Abstract

Abstract The phase equilibria of the Mo–Si–V ternary system were experimentally determined, including the isothermal sections at 1200 and 1450 °C, as well as the liquidus surface projection. The microstructures, crystal structures and phase constitutions of the as-cast and the annealed alloys in whole composition range were investigated by means of scanning electron microscopy equipped with energy dispersive spectroscopy, electron probe microanalyzer and X-ray diffraction. Five three-phase regions and ten two-phase regions were confirmed and no ternary compounds were observed in isothermal sections at 1200 and 1450 °C. In addition, the solidification paths of different Mo–Si–V alloys were analyzed to verify the primarily solidified phases. The stoichiometric compounds Mo5Si3 and V5Si3 have the same structure-type (W5Si3), however, they have two different compositions in the Mo–Si–V ternary system. They form two-line compounds Mo-rich Mo(V)5Si3 and V-rich V(Mo)5Si3. Eight primary solidification regions were finally confirmed on the basis of the study on the solidification processes of the as-cast alloys. The present experimental results are useful for the thermodynamic assessment of the Mo–Si–V ternary system, and the database development for the multi-component Nb/Mo–Si-based superalloy system.

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