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

We present measurements of the pseudobinary phase diagram of the TiSi2-NbSi 2 system. This disilicide system has recently become important because of t he enhanced formation of the low resistivity C54 phase of TiSi2 by addition of Nb. The solubility limit of Nb in C54 TiSi2 at 1000 degrees C is found to lie between 10% and 16% at the metal site, and the solubility limit of T i in C40 NbSi2 at 1000 degrees 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)Si-2 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 res istivity of the C54 phase is increased by 1.2 mu Omega cm per at. % Nb. (C) 1999 American Institute of Physics. [S0021-8979(99)02616-X].