Dresden 2017 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 56: Topical session: Dynamics, relaxation and deformation in deeply supercooled metallic liquids and glasses - kinetic transitions

MM 56.1: Topical Talk

Donnerstag, 23. März 2017, 10:15–10:45, IFW A

Anomalous atomic motion in metallic glasses revealed by coherent X-rays — •Beatrice Ruta — Institute of Light and Matter, Lyon 1 University-CNRS, France.

Metallic glasses display outstanding thermal, mechanical and chemical properties, which make them forefront materials for technological applications in many diverse fields such as medicine, environmental science and engineering. Their widespread use is, however, limited by their lack of stability over time due to ongoing relaxation processes and physical aging. X-ray Photon Correlation Spectroscopy (XPCS) has recently emerged as the very only technique able to measure the atomic motion in both crystalline and amorphous materials. By collecting series of diffraction data with coherent X-rays, XPCS measures the particle dynamics though the temporal evolution of the intensity fluctuations in the generated speckles patterns. Measurements on metallic glasses have revealed the existence of microscopic structural rearrangements, which cannot be explained by any current theory. In these systems, the dynamics evolves from a diffusive atomic motion in the supercooled liquid phase to a stress-dominated dynamics in the glass, characterized by a complex hierarchy of aging regimes. By combining dynamical (XPCS) and structural (XRD) studies we have been able to quantitatively link for the first time this anomalous atomic motion to microscopic structural mechanisms usually observed in diffraction studies, providing a broader unique view of the glassy state.