KATARZYNA BLOCH, MATEUSZ TALAR THE STRUCTURE AND MAGNETIC PROPERTIES OF BULK AMORPHOUS FECOYB ALLOYS In this paper the results of the structure and magnetic studies for bulk amorphous Fe62Co10Y8B20 and Fe64Co10Y6B20 alloys were presented. For the structural investigation was performed by X-ray diffractometry. It was found that investigated samples were amorphous in the as-cast state. Using a vibrating sample magnetometer (VSM) the magnetisation within magnetic fields ranging from 0 to 2T was measured. On the basis of these investigations the saturation magnetization value and the coercive field were determined. Basing on initial magnetization curve analysis in the area of so-called approach to ferromagnetic saturation, the type of structural defects having influence on magnetization in high magnetic fields were determined.