Interface characteristic and mechanical performance of TiAl/Ti 2 AlNb diffusion bonding joint with pure Ti interlayer
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Interface characteristic and mechanical performance of TiAl/ Ti2AlNb diffusion bonding joint with pure Ti interlayer Lei Zhu, Bin Tang* , Ming-Xuan Ding, Yan Liu, Xiao-Fei Chen, Shao-Peng Yan, Jin-Shan Li
Received: 25 March 2020 / Revised: 17 May 2020 / Accepted: 21 July 2020 Ó The Nonferrous Metals Society of China and Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Solid-state diffusion bonding (DB) of TiAl alloy and Ti2AlNb alloy was carried out using pure Ti as an interlayer at 1000 °C under 20 MPa for 60–120 min. The effects of bonding times on the interfacial microstructure and mechanical performance of the TiAl/Ti/Ti2AlNb bonded joints at room temperature (RT) were investigated detailly. The results demonstrated that the diffusion layers (DLs) mainly consisted of four characteristic layers, (I) single coarse a2 phase adjacent TiAl alloy, (II) single refined a2 phase at the bonding interface, (III) equiaxed/ acicular a2 phase embedded in b phase adjacent Ti2AlNb alloy and (IV) both equiaxed a2 phase and acicular O phase embedded in b phase adjacent Ti2AlNb alloy, respectively. The thickness of the four layers increased with the increasing of the bonding time. The growth of DLs is controlled by diffusion and the reaction rate constant k for region I, II, III and IV are 1.22 9 10-6, 1.27 9 10-6, 2.6 9 10-7 and 7.7 9 10-7 ms-1/2, respectively. Meanwhile, the interface a2 grain grows up without texture. The maximum tensile strength of 281 MPa was maintained at 1000 °C for 90 min under the pressure of 20 MPa. Consequently, the phase transformation and dynamic recrystallization behavior of the DLs were discussed.
L. Zhu, B. Tang*, M.-X. Ding, Y. Liu, X.-F. Chen, S.-P. Yan, J.-S. Li State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China e-mail: [email protected] B. Tang, J.-S. Li Shaanxi Key Laboratory of High-Performance Precision Forming Technology and Equipment, Northwestern Polytechnical University, Xi’an 710072, China
Keywords Sputtering; Bonding interface; Microstructure; Growth kinetics; Mechanical performance
1 Introduction As one of pivotal high-temperature structure engineering material, TiAl-based alloy has been used in aerospace and auto industry for several years due to its attractive ‘‘strong and light’’ properties, such as excellent high-temperature strength, low density, good creep and outstanding oxidation resistance [1–7]. Nevertheless, it is regretful that the engineering application of TiAl-based alloy is also limited due to the intrinsic brittleness and poor hot workability [8, 9]. Therefore, it is necessary to using welding technology to expand the practical engineering application of TiAl-based alloy. In recent years, some melt weld methods have been applied to join the TiAl-based alloy [10–13]. Compared with the melt weld methods, vacuum solid-state diffusion bonding (DB) has been thought to be an appropriate way to fabricate TiAl-based alloy [14–17], which can avoid the micro-cracks
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