Experimental investigation of phase equilibria in the Nb–Si–Ta ternary system

Abstract

The phase equilibria in the Nb–Si–Ta ternary system at 1 373 K, 1 473 K and 1 573 K were investigated by means of back-scattered electron imaging, electron probe microanalysis and X-ray diffraction. The isothermal sections at 1 373 K, 1 473 K and 1 573 K consist of two three-phase regions and seven two-phase regions, without any ternary compounds. The compounds of NbSi ₂ and TaSi ₂, αNb ₅Si ₃ and αTa ₅Si ₃ form continuous solid solutions, respectively. The solubilities of Nb in Ta ₃Si and Ta ₂Si phases are extremely large, whereas the solubility of Si in the β(Nb, Ta) phase is relatively small.