基于Zr-Ni-Cu-Ti-Zr中间层的Ti2AlNb/GH4099的原位反应钎焊接头显微组织和力学性能分析

Microstructure and Mechanical Properties of Ti2AlNb/GH4099 Joints Prepared by In-situ Synthesis Brazing Using Zr-Ni-Cu-Ti-Zr Interlayer

摘要:

采用Zr-Ni-Cu-Ti-Zr复合中间层进行了Ti₂AlNb合金和镍基高温合金GH4099原位反应真空钎焊连接，并观察了钎焊接头的界面组织及断口形貌，分析了接头界面组织的演变过程。结果表明，钎焊接头的典型界面组织为Ti₂AlNb/B2+O+ β(Ti,Nb)+α-Zr+Zr₂Ni+(Ti,Zr)₂(Cu,Ni)/(Ti,Zr)(Cu,Ni)/Ti₃Al+(Ni,Cr)_ss/GH4099。随着钎焊温度的升高，母材侧的反应层厚度增加，(Ti,Zr)₂(Cu,Ni)金属间化合物聚集在界面两侧形成连续相，钎缝和母材界面处萌生裂纹并扩展，导致接头强度下降。在920 ℃/15 min钎焊工艺参数下，所得接头的抗剪强度最大为171.87 MPa。接头断裂模式为脆性断裂，断口主要由(Ti,Zr)₂(Cu,Ni)和 (Ti,Zr)(Cu,Ni)脆性金属间化合物组成。

Abstract:

Vacuum brazing of Ti₂AlNb alloy to Ni-based superalloy GH4099 based on in-situ synthesis using Zr-Ni-Cu-Ti-Zr composite interlayer was carried out. The interfacial microstructure and fracture morphology of brazed joints were observed and the phase evolution mechanism of the joint was investigated. The results show that the typical interfacial microstructure of the joint is Ti₂AlNb/B2+O+β(Ti,Nb)+α-Zr+Zr₂Ni+(Ti,Zr)₂(Ni,Cu)/(Ti,Zr)(Ni,Cu)/Ti₃Al+(Ni,Cr)_ss/GH4099. With the increase in brazing temperature, the thickness of the reaction layer on the base material sides increases, (Ti,Zr)₂(Cu,Ni) intermetallic compounds aggregate to form continuous phases on both sides of the interface, and cracks grow and expand at the interface between the brazing seam and the substrate, resulting in the decrease in joint strength. The maximum shear strength of 171.87 MPa is obtained after brazing at 920 ℃ for 15 min. The fracture mode of the joint is cleavage fracture and the fracture mainly consists of brittle (Ti,Zr)₂(Cu,Ni) and (Ti,Zr)(Cu,Ni) intermetallic compounds.