SKM 2023 – wissenschaftliches Programm

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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 9: Microscopy and Tomography with X-ray Photons, Electrons, Ions and Positron

KFM 9.10: Vortrag

Mittwoch, 29. März 2023, 12:15–12:35, POT 106

Correlation of Mechanical Stress and the Positron Lifetime in Aluminum Alloys — •Lucian Mathes¹, Vassily Vadimovitch Burwitz¹, Adrian Langrehr¹, Maik Butterling², Maciej Oskar Liedke², Eric Hirschmann², Andreas Wagner², and Christoph Hugenschmidt¹ — ¹Heinz Maier-Leibnitz Zentrum, TU München — ²Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiation Physics

Positron annihilation lifetime spectroscopy (PALS) is a sensitive technique to analyze the type and concentration of lattice defects on an atomic level. We applied ex-situ and in-situ PALS to plastically deformed technical Al and Al alloys. Thereby we are able to observe the creation and evolution of stress-induced defects in the region beyond the elastic Hook regime of the specimen. The in-situ bulk measurements were performed using a β⁺ emitter in a new experimental setup combining tensile tests and PALS at TUM that also allows for investigation of the reversible elastic deformation of samples. The depth-dependent positron lifetime was measured ex-situ at the accelerator-based positron source MEPS at ELBE. For each sample we recorded the tensile stress, and the corresponding stress-strain curves. This allows us to determine the relation between applied stress, strain and mean positron lifetime. Within this contribution, we also discuss the evolution of the defect population with increasing deformation by examining the intensity change of the different positron lifetime components found in the PALS spectra.