Suppressing the brittleness of Ti/Cu weld joint in TIG welding by alloying Fe in filler metal

The inherent brittleness of Ti/Cu weld joints, which is primarily caused by the formation of Ti-rich intermetallic compounds (IMCs) such as Ti 2 Cu and TiCu at the interface, severely limits their structural reliability. In this study, we propose a novel strategy to suppress IMC formation by alloying Fe into the Cu filler metal as a self-dispersing “capture agent” during TIG welding. Upon melting, Fe induces liquid-phase separation, forming Fe-rich droplets that preferentially react with Ti to form TiFe 2 —a phase with a more negative enthalpy of formation than Cu-Ti IMCs. This reaction effectively consumes Ti atoms in the molten pool, significantly reducing the thickness of the brittle Ti-rich IMCs layer and promoting the formation of dispersed Fe-Ti-Cu particles. With increasing Fe content from 0 to 30 wt.%, both the tensile strength and elongation of the joint are enhanced. The joint fabricated with Cu70Fe30 filler metal achieves a tensile strength of 190.5 MPa, equivalent to 83% of the Cu base metal (BM) strength, along with an elongation of 22.5%. This study provides a novel approach for the welding of Ti/Cu dissimilar metals.