Berlin 2008 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 27: Liquid and Amorphous Metals II
MM 27.3: Vortrag
Mittwoch, 27. Februar 2008, 16:15–16:30, H 0107
Study of complex elastic moduli of metallic glasses during relaxation processes and in confined geometry — •Dennis Bedorf1, Thomas Koeppe1, Konrad Samwer1, and Ranko Richert2 — 1I. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2Department of Chemistry and Biochemistry, Arizona State University, Tempe AZ 85287- 1604, USA
Measuring the complex elastic constants in a metallic glass enables us to study relaxation processes especially during the first heating run of a glass. The first increase of storage modulus far below the alpha process can be linked to a beta process. The different rate dependence of both can be used to estimate the merging temperature [1]. Dynamical heterogeneities are known to have spatial dimension of several nm. To get experimental data of loss spectra in confined geometry we measure thin films of PdCuSi on a double-paddle-oscillator (DPO). Change of resonance frequency and Quality factor are used to determine the complex shear modulus of the film. Preparation and characterizations were performed in situ under UHV conditions. Precise measurements of early relaxations above RT were also performed by using thin cantilevers of a metallic glass. All results are discussed in the model of a potential energy landscape as described in [2]. This work was supported financially by DFG, SFB 602 and Leibniz Programm.
[1] J. Hachenberg et al., to be published
[2] J. S. Harmon, M. D. Demetriou, W. L. Johnson and K. Samwer, Phys. Rev. Lett. 99, 135502 (2007)