TY - THES

T1 - Planar faults in γ-TiAl

T2 - An atomistic study

AU - Dumitraschkewitz, Phillip

N1 - embargoed until 11-05-2016

PY - 2015

Y1 - 2015

N2 - In this Master Thesis two different methodologies for building atomic models of planar faults in gamma-TiAl are implemented. The generalized stacking fault energy for stoichiometric TiAl is calculated within the framework of Density Functional Theory and Molecular Dynamics with the code packages VASP and LAMMPS, respectively. Different energy profiles corresponding to different dislocation dissociation schemes are discussed. The impact on the stacking fault energies for different relaxation methods, varying cell volume and using different exchange correlation potentials is examined. A simple model is implemented to get trends for different alloying elements. The most striking results are that the stacking fault energies depend on the chosen relaxation method due to the fact that their energy minimum do not lie exactly on their hard-sphere model positions and that the ratio (Ti+X)/Al has a huge impact, generally finding lower stacking fault energy values for ratios bigger than 1.

AB - In this Master Thesis two different methodologies for building atomic models of planar faults in gamma-TiAl are implemented. The generalized stacking fault energy for stoichiometric TiAl is calculated within the framework of Density Functional Theory and Molecular Dynamics with the code packages VASP and LAMMPS, respectively. Different energy profiles corresponding to different dislocation dissociation schemes are discussed. The impact on the stacking fault energies for different relaxation methods, varying cell volume and using different exchange correlation potentials is examined. A simple model is implemented to get trends for different alloying elements. The most striking results are that the stacking fault energies depend on the chosen relaxation method due to the fact that their energy minimum do not lie exactly on their hard-sphere model positions and that the ratio (Ti+X)/Al has a huge impact, generally finding lower stacking fault energy values for ratios bigger than 1.

KW - TiAl

KW - Stapelfehlerenergie

KW - generalisierte Stapelfehlerenergie

KW - Ab initio

KW - Molekulardynamik

KW - TiAl

KW - stacking fault energy

KW - generalized stacking fault energy

KW - GSFE

KW - Ab initio

KW - Molecular Dynamics

M3 - Master's Thesis

ER -