Effect of copper interlayer in dissimilar TA6V/AU4G rotary friction weld joints

Welding titanium to aluminum alloys is difficult and challenging due to the differences in their chemical and physical properties. The aim of this research is to investigate the effect of integrating a pure copper (Cu) interlayer on the mechanical behavior and the microstructure of the dissimilar TA6V/AU4G Rotary Friction Weld (RFW) joints. Tensile tests and microhardness measurements were conducted to demonstrate the mechanical behavior of the RFW joints. Microscopic observations were carried out to identify the structural nuances and quality of the weld joint. Energy Dispersive X-Ray (EDX) analysis was performed to reveal the interdiffusion phenomenon at the weld interfaces, and the present phases were identified through X-Ray Diffraction (XRD) analysis. The results suggest that adding a Cu-interlayer changes the flow direction of thermoplastically deformed material, leading to an increase in the Ultimate Tensile Strength (UTS) value up to 393.34 MPa. The microhardness profile of the TA6V/Cu/AU4G RFW joint is similar to that of the TA6V/AU4G joint, except for noticeable difference at the interface. In addition, the use of a Cu-interlayer has been shown to be more effective in preventing the formation of brittle TiAl₃ intermetallic compounds (IMCs) compared to direct TA6V/AU4G welds. The inclusion of a Cu-interlayer results in a significant improvement in joint efficiency by 105.32%, demonstrating the effectiveness of the Cu-interlayer in enhancing the mechanical properties of the dissimilar TA6V/AU4G RFW joints.