Mechanisms associated with material deformation, and microstructural evolution during friction stir welding of pure titanium and Al alloy

Aluminium and titanium are important structural metals; however, their joining is difficult because of different microstructural responses and intermetallic compounds (IMCs). The present work underlines the mechanisms associated with friction stir welding of pure Ti and Al alloy. The results show no visible defect, while multiple particles are consolidated in the stirred zone (SZ). Chemical composition across Al-Ti interfaces is different and dependent on location and particle size. This affirms intensive mechanical mixing and thermal diffusion of Al-Ti substrates and IMCs formation. The UTS and ductility of the Al-Ti joint are ∼73% and 37% higher than Al base metal, respectively. Deformation of Ti in SZ is responsible for phase evolution and joint formation with better joint characteristics.