Effect of Bonding Temperature on Microstructure and Mechanical Properties of Zircaloy-4/Ti/Ag/304L Diffusion Bonded Joints

Abstract

Vacuum diffusion bonding of Zircaloy-4 (Zr-4) and 304L stainless steel by using pure Ti and pure Ag as multiple interlayers was carried out at the bonding temperatures of 800–900°C for the bonding time of 30 min under the bonding pressure of 12 MPa. The effect of the bonding temperature on the interfacial microstructure and mechanical properties of the joints was studied. The results showed that the interface zone of the joints was transited from 304L/Ag/α-Ag+TiAg/Ti/Ti(Zr)/Zr(Ti)/Zr-4 to 304L/Ag/α-Ag+TiAg/Ag(Ti, Zr)₂/Ti(Zr, Ag)/Ti(Zr)/Zr(Ti)/Zr-4 with the bonding temperature increased to 900°C while the TiAg content of α-Ag+TiAg layer decreased. Shear strength of the joints increased with the increasing of the bonding temperatures, and the maximum shear strength of 111.2 MPa was reached at 900°C. The fracture occurred in the Ag layer, which was mainly due to the low mechanical properties of Ag.

Fig. 1 The schematic diagram of the assemblies of 304L SS and Zr-4 using Ag and Ti as the multiple interlayers.