Strength and microstructure of diffusion bonded titanium using silver and copper interlayers

Commercially pure Ti has been diffusion bonded using silver and copper interlayers and without any interlayer. The microstructure of the bonded zone is affected by the bonding temperature, bonding time and interlayer type. With a silver (Ag) interlayer at 980°C for 10h, the diffusion zone consisted of a solid solution of Ag at the center and a zone of AgTi intermetallics on both sides of it. As the temperature and time increased (1030°C, 30h), AgTi with small amount of dispersed AgTi₂ formed at the center of the diffusion zone and next to it a eutectoid mixture of Ti solid solution and AgTi appeared. When Cu was used as an interlayer at 900°C for 10h, Cu-Ti solid solution, a zone of different intermetallics, and Ti-Cu solid solution formed in the bonded zone. However, at 1000°C or higher temperatures, no continuous zone of intermetallics was found in the bonded region, only eutectic mixtures and Ti-Cu solid solutions appeared. The maximum tensile strengths achieved were 160MPa, 502MPa, and 382MPa when Ag, Cu and no interlayers were used, respectively.