Phase equilibria in Nb-W-rich zone of the Nb-W-Si ternary system

Abstract

In this paper the solidification behavior and phase stability in Nb-W-Si alloys near the Nb-W binary are described. A partial liquidus surface projection of the Nb-W-Si system is constructed based on the observations of microstructure evolution during solidification. Microstructural and microchemical evidences prove the existence of the following eutectic and peritectic reactions: L → β(Nb, W)5Si3 + Nbss; L + β(Nb, W)5Si3 → (Nb(W))3Si; L → (Nb(W))3Si + Nbss. One invariant point for reaction of L + β(Nb, W)5Si3 → (Nb(W))3Si + Nbss is determined near composition Nb-16Si-3W. Moreover, phase stabilities at 1773 K in these alloys are briefly described by identifying the constituent phases after prolonged annealing treatment.