Enhancing the sintering ability of TiNx by introduction of nitrogen vacancy defects

Highly nitrogen-deficient non-stoichiometric TiNx, powders within nitrogen vacancy defects (0.3 < x < 0.5) were prepared by mechanical alloying and consolidated by high pressure sintering. The effects of nitrogen vacancy defects, sintering temperature and pressure on densification and grain growth of TiNx were investigated for improving sintering ability and mechanical properties. Increasing nitrogen vacancy defects promoted densification and grain growth of TiNx. Nitrogen vacancies accelerated material transport and diffusion during sintering and altered strong covalent bonding nature was believed to result in enhanced sintering ability. Densification of TiNx was enhanced by increasing temperature and elevating pressure, grain growth was promoted by increasing temperature, whereas restrained by elevating pressure. TiNx (x=0.32) ceramic with relative density of 99.4% and average grain size of 21 nm. was obtained at 1200 degrees C, 5 GPa and 10 mm. Vickers hardness of 22.6 GPa and fracture toughness of 5.0 MPa m(1/2) were achieved. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.