Transient liquid phase bonding of stainless steel 316 L to Ti-6Al-4 V using Cu/Ni multi-interlayer: microstructure, mechanical properties, and fractography

In the present work, transient liquid phase bonding (TLP) of stainless steel 316 L to Ti-6Al-4 V using simultaneously both Cu and Ni interlayers was performed and effect of bonding temperature (950 to 1050 °C) on microstructure and mechanical properties of the joints was studied. The joint zones were analyzed using scanning electron microscopy (SEM) equipped with energy dispersive spectroscopy (EDS). Microhardness and shear strength tests were also applied to evaluate the mechanical properties of the joints. The results showed that various eutectic phases and intermetallic compounds were formed at the interface; however, diversity of intermetallics was different in the joint zone for each specimen which can be due to the bonding temperature and type of eutectic phase transformation. The more increase of bonding temperature to higher than 1000 °C, the more deterioration in mechanical properties of the bonded joints is led so that the shear strength decreased from 385 MPa (maximum value) to 257 MPa.