On the nature of the excess internal energy and entropy of metallic glasses

The excess internal energies $\Delta U_Q$ and excess entropies $\Delta {{S}_{Q}}$ of ten metallic glasses with respect to their parent crystalline states are determined from calorimetric studies. The elastic energy $\Delta U_{\mathrm{el}}$ of the subsystem of interstitial defects responsible for relaxation phenomena in metallic glasses according to interstitialcy theory is calculated within this theory using the measured high-frequency shear modulus. It is established that the quantities $\Delta U_Q$ and $\Delta U_{\mathrm{el}}$ coincide with each other within an accuracy of no less than $10$–$15\%$. It is concluded that the excess internal energy and excess entropy of metallic glasses are due primarily to the elastic energy of the subsystem of interstitial defects. The dissipation of this energy into heat under heating reduces $\Delta U_Q$ and $\Delta S_Q$ to zero because of the complete crystallization. The entropy per defect is estimated from calorimetric data as $S_d\approx20{-}30k_B$, which is characteristic of interstitial defects.