Ab initio determination of thermodynamic properties of metals and alloys and their use in phase diagram calculations

0178064 - UFM-A 20033082 RIV BR eng C - Konferenční příspěvek (zahraniční konf.)
Vřešťál, J. - Houserová, Jana - Šob, Mojmír - Friák, Martin
Ab initio determination of thermodynamic properties of metals and alloys and their use in phase diagram calculations.
CONGRESSO ANUAL DA ABM /58./. Rio de Janeiro, 2003, s. 760-770.
[CONGRESSO ANUAL DA ABM /58./. Rio de Janeiro (BR), 21.07.2003-24.07.2003]
Grant CEP: GA ČR GP106/03/P002; GA ČR GA106/02/0877
Výzkumný záměr: CEZ:AV0Z2041904
Klíčová slova: sigma phase * phase diagram ů ab initio methods
Kód oboru RIV: BM - Fyzika pevných látek a magnetismus

Calculation of phase diagram by CALPHAD method requires an expression for the Gibbs energy, with respect to standard element reference states, as a function of temperature, pressure and composition that has to be known for any phase. The problem with dynamic instability appears at non-zero temperatures. In this case, the Gibbs energies have to be regarded as some effective values, when they are used in calculations of phase equilibria at different temperatures. Total energy differences between various structures constitute a part of Gibbs energy differences and can be reliably calculated from first-principles. The Fe-Mo phase diagram presented in this work has been reliably determined using ab initio total energy differences. The values of the enthalpy of formation of sigma-phase found on the basis of the phase equilibria calculations at higher temperature are compared with the energy of formation calculated by means of the LMTO-ASA and FLAPW methods.
Trvalý link: http://hdl.handle.net/11104/0074958