VITRIFICATION CLOSE TO THE KAUZMANN POINT OF EUTECTIC AU-PB-SB ALLOYS

Measurements of the thermodynamic and kinetic properties in the fully relaxed undercooled liquid regime near the glass transition temperatur e of Au-Pb-Sb alloys show that the measured glass transition temperatu re extrapolated to zero heating rate corresponds to the isentropic (Ka uzmann) temperature T(go) The slowing down of relaxation processes aro und the ideal glass transition temperature as well as the temperature dependence of the viscosity can be described by a Vogel-Fulcher law wi th the same critical temperature, the Kauzmann temperature. The experi mental results suggest that for Au-Pb-Sb alloys the glassy state can b e approached as a truly metastable state with an activation barrier of about 0.02 eV, in comparison with 1.5 eV for crystallization, suggest ing a second-order phase transition with an underlying critical point as predicted by scaling theories.