Preparation of nanostructured Cr1−xTixN ceramics by spark plasma sintering and their properties

Nanostructured Cr1−xTixN ceramics were prepared by a spark plasma sintering technique, using Cr1−xTixN powders (30–40 nm) synthesized through a high-temperature nitridation method. The sintering, microstructure and properties of the materials were investigated. It was found that the nitride powders were highly sintering active, and fully densified ceramics with a grain size of less than 100 nm could be obtained at a low sintering temperature of ∼1100 °C. In addition, the high-temperature decomposition of CrN was effectively suppressed under spark plasma sintering conditions, and the thermal stability of CrN was improved by forming a Cr1−xTixN solid solution. The lattice constant of Cr1−xTixN showed a continuous increase with increasing TiN concentration, and so did the hardness and grain growth rate; the electrical resistivity continuously decreased. The fundamental reasons accounting for these phenomena are discussed.