Povarchuk V. Research of influence of ionization radiation on properties amorphous and nanocrystalline alloys based on Fe-Si-B system

Thesis deals with investigation of the influence of various radiation fields on either amorphous or nanocrystalline films of Fe-Si-B alloys. Particularly, both electron and gamma irradiations were applied to study of structure and magnetic properties of amorphous ribbons while gamma irradiation was used for research on magnetic properties of nanocrystalline alloys. It is shown, that dynamics of changes of the structural factor for amorphous Fe-Si-B alloys under electron and gamma irradiation are qualitatively identical. Two mechanisms of irradiation influence on structure of amorphous metal alloys are offered: radiation-enhanced relaxation and disordering. It is found, that amplitude for the first peak of the structural factor and direction of its changes, Curie temperature and temperature of crystallization of Fe-Si-B amorphous alloys essentially depend on concentration of silicon and boron in these alloys. It is shown, that difference in influence of irradiation on the short range ordering and crystallization in Fe-Si-B amorphous alloys can result from various mechanisms radiation-enhanced diffusion of silicon and boron atoms. It is established, that doping of Fe-Si-B amorphous alloys with nickel and molybdenum results in reduction of sensitivity of the structural factor, Curie temperatures, temperature of crystallization to radiation fields while the behavior of magnetic permeability is opposite. The qualitative model on influence of doping with these elements on radiation-enhance structural changes in Fe-Si-B alloys is offered. It is shown, that the electron irradiation results in the further crystallization of Fe-Si-B amorphous-crystal alloy followed crystals growth. It is established, that sensitivity of magnetic characteristics Fe-Si-B nanocrystalline alloys is smaller, than that for amorphous alloys. It is shown, that changes of magnetic characteristics of nanocrystalline alloys under irradiation are originated to structural changes in their amorphous matrix. It is shown, that radiation processingcan be applied as a way to change the magnetic characteristics of Fe-Si-B amorphous and nanocrystalline alloys. Key words: amorphous alloys, nanocrystalline alloys, Fe-Si-B, short range ordering, magnetic properties, electron irradiation, gamma irradiation, heat treatment, doping.