Interrelationship between heat release and shear modulus change due to structural relaxation of bulk metallic glasses

•Kinetics of structural relaxation is controlled by shear modulus relaxation.•Heat release upon structural relaxation is proportional to shear modulus change.•Released heat per relaxation unit equals to interstitialcy formation enthalpy.

Within the framework of the Interstitialcy theory it is shown that the amount of heat released during structural relaxation of metallic glasses must be proportional to the room-temperature change of the shear modulus. This prediction is verified by using experimental data taken on seven bulk metallic glasses. It is found that the kinetics of exothermal heat flow upon structural relaxation is determined by shear modulus relaxation. The released heat per one kinetic relaxation unit (“defect”) for all glasses practically coincides with the “defect” formation enthalpy calculated using the Interstitialcy theory providing further support for the description of structural relaxation on the basis of this approach.