Effect of silver interlayer on transient liquid phase (TLP) bonding of Al۲۰۲۴ to Ti-۶Al-۴V joints

Transient liquid phase (TLP) bonding of two dissimilar alloys Al ۲۰۲۴ and Ti-۶Al-۴V was carried out at ۵۸۰ and ۶۰۰ °C for ۴۵ min bonding time using a ۳۰-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 Ag۲Al, Al۲Cu and Al۲CuMg along the Ag/Al۲۰۲۴ interface. Moreover, the interdiffusion of titanium and aluminum led to the formation of Al۳Ti intermetallic compounds. These types of intermetallics produced a metallurgical bond at Al ۲۰۲۴ interface. The study showed that the shear strength of the joint reaches a high value of ۱۷۶.۱۱ MPa obtained at the higher bonding temperature of ۶۰۰ °C. It was also observed that the sample failed away from the base metal.

Keywords:

Transient liquid phase , Aluminum , Silver foil , Shear strength , Bonding temperature