**Ab initio and atomistic study of generalized stacking fault energies in
Mg and Mg-Y alloys**

Z Pei and LF Zhu and M Friak and S Sandlobes and J von Pezold and HW Sheng and CP Race and S Zaefferer and B Svendsen and D Raabe and J Neugebauer, NEW JOURNAL OF PHYSICS, 15, 043020 (2013).

DOI: 10.1088/1367-2630/15/4/043020

Magnesium-yttrium alloys show significantly improved room temperature
ductility when compared with pure Mg. We study this interesting
phenomenon theoretically at the atomic scale employing quantum-
mechanical (so-called ab initio) and atomistic modeling methods.
Specifically, we have calculated generalized stacking fault energies for
five slip systems in both elemental magnesium (Mg) and Mg-Y alloys using
(i) density functional theory and (ii) a set of embedded-atom-method
(EAM) potentials. These calculations predict that the addition of
yttrium results in a reduction in the unstable stacking fault energy of
basal slip systems. Specifically in the case of an I-2 stacking fault,
the predicted reduction of the stacking fault energy due to Y atoms was
verified by experimental measurements. We find a similar reduction for
the stable stacking fault energy of the *11 (2) over bar2*< 11 (2) over
bar3 > non-basal slip system. On the other hand, other energies along
this particular gamma-surface profile increase with the addition of Y.
In parallel to our quantum-mechanical calculations, we have also
developed a new EAM Mg-Y potential and thoroughly tested its
performance. The comparison of quantum-mechanical and atomistic results
indicates that the new potential is suitable for future large-scale
atomistic simulations.

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