The Effect of Bonding Time on Dissimilar Joint Properties Between Inconel 625 and AISI 316L Using Transient Liquid Phase Bonding Method with Cu Interlayer

In this paper, the effect of bonding time on the microstructural and mechanical properties of a dissimilar joint between Inconel 625 and AISI 316L was investigated using a Cu interlayer. For this purpose, the bonding was performed at the bonding temperature of 1100 °C for 15, 30 and 60 minutes. Field emission scanning electron microscope equipped with energy-dispersive x-ray spectroscopy was used for microstructural analysis. X-ray diffraction was used to identify the formed phases in the different zones of joint bonding. Shear strength and hardness tests were performed to evaluate the mechanical properties of the joints. Microstructural observations showed that the interface of Inconel 625 with the Cu interlayer contained Mo- and Nb-rich MC type carbide. Also, microstructural investigations showed that the bonding zone contains (Ni, Cr, Fe)-rich nanosized deposits in the Cu matrix. The specimen bonded at 1100 °C for 30 minutes demonstrated the maximum shear strength of 470 MPa, and its fractography dominantly showed a ductile dimple fracture. The isothermal solidification of Cu showed that the TLP bonding is controlled by both the diffusion kinetics and diffusion thermodynamics in the solidification of Cu. The asymmetric diffusion of Cu into the base metals caused the bonding interface shifts to 316L side.