DISORDER-ORDER PHASE-TRANSFORMATIONS AND ELECTRICAL-RESISTIVITY OF NONSTOICHIOMETRIC TITANIUM CARBIDE

Phase transformations of the disorder-order type in the homogeneity re gion of nonstoichiometric titanium carbide TiCy (0.5<y<1.0) have been studied. It has been established that, depending on the actual composi tion of TiCy, these may form in it for T<980-1000 K a cubic or a trigo nal ordered Ti2C phase (space groups Fd3m and R (3) over bar m, respec tively) and a rhombic ordered Ti3C2 phase (space group C222(1)). The e ffect of ordering on the electrical resistivity of the nonstoichiometr ic carbide TiCy was studied, and the temperatures of the reversible di sorder-order equilibrium transitions determined. The ordering in titan ium carbide is shown to be a first-order phase transition. (C) 1998 Am erican Institute of Physics.