Dresden 2026 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 3: Mechanical Properties and Alloy Design I

MM 3.1: Talk

Monday, March 9, 2026, 10:15–10:30, SCH/A215

Mechanical Properties of Disordered Fe-Co Nanoparticles — •Yarden Nathan — Technion, Haifa, Israel

We synthesized Fe- 50 at.% Co nanoparticles (NPs) via solid-state dewetting of Fe-Co bilayers deposited on a sapphire substrate at the temperature of 900 *C followed by slow cooling. By employing X-ray diffraction and electron diffraction in transmission electron microscope (TEM) we demonstrated that the NPs are fully disordered α-FeCo body centered cubic (BCC) phase. We demonstrated that the size and orientations of the disordered BCC NPs can be controlled by varying their fabrication parameters. Most of the NPs were faceted single crystals with their top (110) facet oriented parallel to the substrate. The mechanical properties of the NPs were measured by employing in-situ micro compression tests in the scanning electron microscope (SEM). The near-theoretical strength of α-FeCo NPs was demonstrated. We propose that the fully disordered NPs behave similarly to the defect-free NPs of pure metals. The plasticity of these NPs is controlled by the dislocation nucleation requiring near-theoretical stress. This mechanism explains the near-theoretical strength and the distinct "smaller is stronger" size effect observed in this metastable phase.

Keywords: Solid State Dewetting; Order-Disorder; Nanoindentation; Strain; Coherency