Ab initio study of Ti–C precipitates in hcp titanium: Formation energies, elastic moduli and theoretical diffraction patterns

The Ti–C system is poorly studied at low carbon concentrations (<1 at.%). This region is important because Ti–C dispersed phases can improve thermal stability of commercially pure nanostructured α-Ti alloys. We developed based on first principles new method which allows to predict formation of precipitates at low concentrations of impurities in metallic matrix. Using this method probabilities of formation of Ti–C phases in α-Ti were computed. It was found that most favourable phases at 200–800 K are Ti2C and Ti3C2. Elastic moduli and diffraction patterns of most favourable Ti–C phases are also presented.