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TiZrNiCu非晶钎料钎焊Ti60/Ti2AlNb 钛合金接头界面组织与性能

Interfacial microstructure and mechanical property of Ti60 and Ti2AlNb joint brazed with TiZrNiCu filler metal

    摘要
  • 摘要: 采用TiZrNiCu非晶钎料实现了Ti60和Ti2AlNb异种钛合金的真空钎焊连接，利用扫描电子显微镜（scanning electron microscope，SEM）、能谱仪（energy dispersive spectrometer，EDS）等方法分析了钎焊接头界面的显微组织，研究了钎焊温度对接头界面组织及力学性能的影响规律. 结果表明，钎焊接头的典型界面组织为Ti60/α + β/(Ti,Zr)2(Ni,Cu)/α + β/B2/β/Ti2AlNb；随钎焊温度的升高，(Ti,Zr)2(Ni,Cu)化合物含量减少且分布趋于均匀；较低的钎焊温度会导致钎缝中脆性化合物层过厚，易出现显微裂纹，成为接头的薄弱环节；过高的钎焊温度将导致Ti60母材侧出现粗大的片层状α + β组织；接头抗剪强度随钎焊温度升高呈现先增加后降低趋势，在980 ℃/10 min工艺条件下获得的接头平均抗剪强度达最大283.9 MPa. 断口分析表明，断裂均发生于钎缝处，均为脆性断裂.

     

    Abstract: The Ti60 titanium alloy was successfully vacuum brazed with Ti2AlNb titanium alloy by using TiZrNiCu filler metal. The interfacial microstructure and possible phases of the joints, as well as the fracture form of fractures, were detected by SEM and EDS. Effects of the brazing temperature on the interfacial microstructure and mechanical properties of the joints were investigated. The results show that the typical interfacial microstructure was Ti60/α + β/(Ti,Zr)2(Ni,Cu)/α + β/B2/β/Ti2AlNb. As the brazing temperature increased, the content of (Ti,Zr)2(Ni,Cu) phase decreased and they distributed more evenly. The lower brazing temperature caused the thick brittle layer, making it prone to microcracks and becoming a weak link in the joint. Besides, the lamellar α + β microstructure was formed when the brazing temperature was too high. With increasing of brazing temperature, shear strength of the joints was first increased and then decreased. The maximum shear strength of 283.9 MPa was obtained at the brazing temperature of 980 ℃ for 10min. Fracture analysis indicated that the joints were fractured at brazing seam, which performed as brittle fracture．

     

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