Spark plasma sintering of Ti(C, N) cermets with intermetallic binder phases

Dense cermets have been obtained from Ti(C0.5, N0.5)–Mo2C–Ni and Ti(C0.5, N0.5)–Mo2C–Ni–TiAl3 powder mixtures by spark plasma sintering (SPS). The Ti(C0.5, N0.5)–Mo2C–Ni alloy presents significant exudation of the liquid phase through the clearance between SPS punches and die. However, this phenomenon is almost negligible for the composition with TiAl3 additions. These cermets show wide Ti(C, N) grain size distributions with a significant fraction of Ti(C, N) grains in the nanometric range. The binder phase of the cermet with TiAl3 additions has a crystalline structure similar to that of the γ′ phase and a dispersion of (Al, Ti) rich oxides which are the result of “in situ” reduction of powder oxides by Al. The presence of ultrafine Ti(C, N) grains along with the relatively tough behaviour of the binder phase lead to a combination of hardness and toughness (HV10 over 18 GPa and KICS around 7.5 MPa √m) close to the range covered by ultrafine WC–Co hardmetals of similar binder content.