Microstructure and mechanical properties of Al2O3 ceramic and Ti6Al4V alloy joint brazed with inactive Ag–Cu and Ag–Cu + B

Abstract

Reliable brazing of Al2O3 ceramic and Ti6Al4V alloy was successfully achieved by using inactive Ag–Cu eutectic alloy and Ag–Cu+B composite filler. The effects of brazing temperature and B content on the interfacial microstructure and mechanical properties of the brazed joints were analyzed. The dissolution of active Ti element from Ti6Al4V alloy, which could be controlled by changing the brazing parameter, was the key factor to achieve a sound joint. TiB whiskers and Ti2Cu3 fine-particles were formed in the joint when the inactive Ag–Cu+B composite filler was used. The joint microstructure became fine and the thickness of Ti–Cu compound layer was reduced because of B additive. The maximum shear strength of 111MPa was obtained for the joint brazed with Ag–Cu+0.5wt.% B composite filler. The fracture modes were changed from a bowed crack path to a step-like one due to B additive.