Experimental determination of the phase equilibria in the Co–Fe–Zr ternary system

The phase equilibria in the Co–Fe–Zr ternary system were investigated by means of optical microscopy (OM), electron probe microanalysis (EPMA), X-ray diffraction (XRD), and differential scanning calorimetry (DSC) on equilibrated ternary alloys. Four isothermal sections of the Co–Fe–Zr ternary system at 1300 °C, 1200 °C, 1100 °C and 1000 °C were experimentally established. The experimental results indicate that (1) no ternary compound was found in this system; (2) the solubility of Fe in the liquid phase of the Co-rich corner at 1300 °C is extremely large; (3) the liquid phase in the Zr-rich corner and the (Co,Fe)2Zr phase form the continuous solid solutions from the Co–Zr side to the Fe–Zr side; (4) the solubility of Zr in the fcc (Co, Fe) phase is extremely small.

Research highlights
► We determined four isothermal sections of the Co–Fe–Zr system from 1000 °C to 1300 °C.
► No ternary compound was found in the Co–Fe–Zr ternary system.
► The solubility of Fe in the liquid phase at 1300 °C is extremely large.
► The (Co, Fe)2Zr phase form the continuous solution from Co–Zr side to Fe–Zr side.
► The solubility of Zr in the fcc (Co, Fe) phase is extremely small.