Enhancing interfacial strength of T-joint for vacuum-brazed thin-walled structures comprising TiAl and GH3536 alloys via in-situ synthesis of Al2TiO5 ceramic coatings

Abstract

The joining of dissimilar materials to fabricate lightweight components of thin-walled structures for aerospace applications has garnered significant interest. A pioneering technique has been proposed to achieve an optimal interfacial microstructure and fillet of brazed joints. This technique involves a layer of Al deposited on the surface of TiAl base metal, which aids in the brazing process of the thin-walled structure comprising TiAl and GH3536 alloys. Notably, the addition of the Al layer has a significant impact on the spreading area of molten brazing filler metal, the size of the fillet, and the interfacial microstructure evolution. Consequently, these factors contribute to a substantial increase in the load-bearing capacity of the structure. A comprehensive analysis and discussion are conducted to explore the impact of the Al layer on both the interfacial microstructure and mechanical performance. Under the brazing parameters of 1040 °C/5 min, the peak tensile load reaches a peak value of 362 N, which is 100% higher compared to the joints without Al layer. It is worth noting that fracture occurred in the GH3536 foil after undergoing tensile testing. The dimension of fillet can be controlled through the in-situ synthesis Al2TiO5 ceramic phase on the surface of TiAl alloy. This research offers valuable insights into the production of engineered biomimetic materials and devices, specifically focusing on honeycomb-inspired structures.