Abstract:The non-active AgCu filler metal was used to join Si3N4 ceramics to TiAl-based alloys. The typical interfacial microstructure of the joints was determined as TiAl/Ti3Al+Ti(s,s)/AlCuTi/Ag(s,s)+AlCu2Ti/Ti5Si3+TiN/Si3N4 ceramics. During the brazing process, the active element Ti, which dissolves into the non-active AgCu liquid filler metal, involves in the wetting on the Si3N4 ceramic and reacts to the ceramic materials. With the increase of brazing temperature and holding time, the thickness of the TiN reaction layer close to the Si3N4 ceramic increases and AlCu2Ti compounds dispersed in the Ag-based solid solution gather greatly, which reduces the joining properties. The shear strength of the joints reaches a maximum of 124.6 MPa when the brazing temperature T = 860 oC and the holding time t=5 min. According of the thermodynamics and kinetics calculation, the activation energy Q and the growth coefficient KP of the TiN layer are 528.7 kJ/mol and 2.7×10-7 m/s1/2, respectively