Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 47: Poster Session II

MM 47.41: Poster

Wednesday, March 14, 2018, 18:30–19:45, Poster C

XAFS on Al-alloys: an investigation of early clustering and precipitation states — •Frank Lotter, Danny Petschke, Elischa Bläss, and Torsten Staab — University Wuerzburg, Dep. of Chemistry, LCTM Roentgenring 11, 97070 Wuerzburg, Germany

X-ray absorption spectroscopy (XAS) provides a powerful tool to probe the local atomic surroundings of the absorbing element. Therefore the energy of the incoming X-ray beam is varied around the absorption edge of the specific element. The excited atom becomes origin of a spherical photo wave which interferes with neighboring atoms by multiple scattering. This results in an oscillating spectrum, the so called Fine Structure, giving information about the local structure around the probed atom.

The Al-Cu system offers a basis for alloys (Al-Cu-Mg, Al-Cu-Li, Al-Si-Cu) with important technological applications in the automotive and aerospace sector.

Differential Scanning Calorimetry (DSC) was used to confirm ageing states where one precipitate phase clearly dominates. Thus different reference states were created which then could be investigated by XAS at the Cu K-edge. Furthermore, in situ natural ageing experiments were conducted directly after quenching by using the energy dispersive XAS technique, which allows for very short measuring times, to emphasize the method's sensitivity for small changes in the local atomic configuration surrounding the Cu atoms.