Sintering behavior of titanium–titanium nitride nanocomposite powders

The sintering behavior of titanium–titanium nitride nanocomposite powders has been investigated by dilatometry. Micron-sized titanium powders of average particle size of ∼12 μm and nano sized titanium nitride powders of average particle size of ∼50 nm were used to produce two compositions of Ti–8 wt%TiN and Ti–15 wt%TiN by physical mixing and ultrasonification. Dilatometry was carried out by constant rate of heating (10 °C/min) to various temperatures in the range of 650–1250 °C followed by isothermal holding for 1 h. The effect of nano TiN dispersion on the sintering onset temperature, linear shrinkage, shrinkage rate, activation energy, and microstructure of titanium was investigated. The sintering of titanium–titanium nitride nanocomposites was found to be influenced by the sintering between the Ti–Ti contacts (self diffusion), Ti–TiN contacts (diffusion of N into Ti), TiN–TiN contacts, the role of oxygen as well as the α–β transformation in titanium.