Characterisation of solar-synthesised TiCx (x=0.50, 0.625, 0.75, 0.85, 0.90 and 1.0) by X-ray diffraction, density and Vickers microhardness

Homogeneous single-phase hypo-stoichiometric carbide TiCx of titanium with known stoichiometric ratio x (0.50, 0.625, 0.75, 0.85, 0.90 and 1.0) was prepared from mixed powders of Ti metal and graphite through 30 min solar heating in inert Ar atmosphere and characterised by X-ray diffraction (XRD), density ρ and Vickers microhardness Hv. In spite of short radiation period at relatively low temperature (no higher than 1600 °C), formed TiCx specimens were all with relatively high degree of crystallinity judging from good separation between Kα1 and Kα2 peaks of XRD patterns at high (h k l) index. Measured density of prepared TiCx powders was practically identical to the calculated value from the measured lattice parameter for respective x implying that f.c.c. (face centred cubic) Ti lattice was with no defect and 100x% of the O-sites (octahedral interstitial sites) were filled with C atoms leaving the rest 100(1−x)% of O-sites vacant. Reflecting polycrystalline nature of the prepared TiCx compact, measured Hv scattered over range of ±400 around 1100. Application of 50 h heat treatment at 600 °C appeared to realise C atoms ordering re-configuration over O-sites leading to slight extent of tetragonal distortion for TiCx specimens with x=0.50 and 0.625.