Phase equilibria in the Co–Ta–W system at 1373 and 1473 K

Abstract

The phase equilibria of the Co–Ta–W system at 1373 K and 1473 K were determined using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD), two isothermal sections were constructed. Four three-phase regions at 1373 K were identified and three three-phase regions at 1473 K were determined. At heat-treatment temperature of 1373 K, the solid solubility of W in λ₂ and Co₇Ta₆ were measured to be about 23.3 at.% and 11.9 at.%, respectively, while the solubility of Ta in Co₇W₆ was about 13.7 at.%. And Ta-stabilized Co₃W phase was stable at 1373 K. At heat-treatment temperature of 1473 K, the solid solubility of W in λ₂, Co₇Ta₆, and CoTa₂ were measured to be about 23.8 at.%, 15.7 at.%, and 3.9 at.%, respectively. No new phase was found in this work.