Regensburg 2013 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 15: Poster Session
MM 15.23: Poster
Montag, 11. März 2013, 18:00–20:00, Poster E
Cluster expansion study of Ni–Pt alloys — •Martin Leitner, David Reith, and Raimund Podloucky — Department of Physical Chemistry, University of Vienna
The Cluster expansion (CE) is a state-of-the-art tool for exploring the configuration space of multi-component systems with the accuracy of density functional theory (DFT) calculations. Based on the figure set of a converged CE Monte-Carlo (MC) simulations are performed in order to derive temperature dependent phase stabilities.
This CE+MC approach – as implemented in the UNCLE package [1] – is applied to study the Ni–Pt alloy system, for which the formation of ordered phases at low temperatures is under debate. DFT studies focussed on three ordered phases, namely NiPt3 and Ni3Pt with L12 structure and NiPt with L10 structure. A CE study predicted an additional stable Pt-rich phase of NiPt7 composition, which was not confirmed by recent DFT studies and experiment. A further DFT study predicted a Ni-rich Ni3Pt phase with D022 ordering to be energetically more favorable than the L12 structure.
Based on DFT calculations performed with VASP an extensive CE+MC study was done for the whole composition range. The results will be critically compared to the existing data. Furthermore, calculated short range order intensities are compared to very recent X-ray Photon Correlation Spectroscopy (XPCS) experiments in the Ni-rich regime.
Supported by FWF, project nr. F4110 (ViCoM).
[1] D. Lerch et al., Modelling Simul. Mater. Sci. Eng. 17 (2009), 055003