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DY: Dynamik und Statistische Physik
DY 46: Poster
DY 46.21: Poster
Donnerstag, 30. März 2006, 16:00–18:00, P1
Testing a cooperative shear model for bulk metallic glasses using ultrasonic measurement techniques — •Annelen Kahl1, Mary Laura Lind2, Stefan Buschhorn1, Jörg Hachenberg1, William L. Johnson2, and Konrad Samwer1 — 11. Physikalisches Institut, Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany — 2138-78 Keck Laboratory, California Institut of Technology, Pasadena, California 91125, USA
The mechanical and rheological properties of metallic glasses and super cooled liquids can be explained with a cooperative shear model [1]. These material properties can be deduced from inherent states in a potential energy landscape described for example by an extended Frenkel-like potential. The model explains a universal relation between the maximum resolved shear stress and the shear modulus. Furthermore a prediction for the temperature dependence of the shear modulus is given. By isothermally annealing a sample for different times, the as-prepared sample can be transferred to equilibrium states of various corresponding fictive temperatures. The shear modulus for samples in different annealing states is measured to interpolate the equilibrium line. Using ultrasonic sound waves we determine the acoustic velocities for different annealing times by measuring the sample length and the travel time of a high frequency pulse propagating through the sample. From the sound velocity and the density of the samples the shear modulus can be determined. We acknowledge SFB 602, TP B8 for financial support.
[1] W.L. Johnson, K.Samwer, PRL95, 195501(2005)