Microstructure and mechanical properties of carbon/carbon composites and TC4 joints

C/C composites and TC4 were joined by brazing and using AgCuTi as filler metal at the 860°C-1000°C for 3 min-30 min. The interfacial microstructures and fracture surfaces were investigated by scanning electron microscopy and electron energy spectrum analysis. The results showed that the typical interface microstructure of brazed joints could be expresses as C/C composite/TiC+C/TiCu+ TiC/Ag(s.s)+Ti₃Cu₄ + TiCu/Ti₃Cu₄/TiCu/Ti₂ Cu/Ti₂Cu+Ti(s.s)/TC₄ with the maximal shear strength of 25 MPa at brazing temperature of 910°C for 10 min. The fracture surface analysis showed that the position of fracture surface was related to the orientation of carbon fiber. The joints were fractured in the composites when carbon fiber was parallel to the joined surface. The joints were fractured at the C/C composite/AgCuTi interface when the carbon fiber was vertical to the joined surface.