The role of plasma FIB-SEM in the preparation of samples for in-situ heat treatment of Al-Mn-Cr-Zr based alloys for additive manufacturing in the synchrotron

Session

FIB Applications & EM Samples Prep Techniques in Physical Sciences

Authors

Vendulka Bertschova (3), Bharat Mehta (1), Isac Lazar (2), Lars Nyborg (1), Anders Mikkelsen (2), Martin Slama (4, 5)

Affiliations

1. Department of Industrial and Materials Science, Chalmers University of Technology
2. Division of Synchrotron Radiation Research, Department of Physics, Lund University
3. TESCAN Orsay Holding a.s.
4. TESCAN Orsay Holding a.s.,
5. Department of Mechanical engineering, Brno University of Technology

Keywords

Plasma FIB-SEM, Synchrotron, Sample preparation, Al-Mn-Cr-Zr based alloy 

Abstract text

The powder bed fusion-laser beam method is used for processing novel materials for additive manufacturing. This method was used for the preparation of aluminum-based materials with the possibility to control their microstructure and resulting properties. In this talk, we present the two variants from Al-Mn-Cr-Zr based alloy family prepared by the plasma FIB-SEM method for synchrotron experiments. Using in-situ synchrotron scanning X-ray fluorescence to map out the distribution of Mn, Cr, and Fe, we could show how different precipitates nucleate and grow in the material over time at elevated temperatures. The developed precipitates are responsible for a substantial hardness increase during post-printing annealing. Therefore, understanding the material behavior and precipitates formation when exposed to higher temperatures is a crucial step for material development in basic research and applied research. 

 

Sample preparation was a critical step for a successful synchrotron experiment. Plasma FIB-SEM was used to avoid the well-known problem of Ga segregating to grain boundaries in Al alloys when using conventional Ga FIB-SEM. Usage of the inert Xe+ ion in the Plasma-FIB-SEM ensured no chemical interference with the microstructural evolution at the grain boundaries. At the same time, Plasma FIB-SEM enabled the preparation of larger samples capturing a statistically representative number of grains with different sizes and orientations. The grain orientation and type were confirmed prior to the sample preparation by EBSD and EDS. The SEM contrast was used for precise navigation during the individual sample preparation. The cubic specimens for synchrotron investigations were FIB-prepared from a specific area of interest at a thickness of 1 µm and size 10 µm x 30 µm and 50 µm x 50 µm. The preparation process contains multiple preparation steps including transfer to the chips for subsequent in-situ heating experiments in the synchrotron.