NANOCRYSTALLIZATION OF AMORPHOUS ALLOYS UNDER THE ACTION OF IRRADIATION WITH ARGON IONS.

The purpose of the research is to analyze the possibility of obtaining an amorphous nanostructured state from the original amorphous state by ion irradiation. The processes of phase formation in the Fe75Mo5Si6B14 amorphous alloy under the influence of argon ion irradiation were investigated using the methods of highly sensitive dilatometry, microhardness measurements, and electron microscopy. The surface treatment of the amorphous alloy with argon ions was carried out at a voltage on the anode of 1 kV and a current through the sample of 1 mA. The surface morphology of the amorphous alloy treated with argon ions was studied under a LensSEI scanning electron microscope. The structure of amorphous alloys is characterized by the presence of frozen-in crystallization centers. It was found that the phenomenon of nanocrystallization is not observed during exposure to ion irradiation for up to 30 minutes. This is explained by the fact that, as a result of ion irradiation, the local temperature on the surface of the sample rises and reaches such values, at which, according to the thermodynamic theory of thermal stability, the frozen centers of crystallization can dissolve in the amorphous matrix. When the ion irradiation time of the source alloy is increased to 45 minutes, a decrease in thermal stability of 25 °C and an increase in microhardness of 8.2% are observed, therefore, the alloy is strengthened. This indirectly indicates the formation of an amorphous-nanocrystalline state in the alloy. Structural changes are also confirmed by the results of studies of the amorphous alloy surface morphology by scanning electron microscopy. After irradiation, both the number of crystal nuclei and their average size increase significantly (from 20 nm in the source alloy to 65 nm in the irradiated one). The changes in the number and size of crystal nuclei are explained by the fact that at an irradiation time of 45 minutes, the temperature in the regions of the ion tracks reaches threshold values and thermodynamic conditions are created for the growth of frozen crystallization centers. [ABSTRACT FROM AUTHOR]