Core-rim structure formation in TiC-Ni based cermets fabricated by a combined thermal explosion/hot-pressing process

TiC-Ni-based cermets were obtained by thermal explosion from different elemental mixtures (Ti, C, Ni and X, where X=Cr, Mo or W) and subsequently densified by hot-pressing under a cyclic load. The whole process was performed in a single stage in the same experimental device according to the following thermal and pressure procedure: a heating rate ramp up to 1573K without applying any load followed by an isothermal dwelling under a compressive cyclic load of 32MPa. The thermal explosion synthesis occurred during the heating ramp at a temperature close to 1273K that was practically independent of the starting nominal composition. The influence of different refractory elements on the chemical composition and microstructure of cermets was studied. SEM characterization showed that only with Mo and W, the cermets developed the characteristic core-rim structure. A high densification was achieved, but decreased when the refractory elements were added. Nevertheless, in these cases higher hardness values were obtained. •The structure of TiC-Ni based cermets containing Mo or W obtained by thermal explosion (TE) and hot-pressing (HP) shows specific core-rim structure constituted by mixed carbides (Ti, Mo)C or (Ti, W)C with different contents of heavy metal.•The cermets structure formation is governed by two dissolution-reprecipitation mechanisms first, in the transient liquid phase during exothermic peak and second, in solid phase during isothermal dwell•After TE process, the formation of the conventional core-rim structure remains heterogeneous and incomplete.•The final densification and well developed core-rim structure is obtained after (TE + HP) regime and the structure is formed of particles with multiple rim layers.•The nature of the additions and the applied regime significantly influence the material stress strain.