Effect of Mechanical Mixing in Dissimilar Friction Stir Welding of Aluminum to Titanium with Zinc Interlayer

Welding of aluminum (Al) and titanium (Ti) is difficult and challenging due to their differences in chemical and physical properties, and the evolution of brittle intermetallic compounds. Formation of critical intermetallics can be minimized by using an interlayer material, which leads to ternary mechanical mixing in the weld nugget. In the present investigation, a zinc (Zn) interlayer has been used during friction stir welding (FSW) of Al�Ti. It has been found that tool offset position is one of the important parameters in controlling the amount of ternary mechanical mixing of materials. The mechanical mixing of Zn with Al and Ti alters the phase evolution and restricts the formation of the brittle Al 3 Ti intermetallic compound. The optimum tool offset exhibits a homogeneous mechanical mixing and inhibits the formation of brittle intermetallic compounds, which leads to a substantial increment in the mechanical properties of the weld. © 2019, The Indian Institute of Metals - IIM.