对TC4/QAL10-3-1.5直接扩散连接的研究表明:在连接温度T=850℃、连接压力P=8 MPa、保温时间t=30 m in的条件下,能够实现接头的扩散连接,然而在扩散接头的局部有裂纹产生。利用扫描电镜对扩散接头进行了显微组织分析,利用能谱仪对扩散接头的元素扩散距离和浓度分布进行了分析。结果表明:形成了厚度为10μm的扩散接头,元素扩散距离与保温时间之间满足抛物线规律x2=Kp(t-t0);由于Cu与Ti的扩散系数不同,导致发生扩散接头向TC4方向偏移的克肯达尔现象。利用界面孔洞理论解释了裂纹产生的机理,提出了工艺改进的方法,并获得了较好的效果。
The diffusion bonding was carried out to join Ti alloy(Ti-6Al-4V) and tin-bronze(ZQSn10-10) with Ni and Ni+Cu interlayer.The microstructures of the diffusion bonded joints were analyzed by scanning electron microscope(SEM),energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD).The results show that when the interlayer is Ni or Ni+Cu transition metals both could effectively prevent the diffusion between Ti and Cu and avoid the formation of the Cu-Ti intermetallic compounds(Cu3Ti,CuTi etc.).But the Ni-Ti intermetallic compounds(NiTi,Ni3Ti) are formed on the Ti-6Al-4V/Niinterface.When the interlayer is Ni,the optimum bonding parameters are 830℃/10 MPa/30min.And when the interlayer is Ni+Cu,the optimum bonding parameters are 850℃/10MPa/20min.With the optimum bonding parameters,the tensile strength of the joints with Ni and Ni+Cu interlayer both are 155.8MPa,which is 65 percent of the strength of ZQSn10-10 base metal.
The experimental investigation of the direct diffusion bonding of Ti-6Al-4V to ZQSn10-10 was carried out in vacuum. The microstructure of bonded joint was studied by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and the mechanical properties were detected by the tensile experiments. The microstructure and tensile strength of the joint mainly depend on the bonding temperature and bonding time. A satisfying diffusion bonded interface with a tensile strength of 73.9 MPa can be obtained under the condition of bonding temperature 850 ℃for 30 min. Three kinds of reaction products were observed in the bonded interface, namely β-Ti,Cu3Ti and CuSn3Ti5. And the brittle Cu3Ti and CuSn3Ti5 are mainly responsible for lowering the strength of the bonded joint. The diffusion distances of Sn, Cu and Ti and square root of bonding time are approximately linear relationship. And diffusion velocity of Sn, Cu and Ti in the diffusion reaction layer are 0.013 9,0.069 7 and 0.056 4 mm2/s.
