**4. Conclusions**

The investigation of four Zr-based glasses displaying diverse physical properties showed that the heat effects occurring in the supercooled liquid state and upon crystallization can well reproduced with Equation (1) using experimentally determined temperature dependences of shear moduli of the glass and maternal crystal. This equation is derived on the basis of the Interstitialcy theory and assumes that the heat effects in all temperature ranges take place due to the thermally activated change of the concentration of interstitial-type defects frozen-in from the melt upon glass production. A change of the defect concentration leads to a release or absorption of the total defect formation enthalpy constituting the physical reason for the heat effects both in the glassy state and upon crystallization.

**Author Contributions:** All authors equally contributed to this work. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was supported by the Russian Science Foundation under the gran<sup>t</sup> 20-62-46003.

**Conflicts of Interest:** The authors declare no conflict of interest.
