On the Nature of the Excess Internal Energy and Entropy of Metallic Glasses

The excess internal energies ΔU_Q and excess entropies ΔS_Q of ten metallic glasses with respect to their parent crystalline states are determined from calorimetric studies. The elastic energy ΔU_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 ΔU_Q and ΔU_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 ΔU_Q and ΔS_Q to zero because of the complete crystallization. The entropy per defect is estimated from calorimetric data as S_d ≈ (20–30)k_B, which is characteristic of interstitial defects.