Regensburg 2019 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 27: Methods in Computational Materials Modelling (methodological aspects, numerics)
MM 27.3: Vortrag
Mittwoch, 3. April 2019, 15:30–15:45, H44
Understanding the thermodynamics and kinetics of precipitate formation in Al-Sc-Zr alloys — •Ankit Gupta1, Yulia Buranova2, Vladislav Kulitcki2, K. Li3, Yong Du3, Biswanath Dutta1, Tilmann Hickel1, Jörg Neugebauer1, Gerhard Wilde2, and Sergiy V. Divinski2 — 1Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany — 2Institute of Materials Physics, University of Münster, Germany — 3Institute for Materials Microstructure, Central South University, Changsha, China
The thermal stability of Al-based alloys is enhanced typically by improving the coarsening resistance of second phase particles. A classic example is the addition of Zr to Al-Sc alloys where the Zr segregation at particle-matrix interfaces thermally stabilizes the Al3Sc particles. Our experiments performed under varying processing conditions result in a rich microstructure characterized predominantly by two types of second phase Al3(Sc,Zr) particles: one with uniform distribution of Sc and Zr and the other with a Sc-rich core and Zr-rich shell. The chemically heterogeneous core-shell structure exhibits an anisotropic Zr distribution along different orientations of precipitate interfaces. Using DFT based calculations, we quantify this sensitive interplay between the bulk and interfacial thermodynamics causing the observed two-phase microstructure. The computed mixing enthalpy trends predict homogeneously distributed Sc and Zr on the Sc-sublattice to be the thermodynamically stable configuration. The relevance of interfacial segregation and solute interactions in explaining the chemical anisotropy and the subsequent growth of core-shell structures are shown.