Density and Enthalpy Relaxation Behavior in a Bulk Pd₄₀Ni₄₀P₂₀ Metallic Glass

Abstract

The kinetics of structural relaxation in a Pd40Ni40P20 bulk metallic glass was investigated by the volume relaxation due to density experiments and the enthalpy relaxation due to specific heat experiments. A two-step relaxation process was found in the volume relaxation, while the enthalpy relaxation seemed to be one-step relaxation process with a spectrum of relaxation times. First-step volume relaxation only in as-quenched glass was the process with a spread of relaxation times at lower relaxing temperature, while a Debye-type relaxation behavior was observed at higher temperature near Tg and in pre-annealed glass. The comparison of the kinetics of volume and enthalpy relaxations at the same temperature showed a disagreement with the prediction of free volume theory.