Experimental evidence and possible mechanism of melt formation at the inter-particle contacts during spark plasma sintering of TiC-Cu composite particles

In the present work, the evidence of the melt formation at the contacts between composite TiC-Cu particles formed by high-energy ball milling was found in the microstructure of compacts obtained by spark plasma sintering at real temperatures of the sample of 725–925 °C. The voltage drop associated with a contact that could have been heated up to the melting point of copper was calculated to be much higher than the voltage across the whole sample during SPS. As the formation of melt could not be attributed to simple overheating of small cross-sectional area contacts (bridges), another explanation of the observed effect was sought. A mechanism based on the micro-arc formation was proposed to explain the observed melt formation in the sintered composites.