Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1625776 | Journal of Alloys and Compounds | 2007 | 7 Pages |
In situ neutron diffraction has been employed to investigate the formation of TiCx from the elements at relatively low temperatures, beginning at T ∼∼ 1073 K. Slow heating of the mixture of the elements precludes the generation of sufficient heat to induce a self-propagating high temperature synthesis (SHS), reported in the literature for this system. We observe that the reaction starts well before the α –β transition in Ti occurs, which implies that in this case this transition does not serve as a trigger mechanism for SHS. An extensive coexistence of both polymorphs of titanium suggests that a significant amount of carbon diffuses into the hexagonal α-Ti lattice and stabilizes it with respect to the cubic β-phase. This is supported by the observation of an anomalous increase of the c -lattice parameter of the α-Ti lattice above the transition temperature for pure α-Ti. Density functional theory (DFT) based calculations support this interpretation. The energetics of the carburization of α-Ti have been obtained from the DFT calculations.