Microstructure and performance analysis of vacuum brazing welded titanium joints in honeycomb sandwich panel structure

The processing parameter of titanium alloy honeycomb sandwich structure was studied, using filling foil of Ti-Zr-Ni-Cu based metal.The vacuum degree was not lower than 2×10^-3 Pa and the brazing temperature was 930 ℃with a holding time of 30 min. The ultrasonic testing(NDT) results showed an excellent brazing weld with no welding-off and faulty welding. The microstructure of the brazed joint was examined by means of scanning electron microscopy(SEM) and energy dispersive spectroscopy (EDS). The results showed that mutual diffusion was happened between the filler metal and the base metals resulting in the precipitation of new phases. Using the optimized parameters, the average tensile strength of joint was 12.8 MPa, the shear strength was 9.01 MPa. The fracture mode of the vacuum brazing joints belonged to a brittle type fracture