Brazing of TA32 Ti-based alloy with honeycomb structure and the joint microstructure

TA32 is a near-alpha titanium alloy and is a specific grade of titanium alloy that is known for its high strength, lightweight, and excellent corrosion resistance. Using the optimized filler metal composition and a 900℃/40-minute holding process, a relatively uniform interface microstructure with high strength was achieved for TA32 honeycombs with a 8.4mm cell size and 0.1 mm wall thickness. The joint strength of the honeycomb was increased from room temperature to 500 ℃ and it was decreased at 550℃. Under the 900℃/40-minute holding process, the 0.1 mm thick TA32 thin strip did not undergo grain growth or phase transformation. Titanium is the dominant element in the interface, while Cu and Ni from the filler metal are concentrated at the center. The central interface primarily consists of a titanium-based solid solution (HCP structure) with trace TiNi₃ phase; no TiCu₂ or Ti₂Cu phases were detected. The operating temperature of this TA32 honeycomb structure should not exceed 550°C.