Effect of brazing temperature on interfacial microstructure and mechanical property of Ti60/AgCu/ZrO₂ joint

Reliable brazing of Ti60 alloy and ZrO₂ ceramic was successfully achieved using AgCu filler metal. The interfacial microstructure and reaction products of Ti60/AgCu/ZrO₂ joints brazed at different temperatures were investigated by the Scanning Electron Microscope (SEM), Energy Dispersive Spectrometer (EDS) and X-Ray Diffractometer (XRD). Results show that the typical interfacial microstructure of the Ti60/AgCu/ZrO₂ joint was Ti60 alloy/α-Ti+Ti₂Cu diffusion layer/TiCu+TiCu₂/Ag(s, s)+Cu(s, s)/Ti₃Cu₃O layer/TiO layer/ZrO₂ ceramic. With the increase of the brazing temperature, the thickness of the diffusion layer of α-Ti+Ti₂Cu, TiCu+TiCu₂ layers, Ti₃Cu₃O layer and TiO layer adjacent to the ZrO₂ ceramic increased gradually, and the granular Ti-Cu IMCs grew gradually, meanwhile the content of the Ag-based solid solution and Cu-based solid solution decreased. The shear test indicates that the joint brazed at 900℃ for 10 min exhibited the highest shear strength of 124.9 MPa tested at room temprature, and the joint tested at 500℃ and 600℃ exhibited the shear strength of 83.0 MPa and 30.2 MPa, respectively. Typical fracture analysis displays that the brazed joint tended to fracture at the interface between the ZrO₂ ceramic and the brazing seam, and in the brazing seam adjacent to the interface.