ICAMS / Interdisciplinary Centre for Advanced Materials Simulation
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Sampling free energies of different phases in Fe including atomic and magnetic degrees of freedom

Date: 07.03.2016
Place: DPG Spring Meeting, Regensburg, Germany

Martin Staadt
Jutta Rogal
Tilmann Hickel
Thomas Hammerschmidt
Jörg Neugebauer
Ralf Drautz

The phase transition between ferrite and austenite in iron is omnipresent during manufacturing and processing of steels. Due to the combination of a structural and a magnetic transition from paramagnetic FCC to ferromagnetic BCC iron, these phase transitions are particularly challenging to investigate on the atomistic level. Previous studies were limited to embedded atom potentials that did not explicitly account for magnetism or density functional theory that proved to be too computationally expensive for a direct simulation. We overcome these limitations by using bond- order potentials that enable us to treat larger system sizes but still properly treat magnetism. Using the BOPfox code, we calculate free energies of the bulk phases and the phase boundaries with thermodynamic integration including all important contributions.

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