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KFM: Fachverband Kristalline Festkörper und deren Mikrostruktur

KFM 20: Structurally and Chemically Complex Alloys (joint session MM/KFM)

KFM 20.3: Talk

Wednesday, March 20, 2024, 17:45–18:00, C 230

Mechanical Alloying of High-Entropy Alloys: Insights from Molecular Dynamics Simulations — •Marie Charrier, Yulia Klunnikova, and Karsten Albe — Technical University of Darmstadt, Materials Modelling Division, Otto-Berndt Straße 3, 64206 Darmstadt, Germany

Mechanical alloying is a promising technique for producing high-entropy alloys. In this work, we explore intermixing processes and the formation of the solid solution starting from principal elements Co, Fe, Ni, Cr and Al in their respective lattice structures.

Severe plastic deformation is mimicked in Molecular Dynamics simulations by cyclic compressive loading of nanocrystalline samples inducing a quasi-hydrostatic stress state. The influence of grain orientation, grain size and temperature on structural evolution and chemical mixing is investigated. The structural and chemical complexity is increased by varying interfaces (from planar, bicrystalline to multiple, randomly oriented grains) and the number of components, respectively.

Independent of the starting configuration, we observe grain refinement and an HCP/BCC-FCC phase transformation within a few cycles, while chemical homogeneity is reached only at higher strains. These processes strongly depend on temperature and grain size, while the grain orientation plays a minor role. The final structures exhibit a large number of defects, in agreement with experimental observations. In general, the results provide atomic level insights into the mechanisms of mechanical alloying.

Keywords: high-entropy alloys; mechanical alloying; phase transformation; complex concentrated alloys; molecular dynamics