**4. Conclusions**

A comparative study of the processes of devitrification of Zr55Cu30Al15Ni5 bulk alloy under heat treatment and deformation has been carried out.

The activation energy of crystallization, determined by the Kissinger method, is 278 kJ/mol.

It has been shown that different crystalline phases are formed during crystallization under heating and deformation. At the first crystallization stage, the metastable phase with a hexagonal structure (lattice of space group P63/mmc with the parameters a = 8.66 Å, c = 14.99 Å) is formed under heat treatment. When the temperature rises, the metastable phase decays with the formation of stable crystalline phases. The well-known crystalline Zr2Cu phase with the lattice of space group Fd3m is formed during crystallization under the action of deformation.

It has been determined that during deformation, nanocrystals are formed primarily in the subsurface regions of the samples. The nanocrystal size is several nanometers.

**Author Contributions:** Conceptualization, A.A.; sample preparation, D.G.; X-ray diffraction experiments, G.A. and B.G.; deformation, heat treatment, A.D. and B.M.; electron microscopy study, A.A., E.P. and D.M.; DTA experiments, I.S.; all authors analyzed the data, discussed the results and wrote the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** Russian foundation for Basic Research (partially).

**Acknowledgments:** The work was partially supported by RFBR (grants 19-03-00355 and 20-08-00497).

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