THERMODYNAMIC PROPERTIES OF PD40NI40P20 IN THE GLASSY, LIQUID, AND CRYSTALLINE STATES

Bulk specimens of the easy glass-forming alloy Pd40Ni40P20 have been u ndercooled 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 perform ed in a commercial heat-flow differential calorimeter, covering for th e first time the entire undercooling regime of a liquid metal from the melting temperature down to the glass transition temperature. Based o n the measured specific heat data of the undercooled liquid and the cr ystalline state, the differences in the thermodynamic functions enthal py, entropy, and Gibbs free energy are determined in dependence on tem perature. The entropy balance yields a value of T0=500+/-5 K for the i deal glass transition temperature of this metallic system. The experim ental values are compared to the corresponding thermodynamic functions , derived from commonly applied Gibbs free energy approximations for t he undercooled liquid.