Thermodynamic analysis of the topologically close packed ? phase in the Co-Cr system
Peisheng Wang, Matthew C. Peters, Ursula R. Kattner, Kamal Choudhary, Gregory B. Olson
Density functional theory (DFT) calculations show that a thermodynamic description considering the magnetic contribution to the total energy for the end-members of the σ phase is necessary. A more straightforward method to use the DFT results in a CALPHAD (Calculation of phase diagrams) description has been applied in the present work. It was found that only the results from DFT calculations considering spin polarization are necessary to obtain a reliable description of the σ phase. The benefits of this method are: The DFT calculation work can be reduced and the description of the magnetic contribution is more reliable. A revised thermodynamic description of the Co-Cr system is presented which gives improved agreement with experimental phase boundary data for the σ phase.