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

Abstract

The laser brazing was carried out for dissimilar joining of sialon to the WC-Co alloy using the eutectic type Ag-Cu alloy filler metal with different Ti contents ranging from 0 to 2.8 mass% in order to investigate the effects of Ti as an active element in the filler metal on the interface structure of the joint and the joint strength. The filler metal sheet was sandwiched by the sialon block and the WC-Co alloy plate. The laser heating was carried out by irradiating laser beam selectively on the WC-Co alloy plate. The brazed joint was obtained using the filler metal containing over 0.3 mass%Ti, which was joined through the interfacial compound layer consisted of TiN, Ti₅Si₃ and Cu₄Ti. The shear strength of the brazed joint increased with increasing Ti content in the filler metal in the range of 0.3 to 1.7 mass%, and reached 106 MPa in maximum value, but it decreased at a higher Ti content.