TIG welding-brazing of Ti6Al4V and Al5052 in overlap configuration with assistance of zinc foil

Under tungsten inert gas heating, a sound Ti6Al4V/Al5052 lap joint was obtained with the addition of zinc, which enhanced the spreadability of Al-based filler on Ti6Al4V substrate. Under high heat input, a serrated TiAl3 layer, which was replaced by a TiZn16 + TiAl3 dual sublayer under low heat input, was observed at the brazing interface. TiAl3, Si, and Al-Si eutectic compounds were found in the fusion zone. The microhardness of the fusion zone was higher than those of the heat-affected zone and the Al5052 substrate given the presence of intermetallic compounds. At the optimal welding current of 80 A, the tensile-shear strength of the joint reached 180 MPa, which was equivalent to 80% the tensile-shear strength of the base Al5052 alloy. Failure occurred at the welded seam. The fracture surface was characterized by quasi-cleavage patterns. The effect of zinc on the spreadability of liquid filler metal and the formation of the Ti6Al4V/Al5052 lap joint were discussed.

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