Brazing of diamond to invar with Ag-Cu-Ti filler alloy: Wettability, microstructure and mechanical performance

Diamond and Invar were brazed with Ag-Cu-Ti filler alloy. Contact angle of the Ag-Cu-Ti/diamond system was measured, and its wetting behavior was explored. The interfacial structure of the joint was analyzed through brazing temperature and dwell time. The typical interfacial structure of diamond/Ag-Cu-Ti/Invar alloy brazed joints was diamond/TiC/Ag(s, s) + Cu(s, s)/Fe2Ti + Ni3Ti/Fe2Ti/Invar alloy. With increasing brazing temperature or dwell time, the thickness of the TiC layer and the quantity of Fe2Ti and Ni3Ti phases increase. The shear strength tests show that the maximum shear strength of 257.4 MPa was obtained with the parameters at 870 °C for 10 min. In addition, the impact of processing parameters on fracture location and fractographs of brazed joints was discussed.