Dresden 2011 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 3: Computational Materials Modelling I
MM 3.5: Talk
Monday, March 14, 2011, 12:00–12:15, IFW B
Defects in ferrite: from quantum-mechanical calculations to long-range elastic effects — •Alexander Udyansky1, Johann von Pezold1, Alexey Dick1, Vladimir Bugaev2, and Jörg Neugebauer1 — 1Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf, Germany — 2Max-Planck-Institut für Metallforschung, Stuttgart, Germany
Interstitial Fe-based solid solutions with a low content of C, N, O, B, C+N and H impurities have been studied by combining first principles simulations with the reciprocal space microscopic elasticity theory (MET). This approach allows for a highly efficient description of long-range elastic interactions, which generally control interstitial-interstitial interactions. The short-range chemical interactions, as well as the parameters entering the MET are obtained by density functional theory (DFT) in the generalized gradient approximation, using rather modest supercell sizes. The proposed approach provides a direct insight into the formation mechanism of martensite and its stability limit. For example, tetragonal states are predicted to be preferred even at low impurity concentrations due to a thermodynamically driven orientational ordering of impurities. Furthermore we were able to predict the low impurity concentration part of Fe-based solid solutions phase diagrams and its dependence on the local strain state of the system. Finally, the impurity content is found to strongly affect the vacancy concentration within the host matrix.