Influence of Heat Treatment on the Microstructure of Fe70Mo5Cr4Nb6B15 Alloy

The paper presents the results of microstructure and magnetic structure studies for amorphous Fe70Mo5Cr4Nb6B15 alloy in the form of ribbons of about 20 mu m in thickness. From X-ray diffraction and the Mossbauer spectroscopy the phase composition of the samples in the as-quenched state and after the thermal heat treatment are determined. From these studies it has been stated that the alloys in the as-quenched state are fully amorphous. X-ray diffraction studies show that in Fe70Mo5Cr4Nb6B15 alloy subjected to the annealing at 800 K for 30 min the crystalline Cr12Fe36Mo10 phase appears. Moreover, it has been found that the Mossbauer spectra of the alloys in the as-quenched state and after annealing in the wide temperature range has asymmetric doublets shape which is characteristic of paramagnetic materials. On the basis of the Mossbauer studies, it was found that the Cr12Fe36Mo10 phase is a paramagnetic because in the Mossbauer spectrum of heat-treated samples there are no components from any ferromagnetic crystalline phase.