Effect of Ti content in Ag-Cu-Ti activated filler metal on dissimilar joint formation of sialon and WC-Co alloy by laser brazing

Laser brazing was carried out for dissimilar joining of sialon and a WC-Co alloy. Eutectic type Ag-Cu alloys as filler metals with different Ti content ranging from 0 to 2.8 mass-% were used to investigate the effects of Ti on the interface structure and strength of the joint. The filler metal sheet was sandwiched between a sialon block and a WC-Co alloy plate, and a laser beam was irradiated selectively on the WC-Co alloy plate. The brazed joint was obtained using the filler metal containing.0.3 mass-% Ti. TiN, Ti5Si3, and Cu4Ti layers were formed at the interface of sialon and brazed metal as compound layers. The shear strength of the brazed joint increased with increasing Ti content in the filler metal in the range 0.3-1.7 mass-%, reaching a maximum value of 106 MPa. However, the strength decreased when the Ti content became higher than 1? 7 mass-%.