Characterization of microstructure and mechanical properties of dissimilar TLP bonding between IN718/IN600 with BNi-2 interlayer

Abstract

The effect of bonding parameters on microstructure and mechanical properties of transient liquid phase joints of Inconel 600/BNi-2/Inconel 718 systems were investigated. Joining processes were carried out at 1050°C and 1100°C for 5–45min to achieve a joint free of intermetallic compounds. The results revealed that the a-thermally solidification zone was wider for short bonding times and lower temperature. B-Ni, B-Cr, B-Ni-Si, and Ni3Si phases were formed in the a-thermally solidification zone. The composition and morphology of compounds were different in diffusion affected zone of Inconel 718 and Inconel 600 superalloys. Carbo-boride phases were observed in the diffusion affected zone of Inconel 718 superalloy due to reducing the carbon solubility in the nickel alloy by diffusion of boron. Beside an intermetallic-free joint centerline was achieved at 1050°C and 1100°C for 45min and 30min, respectively. After homogenizing treatment at 1180°C for 180min, the intermetallic phases were eliminated completely. Highest hardness value achieved in the a-thermally solidification zone (∼486HV) and diffusion affected zone (∼671HV) of Inconel 718 due to existence of the intermetallic compounds. In addition, the maximum bonding shear strength was obtained about 568MPa for the homogenized sample. The fracture analysis showed the eutectic compounds in the diffusion affected zone were the main factor of the failure in the bonded sample for short bonding time.