Effect of holding time on microstructure and mechanical properties of Si3N4/Si3N4 joints brazed with Au58.7Ni36.5V4.8 filler alloy
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Si3N4 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 Si3N4 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 Si3N4 ceramic. In addition, Ni3Si intermetallic compound appears in the joint when the holding time increases to 90 min, resulting in the deterioration of the joint strength.
KeywordsFiller Metal Reaction Layer Joint Strength Standard Gibbs Energy Braze Alloy
This study was supported by the National Nature Science Foundation of China under the number of 50975064 and 51021002.
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