Thermodynamic properties of Pd40Ni40P20 in the glassy, liquid, and crystalline states

Abstract

Bulk specimens of the easy glass‐forming alloy Pd40Ni40P20 have been undercooled consistently into the glassy state at cooling rates as low as 10 K/min applying the melt‐fluxing technique in boron trioxide. Due to this low cooling rate, heat capacity measurements could be performed in a commercial heat‐flow differential calorimeter, covering for the first time the entire undercooling regime of a liquid metal from the melting temperature down to the glass transition temperature. Based on the measured specific heat data of the undercooled liquid and the crystalline state, the differences in the thermodynamic functions enthalpy, entropy, and Gibbs free energy are determined in dependence on temperature. The entropy balance yields a value of T 0=500±5 K for the ideal glass transition temperature of this metallic system. The experimental values are compared to the corresponding thermodynamic functions, derived from commonly applied Gibbs free energy approximations for the undercooled liquid.