The microstructure and mechanical properties of C/C composite/Ti3Al alloy brazed joint with graphene nanoplatelet strengthened Ag-Cu-Ti filler

Carbon/carbon (C/C) composite and Ti3Al alloy were brazed using graphene nanoplatelet (GNP) strengthened Ag-Cu-Ti composite filler. The brazed joint had the excellent bonding interface, and the microstructure of joint contained TiC, Ti(Cu,Al), GNPs, AlCu2Ti phases. Results showed that the GNPs addition could decrease the thickness of TiC layer. GNPs hindered the atom diffusion and inhibited the growth of TiCu phase on the Ti3Al alloy side. The shear strength of brazed joint first increased and then decreased with the increase of GNPs content, and the brazed joint reached to the highest shear strength 26.7 MPa when GNPs content was 0.1 wt. %. GNPs could reduce the CTE mismatch between C/C composite and Ti3Al alloy, and improve the joint strength due to the relief of residual stress.