Microstructure and mechanical properties of brazed In718/SiC joints with AgCuTi/Cu foam/AgCuTi composite filler

Abstract

The connection of high temperature ceramics and alloys can give full play to their respective properties and obtain excellent composite structural components. A AgCuTi/Cu foam/AgCuTi composite filler is used to braze the Inconel 718 (In718) nickel-based superalloy and SiC ceramic in a vacuum furnace in this study. The influence of different brazing temperatures on the microstructure, phase composition and shear properties of the brazed joint is discussed. The microstructure is characterized by SEM and the phase composition was analyzed by EDS. Results show that the metallurgical bonding of the brazed joint is achieved at different temperatures. The interfacial phases formed at the brazed joint are mainly TiC, TiC + Ti5Si3 + Ni2Si, Cu (s, s), Ag (s, s) and TiC + TiNi3. The microstructure evolution mechanism of brazing joint products is revealed. The maximum shear strength of the brazed joint is 43 MPa, which is achieved at 900 °C for 15 min. The fracture mode of the brazed joints at the different brazing temperatures is brittle fracture. This work provides a method for the preparation of complex ceramic/metal components used in high-temperature environment.

Keywords

• In718 superalloy
• SiC ceramic
• Vacuum brazing
• Microstructure
• Shearing strength