Berlin 2015 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 33: Structural Materials I: Phase Stability and Mechanical Properties
MM 33.2: Vortrag
Mittwoch, 18. März 2015, 10:30–10:45, TC 010
Analysis of the thermodynamic phase stability in the Al-Sc system using first principles methods — •Ankit Gupta1, Biswanath Dutta1, Tilmann Hickel1, Jörg Neugebauer1, Yulia Buranova2, and Sergiy Divinski2 — 1Max-Planck-Institut für Eisenforschung GmbH, D-40237 Düsseldorf, Germany — 2Institute of Materials Physics, University of Münster, D-48149 Münster, Germany
Driven by the need to achieve high strength materials with reduced weight, Al-Sc alloys have received considerable attention in the last couple of decades owing to their superior mechanical and anti-recrystallization behaviour. These improved properties critically depend on Al3Sc particles that precipitate out from Sc supersaturated solid solution. In experiment, their shape, distribution and morphology show a remarkable variation depending on composition and mechanical load, which has not yet been understood. In this work, we therefore investigate the thermodynamic phase stability of this alloy system within a first-principles based approach with a focus on the Al rich corner of the binary phase diagram. The temperature dependence of the Sc solubility in Al is calculated as an outcome of a competition between the free energies of formation of the dilute solvents and the ordered precipitate phase within the quasi-harmonic approximation. Our results for the thermodynamic and elastic properties of the Al3Sc phase additionally confirm the experimental finding of coherent precipitates. The investigations are extended towards kinetic Monte-Carlo simulations of the precipitation kinetics in terms of TTT diagrams for the precipitate formation.