Interfacial microstructure and mechanical property of ZrC-SiC ceramic and TiAl joint brazed with Ag–Zr active filler metal

Abstract

Reliable brazing of ZrC-SiC ceramic and TiAl alloy was achieved using active Ag–Zr filler metal. During the brazing process, Ti and Al were dissolved into the filler metal, and TiC+(Ti,Zr)3SiC2 layer formed due to the reaction between the ZrC-SiC and Ti. Meanwhile, strong affinity of Ti, Al and Zr produced dispersive (Ti,Zr)(Al,Ag) in the brazing seam. The effect of Zr content and holding time on the microstructure and mechanical property of the joints was investigated. With the increase of Zr content, the formation of (Ti,Zr)(Al,Ag) phase was promoted and its volume became large. The consumption of Ti in (Ti,Zr)(Al,Ag) phase restrained the formation of TiC, decreasing the thickness of TiC layer. Excess Zr addition could induce large bulks of (Ti,Zr)(Al,Ag) and cracks in the brazing seam. The holding time mainly affected the distribution of Ti-Zr-Al-Ag phases in the brazing seam. The joint strength reached a maximum value of 65 MPa when the Zr content of the filler was 5 wt% and holding time was 5 min. The crack propagated in the ZrC-SiC ceramic substrate.