Phase formation and resistivity in the ternary system Ti–Nb–Si

We present measurements of the pseudobinary phase diagram of the TiSi2–NbSi2 system. This disilicide system has recently become important because of the enhanced formation of the low resistivity C54 phase of TiSi2 by addition of Nb. The solubility limit of Nb in C54 TiSi2 at 1000 °C is found to lie between 10% and 16% at the metal site, and the solubility limit of Ti in C40 NbSi2 at 1000 °C is between 76% and 79.5% at the metal site. Adding Nb to C54 TiSi2 increases the unit cell volume at a rate of 0.035% per at. % Nb. Adding Nb to C40 (Ti,Nb)Si2 increases the unit cell volume at a rate of 0.034% per at. % Nb. The presence of Nb enhances the formation of the C54 phase and improves its thermal stability. The desirable low resistivity of the C54 phase is increased by 1.2 μΩ cm per at. % Nb.