Correlation between microstructure and mechanical properties of active brazed Cf/SiC composite joints using Ti-Zr-Be

Cf/SiC composites were successfully active brazed by Ti-Zr-Be filler foil. The microstructure of the brazed joints was investigated by auger electron spectroscopy (AES) and scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS). The phase structure was determined by X-ray diffraction (XRD). The mechanical property was measured by mechanical testing machine. The results indicate that the brazed joint consisted of TiC, Ti3SiC2, ZrC, Be2C, Be17Ti2 and Ti-based solid solution (β-Ti). TiC+Ti3SiC2/ZrC+Ti(Zr)-Si-C+Be2C reaction layers were formed near Cf/SiC composite side while the reaction layer of β-Ti+Be17Ti2+Ti(Zr)3SiC2 with a small amount of ZrC, TiSi2, Be2C particles was formed in the center of the joint. With the increase of the brazing temperature or holding time, the amount of β-Ti compound in the interlayer decreased gradually while the thickness of reaction layer increased gradually. When the brazing temperature was 1000 °C and the holding time was 15 min, the maximum room temperature shear strength of the brazed joint can be achieved, which was 136.63 MPa. The joints with the parameters of 950 °C/30 min, 1000 °C/15 min and 1050 °C/5 min could resist a pressure of 5 MPa at 1200 °C for 5 min