Calculation of phase diagram of hafnium- tantalum system by using the theoretical method

Abstract EN

In this research the phase diagram of (Hf-Ta) binary system has been evaluated through (CALPHAD) [calculation of phase diagrams] method by using the experimental data of phases equilibria and thermodynamic properties.

The computer programs in the language of quick basic have been formulated for the calculation of stable phases relations with mole fraction as a function of temperature, the basis of these programs is the approximate representation of free energy-mole fraction curves.

The Gibbs free energy of the liquid, body centered cubic and hexagonal closed packed were calculated by the regular solution model.

The present results were shown a good agreement between the theoretical and experimental diagrams.

The eutectoid point in the theoretical diagram was XTa = 0.24 and Tth = 1609.4 while the eutectoid point in the experimental diagram was XTa = 0.2and Tex = 1366.