Influence of Zr addition on TIG welding–brazing of Ti–6Al–4V toAl5A06

TIG welding–brazing of Ti–6Al–4V to Al5A06 alloys with pure Al and Al–Cu–Zr fillers was investigated. The Zr and Cu additions enhanced the spreadability of Al-based fillers on Ti–6Al–4V substrate under TIG heating condition, and a sound Ti/Al dissimilar butt joint was obtained. Influenced by Zr addition, a discontinuous TiAl3 layer with a thickness of 2–4 μm was observed at the Ti/seam interface under a low heat input condition, which was replaced by TiAl3+L–(Ti,Zr)Al3+H–(Ti,Zr)Al3 multi-sublayers when a high heat input was adopted. The joint with Al–Cu–Zr filler has higher tensile property and wider processing parameters than that with pure Al filler. The largest tensile strength of the joint produced by Al–Cu–Zr filler reaches 284 MPa up to 85% of base Al5A06 alloys, and the fracture occurred by quasi-cleavage mode at the TiAl3 sublayer. Zr addition was favorable to enhance the spreadability on Ti substrate, and the welding processing parameters were broadened by the presence of Zr addition.