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Regensburg 2019 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 16: Methods in Computational Materials Modelling (methodological aspects, numerics)

MM 16.4: Talk

Tuesday, April 2, 2019, 11:00–11:15, H45

Atomistic Modelling of Early Stage Clusters In Al-Mg-Si alloys — •David Kleiven1 and Jaakko Akola1,21Norwegian University of Science and Technology, Trondheim, Norway — 2School of Chemical Technology, Aalto University, Aalto, Finland

Aluminium alloys are essential in a variety of industrial applications, including cars and aeroplanes. The mechanical properties, such as hardness and strength, depend heavily on the formation of beneficial precipitates from solute species. Interestingly, the precipitation process (and prior nucleation) can be manipulated via thermomechanical treatment. We apply the Cluster Expansion formalism as implemented in CLEASE (CLuster Expansioin in ASE) to construct a DFT-parametrised energy model for Al-Mg-Si alloys, which we further apply in finite temperature statistical simulations. Even though Al-Mg-Si is a common industrial alloy, the mechanisms behind the precipitation process are still not fully understood. In this contribution, the stable phases on the FCC lattice, which are important intermediates for needle-like precipitates, are identified with high accuracy (~5 meV/atom). We assess the role of various effects such as solute ordering and direction-dependent surface tension of solute clusters. Via this approach we obtain quantitative results for the thermodynamics of early stage clusters in Al-Mg-Si alloys which paves way for understanding the precipitation process at atomistic level.

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