Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 22: Poster session I

MM 22.30: Poster

Montag, 20. März 2017, 19:00–20:00, P4

Grain boundary and triple junction segregation: Comparison between atom probe experiments and atomistic simulations — Rüya Duran, Daniel Beinke, •Sebastian Eich, and Guido Schmitz — Institut für Materialwissenschaft, Universität Stuttgart

In nanocrystalline materials, the volume fractions of grain boundaries (GBs) and triple junctions (TJs) gain significance, justifying these defects as a major research topic. Excess solute segregation at those defects generally reduces the free energy of the system and may inhibit grain growth and lead to stabilization of nanocrystalline materials.

Atom probe tomography (APT) is a state-of-the-art technique with nanometer accuracy in order to obtain 3D information of the spatial chemical distribution, allowing conclusions about GB segregation amplitude and GB compositional width.

However, both the field evaporation process in APT experiments and the reconstruction algorithm eo ipso imply artifacts in the reconstructed sample, e.g. drastic differences of atomic densities in the GBs as compared to the bulk.

By comparing experimentally investigated two-component nano-sized samples with realistic computer-simulated tricrystals, subjected to subsequent simulated evaporation, we reveal influences of the actual evaporation process on the reconstructed tip. Density fluctuations can directly be linked to different evaporation fields, which result from structural effects (e.g. different bonding in GBs) and/or different chemical species.