Experimental study and reassessment of the Ni-Ta binary system

The phase boundaries of the solid phases of the Ni-Ta system at 1473 K, 137 3 K and 1173 K were determined using the diffusion couple and EPMA techniqu es. The Ni-Ta binary system was then assessed by means of the CALPHAD metho d. Considering the crystallographic and the phase stability information, a new model, (Ni,Ta),(Ta), (Ni,Ta)(2)(Ni)(6), was used to describe the NiTa p hase. A set of parameters describing the Gibbs energy of each phase was obt ained. Calculated quantities were compared with experimental data, and they are in good agreement. Using a thermodynamic approach, the crystallization temperatures T-x and the glass forming range of Ni-Ta system were calculat ed. In most cases, the calculation represented the experimental data well.