Abstract
Titanium Ti6Al4V and aluminum 5A05Al were cold arc MIG welded using Al-Si5 filler. The feasibility of Ti/Al dissimilar cold arc MIG welding-brazing was investigated by microstructure examination and fractography. Welds without defects were fabricated; however, the Ti/Al interface exhibited non-uniform structures. A multilayered structure, including an α -Ti layer, a TiAl₃ + Ti₅Si₃ mixed layer, and a serrate TiAl₃ layer, was observed in the upper regions. In comparison, only a thin cellular TiAl₃ layer was observed in other regions. Two types of fracture modes, including a ductile fracture mode and a mixed brittle-ductile fracture mode, were observed in a single joint. The ultimate tensile strength of the Ti/Al joints surpassed 240 MPa.

Key words
dissimilar joining, cold arc welding, welding-brazing, microstructure, fractography

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