Joining of ZrB2 ceramics to Ti6Al4V by Ni-based interlayers

Pure ZrB2 and ZrB2-SiC composites were joined to Ti6Al4V at 1100°C using B-Ni50 (at.%) as a filler alloy. The brazing medium and the processing parameters were chosen on the basis of specific wetting tests which showed the good adhesion properties of the B-Ni alloy with both the ceramic and the Ti alloy; interfacial reactions were foreseen and interpreted by phase diagram analysis. A multilayer metal-ceramic interfacial structure was observed in the joints and a key role was played by Ti coming from Ti6Al4V: it worked as the active element enhancing the adhesion of the liquid to the ceramic and segregated at the interface forming TiB. A satisfactory mechanical performance was obtained for ZrB2-SiC/Ti6Al4V joints, which exhibited a room temperature shear strength of 74 MPa.