EN
The process of nanocrystalline phase formation, affecting magnetic properties, in amorphous Fe_{78}Si_{8}B_{14}, Fe_{76}Al_{2}Si_{8}B_{14}, Fe_{76}Cr_{2}Si_{8}B_{14} and Fe_{76}Mo_{2}Si_{8}B_{14} alloys has been studied in the paper. Investigations have been carried out using the electrical resistivity method, magnetic methods, transmission electron microscopy and X-ray diffraction. A nanocrystalline phase in the amorphous matrix has been obtained by isochronous or isothermal vacuum annealing. Phase composition of samples has been determined directly after manufacturing and after crystallization annealing on the basis of X-ray diffraction and electron diffraction. Transmission electron microscopy was used to determine phase morphology, dimensions of formed nanocrystalline phase and transition phase. Alloying elements have been found to affect changes of magnetic properties in amorphous and nanocrystalline states. For Fe_{76}Mo_{2}Si_{8}B_{14} alloys a significant increase in crystallization temperature, making difficult nanocrystalline phase growth and increase in thermal stability of magnetic permeability have been observed.