Interface microstructure and strength of SiC/SiC joint brazed with CuTi alloys

Abstract

The joining of SiC to SiC was performed using amorphous CuTi filler metals with the Ti content ranging from 34 to 57 at%. The strength of joint was measured by fracture shear loading, and the joining mechanism was clarified by observing the microstructure and analyzing reaction phases in the joining layer. The fracture shear testing of SiC joints was carried out at elevated temperatures up to 973 K. The joining strength of SiC using Cu 66 Ti 34 filler is higher than that of SiC using other CuTi fillers at any brazing temperature at constant brazing times of 1.8 and 3.6 ks. The joining strength of the SiC joint decreases with increasing Ti content of the filler at constant brazing conditions. The Ti in CuTi alloys reacts with SiC, and forms TiC, Ti 3SiC 2 carbides and TiSi 2 suicides in the joining layer. For the SiC joint brazed with Ti-rich fillers, the excess amounts of reaction phases in the joining layer degrade the strength of the joints.