Transient Liquid Phase Bonding of Titanium Aluminide Alloys – A Microstructural Investigation

Abstract

Transient liquid phase (TLP) bonding [1] is widely used in the aerospace industry for both initial fabrication and pre-and post-service repairs. TLP bonding is derived from high-temperature brazing [2]. However, unlike conventional brazing, extensive diffusion of bond-line and/or substrate constituents is allowed to occur during bonding. This induces compositional changes at the bond-line, which in turn raise the melting temperature of the interlayer used to form the bond. Thus, TLP bonds undergo isothermal re-solidification at the bonding temperature. If a suitable post-isothermal-solidification homogenization treatment is applied, the remelt-temperature, microstructure and hence properties of TLP bonded components can match those of the parent materials. Given that TLP bonding is conducted under isothermal conditions, well below the melting temperature of the substrates and can reproduce parent-metal microstructures, this process is well suited to the joining of damage-sensitive materials, with carefully tailored microstructures, such as structural intermetallic compounds.

Effect of Bonding Temperature on Microstructure and Mechanical Properties of Dissimilar Joint Between Inconel 617 and Stainless Steel 310

“…The main advantage of TLP over conventional fusion welding is that it can produce joints with mechanical properties similar to those of the base metals [2,5]. In TLP joining, an interlayer is melted during bonding process and joining is accomplished upon subsequent inter-diffusion of alloying elements between the liquid and the base metals [6].…”