Effect of holding time on microstructure and mechanical properties of Si_3N_4/Si_3N_4 joints brazed with Au58.7Ni36.5V4.8 filler alloy

摘要

Si_3N_4 ceramics were brazed using Au-Ni-V metal foils at 1423 K for different holding times. Effect of holding time on microstructure and mechanical properties of the joints was investigated. The results indicate that a reaction layer of VN exists at the interface between Si_3N _4 ceramic and filler alloy. With increasing holding time from 0 to 90 min, thickness of the VN reaction layer increases from 0.4 to 2.8 μm, obeying a linear relation. Mechanism of the interfacial reaction was discussed by calculating the formation of free energy of VN. No specific orientation relationship exists between VN reaction layer and Si_3N_4 ceramic. In addition, Ni_3Si intermetallic compound appears in the joint when the holding time increases to 90 min, resulting in the deterioration of the joint strength.