshigher high temperature strengthAt the same time, the residual stress distribution of the joint is simulated, andresult shows that the radial stress on the interface is tensile stress.The press stress isnot varied on QAl10-3-1.5, and the stress value on the Ti-6Al-4V increases withthe increasing of radius. Mises residual stress distribution indicates that the biggestvalue of residual stress exists on the Ti-6Al-4V of outside of joint interface, whichdecreases with increasing radius.The technological test shows that Differential pressure expanded techniquediffusion bonding can realize the diffusion bonding of Ti-6Al-4V loop andQAl10-3-1.5 pole, and there are caves and microcrack on the interface of the jointthrough microstructure analysis.The isolation effectiveness of the diffusion bonding technology with metalisolation layer are studied, and the principles for the selecting crystalstructure,atomic radius and atomic electronegatedfor the layer are found by virtueof the bondibality of materials. The interface diffusion models of createing a solidsolution on interface with and without interlayers and that of sleeve structure areestablished which can been utilized to anlysis the element diffusionquantificationally.At last, the dynamics of element diffusion indicates that there is a latent periodin interface growth under the condition of no interlayer and Ni interlayer, andrelation between the thickness of intermetallics compound and diffusion timeconforms to parabola rule.更多还原