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MM: Fachverband Metall- und Materialphysik
MM 4: Microstructure and Phase Transformations - Characterization
MM 4.1: Vortrag
Montag, 16. März 2020, 10:15–10:30, IFW B
Spatial correlations between strengthening phases in hardenable aluminum alloys — •Viktor Wessely1, Robin Schäublin1, Stephan S. A. Gerstl1,2, Stefan Pogatscher3, Peter J. Uggowitzer1, and Jörg F. Löffler1 — 1Laboratory of Metal Physics and Technology, Department of Materials, ETH Zurich, 8093 Zurich, Switzerland — 2Scientific Center for Optical and Electron Microscopy, ETH Zurich, 8093 Zurich, Switzerland — 3Nonferrous Metallurgy, Montanuniversitaet Leoben, 8700 Leoben, Austria
We focus on a new generation of hardenable aluminum alloys based on the concept of high-strength Al–Sc alloys that form coherent Al3X L12-structured precipitates. Suitable candidates other than Sc are rare-earth or transition metals, such as Er, Zr, Hf or Yb, which have been shown to strengthen the material while simultaneously providing improved high-temperature stability. In this study we deployed thermodynamic and kinetic modeling to design alloys and their heat treatments, with subsequent mechanical and microstructural characterization. The dispersoids form as a coherent ordered phase within the fcc matrix. Studying their evolution in Al–Mg–Zn alloys with < 1 wt.% Er and Zr, we find that the Al3X dispersoid phase has a significant impact on the alloys’ hardening characteristics. Detailed insights into the microstructure are obtained by a multi-scale analysis based on high-end transmission electron microscopy (TEM), atom-probe tomography (APT) and molecular dynamics (MD) simulations. A key for the rational design of multi-phase strengthened aluminum alloys lies in the spatial correlation between the dispersoids and the precipitate phase.