Effect of silver interlayer on transient liquid phase (TLP) bonding of Al2024 to Ti-6Al-4V joints

Abstract

Transient liquid phase (TLP) bonding of two dissimilar alloys Al 2024 and Ti-6Al-4V was carried out at 580 and 600 °C for 45 min bonding time using a 30-µm-thick pure silver (Ag) foil interlayer. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to investigate the phase structure and compositional changes across the joint region. Mechanical properties of the joints were investigated through shear strength and hardness tests. The joint formation was due to the solid-state diffusion of Ag and Cu into Al and Ti alloys, followed by eutectic formation, isothermal solidification, and formation of various intermetallic compounds such as Ag2Al, Al2Cu and Al2CuMg along the Ag/Al2024 interface. Moreover, the interdiffusion of titanium and aluminum led to the formation of Al3Ti intermetallic compounds. These types of intermetallics produced a metallurgical bond at Al 2024 interface. The study showed that the shear strength of the joint reaches a high value of 176.11 MPa obtained at the higher bonding temperature of 600 °C. It was also observed that the sample failed away from the base metal.