Fachbereich 11 - Physik
Institut für Materialphysik
Diffusion in Metals, Intermetallics, Silicides, Quasicrystals and Metallic Glasses

Diffusion in bulk metallic glasses and supercooled melts

Metallic glasses are of considerable technological importance. From a fundamental point of view, metallic glasses are the paradim of dense randomly packed structures. Since the discovery of bulk metallic glasses it has become possible to measure atomic diffusion also in the supercooled liquid state and to study the dynamics of the liquid-to-glass transition in metallic systems. In a joint effort by several experts within a Schwerpunktprogramm of the DFG we reviewed experimental results and computer simulations on diffusion in metallic glasses and supercooled melts. Experimental techniques, effects of structural relaxation, temperature dependence, atom-size dependence, pressure dependence, isotope effect, radiation effects and molecular dynamic simulations of diffusion were considered. It is shown that diffusion in metallic glasses is significantly different from diffusion in crystalline metals and involves thermally activated, highly collective processes. Similar thermally activated collective processes were also found to mediate diffusion in the supercooled liquid state well above the caloric glass transition temperature. This strongly supports the mode-coupling scenario of the glass transition, which predicts an arrest of liquid-like flow already at a critical temperature well above the caloric glass transition.

Drittmittelgeber:

Deutsche Forschungsgemeinschaft (Schwerpunktprogramm: Unterkühlte Metallschmelzen - Phasenselektion und Glasbildung')

Beteiligte Wissenschaftler:

Prof. F. Faupel (Universität Kiel), Prof. Dr. W. Frank (MPI für Metallforschung, Stuttgart), Dr. M.-P. Macht (HMI Berlin), Prof. Dr. H. Mehrer (Universität Münster), Dr. V. Naundorf (HMI Berlin), Dr. K. Rätzke (Universität Kiel), Dr. H. R. Schober (FZ Jülich), Prof. S. K. Sharma (Malaviya Regional Engineering College, Jaipur, Indien), Prof. Dr. H. Teichler (Universität Göttingen)

Veröffentlichungen:

Faupel, W. Frank, H.-P. Macht, H. Mehrer, V. Naundorf, K. Rätzke, H. Schober, S. Sharma, H. Teichler: Diffusion in metallic glasses and supercooled melts, Review of Modern Physics 75, 237 - 280 (2003)