| The Ti-alloy has a lot of good functions,it is the material which is urgently needed in the professions such as aviation field,aerospace field and many other fields But its reserves is very limited and the price is expensive, these reasons limit its further generalization and application.Therefore, studying the conjunction of the Ti-alloy and the Cu-alloy is significative for using the Ti-alloy reasonablely,efficiently and fully and economizing the Ti-alloy resources .It also developsa new way to synthesize the good functions of the two alloys and improve the applicability of the correlative product. Diffusion bonding is a very important method in the field of different race material bonding. Its development breaks a newpath for the bonding of different race materials which are far different in characters,can't dissolve with each other or easy create brittleness intermetallic compound with each other, it's very fit for the conjunction of Ti and Cu.This text studied diffusion bonding of Ti-6Al-4V(TC4)and QAl10-3-1.5thoroughly and systematically.At first,we finished direct diffusion bonding (nonetransiTion layer),diffusion bonding which adding single transition layer (Ni,Cu...etc) and diffusion bonding which adding compound transition layer (Ni/Cu)respectively. To each kind of bonding,experiment many times by adjusting the main technical parameters of diffusion bonding(bonding temperature and bondingTime).After the experiments,measured tensile strength of the specimens and observeed interface structure, accordingly get the influence regulation of each maintechnical parameter to the bonding quality, confirm the best technical parametersof the diffusion bonding of each different transition layer;compare and analyse tensile strength of the joints in in each different transition layer thoroughly.According to result above, experiment again by the best technical parametersof each different transition layer. then use SEM,XRD and the other equipmentsto observe and analyse the diffusion condition of each main element,the sort,distribution , fashion theory of the microcosmic organization in diffusioninterface, analyse the influence of the microcosmic organization to the bondingquality;measure the microhardness changing conditions of the joints,study theinfluence of intermetallic compound forming in bonding interface tomicrohardness of the joints.and tensile strength changing conditions caused by it.The result of the experiments indicate: for all kinds of diffusion bonding ofTi-6Al-4V and QAl10-3-1.5 in the experiments(none transition layer,singletransition layer , compound transition layer), the main technicalparameters(bonding temperature,bonding time) have widespread and regular ontensile strength of the joints. First,tensile strength elevates along with the increaseof bonding temperature and bonding time gradually,but when it reach themaximum,it begins to descend as the increase of them.There is a best rangebetween the elevate segment and the descend segment,the best bondingtemperature range is 845℃-880℃, the best bonding time is 60min. The maximumtensile strength of none transition layer,Cu transition layer,Ni transitionlayer,Ni/Cu compound transition layer are: 179MPa,225MPa,325MPa,345MPa.It can be observed in the structure of rupture interfaces that though allkinds of the structures are differenet,they are almost frangible,only the structuresin the best technical parameters have some characteristic of tenacity.Along with the increase of bonding temperature and bonding time,the degreeof diffusion deepens obviously,there is many kinds of zonary intermetalliccompound created in the range near the interfaces of Ti-6Al-4V and QAl10-3-1.5or Ti-6Al-4V and the transition layers,and the quantity and density of theintermetallic compound increase gradually;there is no intermetallic compoundcreated in the interfaces of QAl10-3-1.5 and the transition layers,it is amicrocosmic boundary existing here all along.Through the XRD analysis and the Point-composition analysis,It can befound that: the rupture positions all locate at the intermetallic compound.Thecreated intermetallic compound in the interface of Ti-6Al-4V/QAl10-3-1.5 ismain Cu3Ti, the created intermetallic compound in the interface of Ti-6Al-4V/Cu/QAl10-3-1.5 is main CuTi3, the created intermetallic compound in theinterface of Ti-6Al-4V/Ni/QAl10-3-1.5 and the interface of Ti-6Al-4V/Ni/Cu/QAl10-3-1.5 both are main NiTi.According to the mensuration result of microhardness,the values ofmicrohardness elevate obviously in the range of intermetallic compounds, thecurve of microhardness value reachs its zenith,and descends when out of therange.The phenomenon shows adequately that:the intermetallic compounds arefrangible and rigid relative to experimental material,they reduce the strength ofthe joint and they are the main reason of rupture of the joint.Through all the studies above, diffusion bonding of Ti-6Al-4V and QAl10-3-1.5 by various transition layers is achieved successfully. The maximum tensilestrength of the joints gotten in the experiments exceeds 55% of the strength ofQAl10-3-1.5.These achievements offer constructive references for the diffusionbonding of the Ti-alloy and the Cu-alloy ,and enriched the related theories andpractice of diffusion bonding between different race materials.
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