Experimental Determination of Phase Equilibria in the Co-Cr-Ni System

The phase equilibria between the γ (A1) and liquid phases and those between the γ, ε (A3), σ (D8b) and α (A2) phases at temperatures between 750 and 1300 °C in the Co-Cr-Ni system were determined by differential scanning calorimetry and electron probe microanalysis. It was found that the γ solidus and liquidus temperatures decrease with increasing Cr or Ni content and that the difference between them increases with increasing Cr content. The phase equilibria at 800, 900, 1000, 1100, 1200 and 1300 °C were determined using two- or three-phase alloys, and the phase boundaries due to the magnetically induced phase separation in the γ and ε phases were also observed at 850, 800 and 750 °C by the diffusion couple method.