Features of the spark plasma sintering process of in situ TiC-Ni composites produced by high-energy ball milling

In this study, TiC–Ni composites were fabricated in situ by high-energy ball milling of Ti–C–Ni powder mixtures followed by spark plasma sintering (SPS) at 1000 and 1100 °C. Three compositions were chosen: 30 wt%(Ti C)–Ni, 40 wt%(Ti C)–Ni, and 50 wt%(Ti C)–Ni. During milling, the TiC phase was synthesized and dense nanostructured powder agglomerates of TiC–Ni were formed. The compaction of the products of milling via SPS was accompanied by local melting of the material at the inter-particle contacts caused by high electric current densities. The TiC–Ni composites fabricated by SPS at a temperature of 1100 °C showed relative densities of 98–99 %. Partial melting helps reduce the porosity as pores are filled with the melt. When this melt re-solidifies, nickel-rich regions form in the structure. The phase composition of the materials subjected to SPS is represented by a nickel-based solid solution and non-stoichiometric titanium carbide TiC 0.65–0.8 . The size of TiC reinforcing particles in the sintered composites is less than 1 μm. The Vickers hardness of the composites obtained by SPS at a temperature of 1100 °C from mixtures 30 wt%(Ti C)–Ni, 40 wt%(Ti C)–Ni and 50 wt%(Ti C)–Ni was 740 ± 10 HV 1 , 910 ± 20 HV 1 and 980 ± 30 HV 1 , respectively. • TiC–Ni composites were fabricated in situ by high-energy ball milling. • During following SPS, nearly fully dense TiC-Ni compacts were obtained. • SPS was accompanied by local melting of the material at the inter-particle contacts. • Nickel-rich regions formed in the structure via melt re-solidification during SPS. • The iron and chromium contamination was introduced to the material at milling stage.