Microstructure and Mechanical Characterization Study in the IN718/BNi-2/316L Joint by Transient Liquid Phase Bonding Process

In this research, the relationship among TLP bonding microstructures, mechanical properties and fracture mechanism of IN 718 / BNi-2 /AISI 316L joint was studied. In the first step, by changing TLP variables e.g. time and bonding temperature in the range 30-60 min and 950-1050 0 C respectively, characteristics of each type of microstructures including formation of destructive phases and homogeneity of microstructures were studied. In the second step, in order to investigate the mechanical properties and their fracture surface morphology, hardness and shear tests were accomplished. In the next stage, based on diffusion behavior of alloying elements, the relationship among microstructure, mechanical properties and fracture mechanism was studied. Results show that microstructures of bonding region were classified in three types. Type I: solid state bonding microstructure, Type II: Athermal – isothermal solidification microstructure, and Type III: isothermal solidification microstructure.