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MM: Fachverband Metall- und Materialphysik

MM 28: Mechanical properties

MM 28.2: Vortrag

Donnerstag, 20. März 2025, 10:30–10:45, H23

Atomistic Modelling of Solid Solution Strengthening in the Mg-Al-Ca System — •Erik Bitzek and Marvin Poul — MPI SusMat, Düsseldorf, Germany

Solid solution strengthening is one of the most important strengthening mechanisms for engineering alloys. It is caused by solutes impeding the glide of dislocations and is therefore best studied using atomistic simulations. While the interaction strength of individual solute atoms with dislocations in Mg has been well-studied with density functional density (DFT) calculations, the combined impact of multiple solute species on dislocation glide has not been extensively investigated. Furthermore, the prediction of the critical resolved shear stress requires additionally a statistical treatment and a continuum elastic model for the dislocation line.

Here we present atomistic simulations of basal dislocations gliding in Mg with different concentrations of Al, Ca, and mixtures of Al and Ca. These large-scale simulations were enabled by a newly-developed machine learning interatomic potential that allows for near-DFT accuracy. Using MD/MC simulations of different heat treatments, we show that Al-Ca clusters can form, which influence the solid solution strengthening by reducing the concentrations of individual solutes and through an antagonistic effect of Al and Ca on the stress field of these clusters.

Keywords: Solid solution strengthening; Mg Alloys; Dislocations; Machine learning interatomic potentials; Atomistic simulations