The bonding time effects on the transient liquid phase bonding of Inconel 718 using nickel-based sintered brazing preform

摘要

In recent times, sintered brazing preform is used in the TLP bonding applications as it only undergoes partial melting during bonding, thus preserving its designed geometries. In this paper, the effects of bonding time on the transient liquid phase bonding joint of Inconel 718 using a new nickel-based sintered brazing preform was investigated. The microstructure and mechanical properties of SBP joints before and after bonding for different time were investigated. The results show that the ultimate tensile bonding strength of the joint was improved from 120 MPa to 410 MPa with the bonding time increasing from 2 to 300 min, due to the corresponding reduction of porosity and Ni3B type borides in the bonded sintered brazing preform. However, the strength decreased from 410 MPa to 370 MPa after bonding for 600 min. This was attributed to the grain coarsening that weakened the joint. In addition, the grain growth of Ni matrix in the sintered brazing preform was greatly impeded and its growth rate was nearly constant for the periods of bonding time tested, which are attributed to the relatively homogenous distribution of borides and Si-enriched particles. Moreover, more precipitates formed in the precipitation layer with increasing bonding time.