Low residual stress C/C composite-titanium alloy joints brazed by foam interlayer

Metallic foam was introduced as an interlayer to improve the performance of the brazed C/C composite-titanium alloy joint, and the interfacial microstructure and residual stress of the brazed joint were investigated. Compared with the brazed joint without foam, introducing foam interlayer could achieve the uniform bonding interface, and Ag-based solid solution (Ag(s,s)) became more dispersed and smaller in the center of the brazing seam. The thickness of reaction layer close to C/C composite side was less than 1 μm. Some Cu-based solid solution (Cu(s,s)) was detected, indicating that Cu foam still existed after brazing. The residual stress and its distribution calculated by finite element method (FEM), and the residual stress of the brazed joint decreased from 293 MPa to 228 MPa. The introduction of the foam interlayer could obtain homogeneous microstructure, change stress distribution, and improve mechanical properties of the brazed joints.