Phase Diagram of the Nb—Nb₅ Si₃ System and Crystal Structure of the Compound Nb₃Si

Abstract

The phase diagram of the Nb—Nb₅Si₃ system is presented. In alloys of this system there is a compound Nb₃Si formed by a peritectic reaction at 1880^°C; it is stable down to 1800^°. Prolonged annealing at lower temperatures leads to the decomposition of this compound. The critical structure of Nb₃Si is determined (Ti₃P type, space group P4₃/n-C4_r, tetragonal cell, a = 10.230 A, c = 5.189 Â, c/a = 0.507).