Effect of bonding temperature on microstructure and mechanical properties of TLP-bonded Ti-6Al-4V/Inconel 718 joints using BNi2/Cu interlayer

The joining of Ti-6Al-4 V to Inconel 718 is notable in industries. This research studied the effect of bonding temperatures (800, 850, 900, 950, and 1000 °C) on properties of Ti-6Al-4 V and Inconel 718 joints using BNi2/Cu interlayer in TLP bonding. The samples were analyzed for their microstructure and mechanical properties using a range of techniques: optical microscopy (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness testing, shear strength evaluation, and high-temperature shear tests. Microstructural analysis indicated the formation of intermetallic compounds like Ti2Cu, Ti₂Ni, NiTi, and Ni₃Ti within the diffusion-affected zone (DAZ) and solidification zone (SZ) of the TLP-bonded samples. The results demonstrated that temperature had a profound impact on the microstructure of the TLP-bonded samples; specifically, the width of the solidification zone increased as the TLP temperature rose. Moreover, there was an optimal temperature for achieving superior mechanical properties. For instance, a shear strength of 399.75 MPa was achieved at 950 °C as the highest shear strength value. The findings also revealed that both lower (800 °C) and higher (1000 °C) bonding temperatures led to decreased shear strength due to the presence of porosities and cracks. The high-temperature testing showed suitable mechanical properties for elevated temperatures.