Poorly sinterable TiN powders have been fully densified using a spark plasma sintering (SPS) technique. Sintering characteristics and microstructural evolution during SPS processing were evaluated using electron microscopy. It was found that Al2O3 incorporated as a contaminant during the milling process reacted with TiN particles at temperatures above 1700oC to form a secondary phase containing Al2O3 that accelerated the mass transport. This secondary phase makes it possible to start sintering at a lower temperature. It also enables the growth of TiN grains to be controlled. This phenomenon could be confirmed by the presence of the round or curved grain boundaries and the presence of Al2O3 containing secondary phase clusters in grain boundary triple junctions.

Keywords: Spark plasma sintering, TiN, Microstructures, Grain size distribution