**4. Conclusion**

A detailed study of five iron-based amorphous alloys with the compositions Fe81Si4B13C2, Fe79.8Ni1.5Si5.2B13C0.5, Fe75Ni2Si8B13C2, Fe73.5Cu1Nb3Si15.5B7, and Fe40Ni40P14B6 revealed that the alloy behavior in terms of mechanism, thermodynamics, and kinetics of thermally induced microstructural transformations, as well as the functional properties, is significantly influenced by chemical composition of the alloy. The highest thermal stability among the studied alloys was observed for the Fe79.8Ni1.5Si5.2B13C0.5 alloy due to its optimal chemical composition. Crystallization changed alloy microstructure and morphology, making the alloys grainy and more porous, influencing the functional properties of the alloys. Crystalline α-Fe(Si) and Fe2B phases were observed to be the final crystallization products in all the alloys with Fe as the dominant component. Kinetic analysis of individual crystallization steps, performed after peak deconvolution, revealed around 25% lower apparent activation energy values of the Fe2B phase than those of the α-Fe(Si) phase, for most of the studied alloys, as a result of promoted Fe2B crystallization by formation of α-Fe(Si) grains and an enrichment of the amorphous matrix with boron. Relatively high stability of the studied alloys against crystallization was observed at room temperature in spite of thermodynamic metastability and kinetic metastability of amorphous materials, with its abrupt drop at increased temperatures.
