Synthesis of TiC–TiB2–Ni cermets by thermal explosion under pressure

TiC/TiB2-based cermets were fabricated in situ by means of the thermal explosion under pressure technique starting from Ti–B4C powders with the addition of varying contents of Ni metal binder to achieve near-net-shape bulks. The combustion reaction was ignited in a graphite die heated by current. Full conversion of the reactants was obtained by thermal explosion and the process yielded TiC–TiB2–Ni materials characterised by a fine microstructure. Appreciable differences in terms of microstructure, hardness and fracture toughness by indentation were observed between core and external surface of the products due to fast cooling caused by heat transfer to the die walls. Cermets with a high content of Ni showing high hardness and fracture toughness were obtained, with values of HV5 = 2182 and KIc = 8.8 MPa m1/2 for 30 wt.% Ni and of HV5 = 1684 and KIc = 12.7 MPa m1/2 for 47 wt.% Ni.