Reaction-composite brazing of carbon fiber reinforced SiC composite and TC4 alloy using Ag-Cu-Ti-(Ti+C) mixed powder

Carbon fiber reinforced SiC (Cf/SiC) was successfully joined to TC4 alloy with Ag-Cu-Ti-(Ti+C) mixed powder by proper parameters. The interfacial microstructure was investigated by scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and X-ray diffraction (XRD). The mechanical properties of the brazed joints were measured by a mechanical testing machine. The results show that the Ti element in the interlayer can react with the brazed composite, the brazed joints mainly consist of TiC, Ti3SiC2, Ti5Si3, Ag, residual graphite, TiCu, Ti3Cu4 and Ti2Cu reaction products, and the performed joints have dense bonding layers reinforced by residual graphite and in situ synthesized TiC from reaction between C and Ti in the filler materials. The TiC particulates obviously relax the thermal stress in the heterogeneous joint resulting in an increase in shear strengths of the brazed joint. The maximum shear strengths of the brazed joints at room temperature, 500 °C and 800 °C are 145 MPa, 70 MPa and 39 MPa, respectively. The shear strengths of the joints are remarkably higher than the optimal of the joints brazed with Ag-Cu-Ti.