Tomography in Analytical Transmission Electron Microscopy of Nanomaterials
A.Orthacker1, G. Haberfehlner1, J. Tändl2, M.C. Poletti2 and G. Kothleitner1,3
1. Graz Centre for Electron Microscopy, 2. Institute for Materials Science and Welding, 3. Istitute for Electron Microscopy and Nanoanalysis
13:20 - 13:40 Thursday 23 October 2014 Rechbauerstrasse 12, HSII The importance of light materials with a high mechanical stability is constantly increasing, as these materials for instance enable energy efficient and safe transport, like in aviation. The material studied in this work is an alloy containing scandium and zirconium rich nanoparticles, which increase the material’s mechanical resistance, when embedded in the aluminium-magnesium matrix.
Transmission electron microscopy (TEM) and analytical scanning transmission electron microscopy (STEM) were used to investigate the material at the nanoscale. First investigations revealed that the sizes and exact chemical compositions of the nanoparticles can vary, depending on the ageing process. It was confirmed that the crystal structure of the nanoparticles, with the basic composition Al3Sc, coherently matches the crystal structure of the matrix. Furthermore, upon longer aging, these particles can even exhibit a weak core-shell structure. This is because more Zr atoms occupy Sc lattice sites in the shell due to the slower diffusion of Zr - compared to Sc – in the matrix.
The integrative character of the signal acquired through transmission might hide important structural details of the material, relevant for its properties. Those details can be revealed by using electron tomography, where the data is acquired at different tilt angles and, after alignment, reconstructed to form a full 3D model of the investigated material. The combination of both techniques, analytical STEM and tomography, offers a more complete understanding of the material’s structure and composition. Material aspects as well as tomography and STEM related procedures and developments shall be presented.
Acknowledgements: We thank the Austrian Cooperative Research Facility, the European Union (7th Framework Programme: ESTEEM2) and the Austrian Research Promotion Agency FFG (TAKE OFF project 839002) for funding.
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