Experimental study and thermodynamic re-assessment of the binary Al-Ta system

Phase relations in the binary Al-Ta system were re-assessed taking into account recent experimental data. Alloys of different composition were prepared and analyzed by means of DTA, DSC, pyrometry after Pirani-Alterthum, SEM/EDS and SEM/EBSD techniques in order to prove the phase relations in the system. Both, as-cast and annealed samples were investigated. A new thermodynamic description of the binary Al-Ta system was obtained by CALPHAD modeling of the Gibbs energy of all accepted individual phases, taking into account the above experimental data as well as assessed published data. Applying the results, calculations of the phase diagram and thermodynamic properties were performed with the Thermo-Calc software. They are shown to reproduce properly experimental data.