Evolution of the activation energy spectrum and defect concentration upon structural relaxation of a metallic glass determined using calorimetry and shear modulus data

We performed high precision shear modulus and calorimetry measurements on a model Pd-based glass subjected to different annealing treatments below the glass transition temperature T_g. Applying the Interstitialcy theory, we found that structural relaxation-induced heat release/absorption below and near T_g can be precisely described using shear modulus data confirming thus the generic relationship between the heat and elastic relaxation effects in metallic glasses. The same approach is used for the reconstruction of underlying activation energy spectra. It is found that the spectra derived from calorimetry and shear modulus data are very close. Integration of these spectra gives the change of the concentration of frozen-in defects and its absolute value for different stages of structural relaxation.