SKM 2023 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 40: Mechanical Properties and Allloy Design

MM 40.4: Vortrag

Donnerstag, 30. März 2023, 16:30–16:45, SCH A 251

Observation of in-plane oriented Guinier-Preston zones in Al-Cu — •Johannes Berlin, Tobias Stegmüller, and Ferdinand Haider — Universität Augsburg, Deutschland

Known for a long time, the first metastable precipitates forming in Al-Cu alloys during natural ageing are the so-called Guinier-Preston zones (GPZ), platelets of Cu on {100} planes of only one atomic layer thickness. With the development of aberration corrected (S)TEMs, direct observation and imaging of these platelets was possible, but with the restriction, that only edge view was possible. Using a Cs-probe corrected scanning transmission electron microscopy with HAADF detector (DF-STEM), a single Cu atom in a Al column results in sufficient contrast to the neighbouring columns. In sufficiently thin samples, planar zones then lead to theoretically forbidden reflections of type {110} in the fourier transformed image, since only half of the columns in the GP zone contain a Cu atom. Thus, fourier filtering of such an image with only these forbidden reflections allows to observe GP Zones in a plan-view. The average size, shape and density of the GP-zones was determined for different aging times, and STEM image simulations using the software package DrProbe support this interpretation.