Abstract:TC4 titanium lotus-like core sandwich structure was brazed using TiZrCuNi brazing filler metal. Effect of brazing parameters on brazing interface microstructure and mechanical properties of titanium lotus-like core sandwich structure was investigated. Results show that titanium sandwich structure with excellent brazed quality is attained at the brazing temperature of 920 ℃ with the brazing time of 90 min. The microstructure of the brazing interface consists of acicular α structure and Ti-Cu intermetallic compounds, and the average flat compressive strength of the sandwich structure is 15.14mpa. When the brazing time is short (15min), the diffusion reaction time between Cu and Ni in the liquid solder and the base metal is short, and the diffusion reaction of Cu and Ni into the base metal is not sufficient. The enrichment of Cu and Ni in the brazing interface leads to the content of Cu and Ni exceeding the eutectic composition, which makes eutectic reaction occurred during the solidification process of liquid solder joint after brazing, and thus massive intermetallic compounds are formed. The brazing interface is mainly composed of solidified brazing filler metal containing massive intermetallic compounds and acicular α structure. With the increase of brazing time, the diffusion reaction time of Cu and Ni elements in liquid solder and base metal increases, and the diffusion reaction depth of Cu and Ni elements into base metal increases significantly. As a result, the content of Cu and Ni in the liquid solder decreases significantly, and the element content is less than the eutectic composition point. Cu and Ni are all dissolved in β phase during the solidification process of the liquid brazing seam. When the β phase changes to α phase, the acicular α phase is formed by eutectoid reaction, and intermetallic compound is formed at the interface of acicular α structure. When the brazing time increases from 15min to 90min, the flat compressive strength of TC4 titanium sandwich structure increases gradually due to the decrease of intermetallic compounds in the brazing interface.