Electrically assisted diffusion bonding of Ti₂AlNb alloy sheet using CP-Ti foil interlayer: Microstructural characterization and mechanical tests

This study presents an electrically assisted diffusion bonding (EADB) process as a variation of solid-state diffusion bonding to obtain a wider dissemination of this technique. This concept is an experimental adaptation inspired by the rapidly increasing Joule heat during welding that has already been placed into practice. EADB was studied for a Ti₂AlNb alloy sheet using a commercially pure titanium (CP-Ti) foil interlayer. An in-house built experimental setup was assembled to implement the EADB concept. The nonuniform temperature profiles of the Ti₂AlNb alloy sheets under different electric current densities were imaged for reference in the subsequent discussion. Common characterization techniques were used to observe the interfacial microstructures, and the shear property and surface Vickers hardness were tested to assess the joint quality. The results showed that bonding interfaces consisted of the interlayer zone and the transition zone, and the Ti₂AlNb alloy sheets were completely bonded under high electric current densities in the central zone of the sheet. When the density was increased to 4.58 A/mm², the average room-temperature shear strength and Vickers hardness value reached the maximum values of 641 MPa and 493 HV, respectively.