Experimental determination and thermodynamic assessment of the Co-Ni-Ti system

The isothermal section at 1273 K of the Co-Ni-Ti system was determined using equilibrated alloys by means of scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The experimental results indicated that eight three-phase regions and a ternary compound τ with Co3V-structure existed. Meanwhile, this system was thermodynamically modeled using the CALculation of PHAse Diagram (CALPHAD) method. The isothermal section at 1273 K measured in this work as well as the four isothermal sections at 1373, 1273, 1223 and 1173 K and the liquidus surface projection from the literatures were taken into account in the present optimization work. A set of self-consistent thermodynamic parameters of the Co-Ni-Ti system was first derived.