Vacuum brazing of Cf/β-spodumene composites and Ti-6Al-4 V alloy using Ag-Cu filler metal

Interfacial microstructure and mechanical properties of Ti-6Al-4 V/C-f/beta-spodumene composites joints brazed by Ag-Cu eutectic brazing filler were investigated. The effects of brazing temperature and holding time on the interfacial microstructure and mechanical properties of Ti-6Al-4 V/C-f/beta-spodumene compoktes joints were studied. The result indicated that the typical interfacial microstructure of the joint was Ti-6Al-4 V/Ti2Cu + alpha-Ti (s,s)/Ti2Cu/TiCu/Ag (s,s)/Cu (s,s)/Ti2Cu3/TiSi2 + TiC/C-f/beta-spodumene composites. The thickness of the diffusion layer, Ti2Cu3 layer, and reaction layer on the interface of C-f/beta-spodumene composites increased with the brazing temperature or holding time increasing, meanwhile, the thickness of Ti-Cu layers decreased. The diffusion of Ti in brazing seam, which was significantly determined by the brazing temperature and holding time, was a decisive factor on the interfacial microstructure and mechanical properties of brazed joints. The optimal shear strength of joint brazed at 880 degrees C for 10 min was 33.5 MPa. Further raising the brazing temperature or extending the holding time would reduce the shear strength of joints. Brazing specimens brazed at 880 degrees C and 910 degrees C for 10 min broke in form of cleavage fracture after shearing test. Moreover, the formation of excessive thickness of TiSi2 + TiC layer or Ti3Cu4 reaction layer was harmful to the mechanical property of the joint.