Thermodynamic quantities frozen·in upon vitrification of metallic alloys

Abstract

For a few glass-forming metallic systems whose specific heat is known for both the crystal and the liquid phase, together with the heat of fusion, the thermodynamic quantities trapped at the glass transition T _g have been computed by extrapolation of the liquid data. The difference in enthalpy ΔH _g is reasonably well approximated by the heat of crystallization, which is accessible to experiment. Attempts are made to express ΔS _g and ΔG _g as a function of ΔH _g. On the basis of the observation that ΔC _p is either linear with temperature or follows a formula recently proposed by Dubey and Ramachandrarao (1984), lower and upper limits are obtained. ΔS _g is shown to be proportional to ln(T _g/T ₂), as found for conventional glass formers (T ₂ is the temperature of vanishing excess entropy).