Fabrication of TiB-TiC, TiB-TiN and TiB2-TiC composites and their bonding to Ti-6Al-4V alloy by spark and resistance sintering

Mixture of TiB2, Ti and TiC or TiN Powder as well as TiB2 and TiC powder were spark- and resistance-sintered to obtain TiB-TiN, TiB-TiC and TiB2-TiC composites. In addition, the plates of these composites were bonded to Ti-6Al-4V alloy substrate by the resistant-sintering. The Vickers hardness and the bending strength of TiB-TiC and TiB-TiN composites reach their maxima at about 20 mol% of TiN or TiC, while those of Tib(2)-TiC composite take the maxima at about 70 mol% of TiC. The bending strength of the TiB2-70 mol%TiC composite is larger than that of the TiB-20 mol%TiC composite when the sintering temperature is 1973 K. However the bending and adhesion strengths of TiB-20 mol%TiC composite layer bonded on Ti-6Al-4V alloy are larger than those of the TiB2-70 mol%TiC layer when the bonding temperature is 1673 K. The bending strength of the TiB-20 mol%TiC bond layer increases with decreasing ratio of bond layer thickness to substrate thickness, which can be explained by the existence of residual stress introduced during cooling after bonding at high temperature.