Hryhoryeva O. Magnetic effects during the phase transformations in iron-based alloys: Fe-B, Fe-Si-B, Fe-C

The thesis is devoted to establishing the nature of magnetic effects during the phase transformations in metastable iron-based alloys Fe-B, Fe-Si-B, Fe-C. The special method of analysis of magnetic characteristics is developed at heating amorphous alloys. The received parities connect experimentally changes of properties with changes of quantity of phases in alloys with nonequilibrium structure. It was established that sequence of phase transformations at heating of Fe-C alloys does nоt change in the interval of phases quantity change in this process. Phase transformations during the heating of amorphous alloys Fe-B, Fe-Si-B were studied. The differential thermomagnetic analysis and X-ray method were used. The equations that describe the magnetic effects were analysed. The temperature intervals of phase transformations were determined, the magnetic properties of the starting phase and of the phases that are formed during crystallization are determined. It was shown that increase of silicon and boron content improves stability of amorphous state, Curie point and crystallization interval and reduces the specific magnetization of amorphous alloys. Key words: phase transformations, magnetic effects, amorphous alloys, alloying elements, crystallization, magnetization, intervals of stability, enthalpy.