Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 32: Poster TU B (Symposium Tomographic Methods in Materials Research M-32.32-55)

M 32.10: Poster

Montag, 7. März 2005, 14:30–16:30, Poster TU B

Mechanical spectroscopy of Zr65Al7.5Cu27.5 thin films and first evidence for an excess-wing in metallic glasses — •Peter Rösner and Konrad Samwer — I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen

The double-paddle oscillator is used for the study of mechanical properties of thin amorphous Zr65Al7.5Cu27.5-films in the tempe-rature range from 300 to 650 K under ultra high vacuum conditions. The oscillator is driven in its secondary torsional eigenmode at about 5.4 kHz and the temperature dependence of the complex shear modulus of the film is measured. At temperatures above the glass transition, the loss modulus can be mathematically described by a Havriliak-Negami function. In the vicinity of the glass transition, our data clearly differ from this mathematical model. The temperature dependence of the mechanical loss modulus is very similar to the dielectric loss modulus of many other glass forming materials, where the deviation from the viscous alpha-process is described with an excess wing. Our experimental results give rise to the assumption that there exists a wing also in amorphous metals and could therefore be a universal property of glasses. One interpretation for the wing is to postulate density fluctuations and dynamic heterogeneities. Cooperative movement of groups of atoms that are called clusters and formed in the vicinity of the glass transition lead to a deviation of the alpha-process that is due to single-atom movement. The authors would like to thank P. Lunken-heimer and A. Loidl for many stimulating discussions. This work was supported by the Deutsche Forschungsgemeinschaft SFB 602, B8 and the Graduiertenkolleg 782.