Interfacial structure and properties of Si₃N₄ ceramic and TiAl alloys brazed with Ti/Ag-Cu/Cu interlayers

The Si₃N₄ ceramics was brazed to TiAl alloys with Ti/Ag-Cu/Cu as the interlays, and a good joint was obtained. The interfacial microstructure of the joint and the elements were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer distribution (EDS). The results show that the typical interfacial microstructure of Si₃N₄/Ti/Ag-Cu/Cu/TiAl may be Si₃N₄/TiN/Ti-Si/Cu-Ti+Ag(s,s)+Cu(s,s)/AlCuTi/TiAl. The influences of brazing temperature, holding time and the pressure of the joint on the four-point bending strength of the joint were researched by using controlling variables method. The four-point bending strength of the joint reaches the maximum of 170 MPa when the brazing temperature, holding time and the pressure of the joint are 1 133 K, 30 min and 0.040 MPa, respectively.