保温时间对瞬时液相扩散连接的Ti_(3)Al/Ti_(2)AlNb接头微观结构及力学性能的影响

Effects of Bonding Time on Microstructure and Mechanical Properties of Ti_(3)Al/Ti_(2)AlNb Joint Prepared by Transient Liquid Phase Diffusion Bonding

采用Ni-Ti复合箔片作为中间层,在990℃、低连接压力(0.1 MPa)下,通过瞬时液相(TLP)扩散连接制备了Ti_(3)Al/Ti_(2)AlNb异种合金接头。分析了保温时间(10~90 min)对Ti_(3)Al/Ti_(2)AlNb接头微观结构及力学性能的影响,并研究了TLP扩散连接接头的界面演变和形成机制。结果表明,Ti_(3)Al/Ti_(2)AlNb接头具有典型的“Ti_(3)Al|Al_(0.5)Nb_(0.5)Ti_(3)|残余Ni|NiTi|NiTi_(2)|残余Ti|Al_(0.5)Nb_(0.5)Ti_(3)|Ti_(2)AlNb”多层梯度结构。随着保温时间的延长,接头的抗剪切强度先增大后减小,当保温时间达到60 min时,Ti_(3)Al/Ti_(2)AlNb接头的抗剪切强度最大,达到167±12 MPa。另外,接头的断裂主要发生在Ti_(2)AlNb/Ti附近的NiTi_(2)层,并向Ti层延伸,呈现出脆性断裂的特征。

Using Ni-Ti duplex foils as joining materials, Ti_(3)Al alloy was bonded to Ti_(2)AlNb alloy by transient liquid phase(TLP) diffusion bonding at 990 ℃ under low bonding pressure(0.1 MPa). The effects of bonding time on the microstructure and mechanical properties of Ti_(3)Al/Ti_(2)AlNb joint were analyzed, as well as the interfacial evolution and forming mechanism of the TLP joint were studied. Results show that the Ti_(3)Al/Ti_(2)AlNb alloy joints with typical interface structure of Ti_(3)Al | Al_(0.5)Nb_(0.5)Ti_(3)| residual Ni | NiTi | NiTi_(2)| residual Ti | Al_(0.5)Nb_(0.5)Ti_(3)| Ti_(2)AlNb can be formed. In addition, with the extension of bonding time, the shear strength of the joint first increases and then decreases, and the maximum shear strength, up to 167±12 MPa, of the Ti_(3)Al/Ti_(2)AlNb alloy joint can be achieved when the bonding time reaches 60 min. The joint fracture, characterized by brittle fracture, mainly occurs at the NiTi_(2)layer adjacent to the Ti_(2)AlNb/Ti interlayer and extends to the Ti interlayer.