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IntroductionModern Re-Fe-B hard magnetic materials, produced using rapid quenching technique, taking into account variations in chemical composition, can be divided into three groups i.e. of stoichiometric, Re 2 Fe 14 B composition, and with excess of rare earth or iron [1][2][3].Materials, composed of Re-Fe-B compound with overstoichiometric rare earths, typically are characterized by worse glass transition ability, smallest M r /M s ratio and large coercivity. Their properties are shaped by exchange interactions between Re 2 Fe 14 B, which are weakened by an increased distance between the grains. Enlarged distance between grains is resulting from the presence of a thin boundary formed from an amorphous matrix of redundant rare earths. Additionally, the presence of such a boundary causes an increase in coercivity due to the strong bonding of domain walls at the grain boundaries [4]. The stoichiometric composition causes increase in glass transition ability, M r /M s ratio but also causes deterioration of coercivity. These changes are a result of a reduction in the distance between grains, by removing the paramagnetic amorphous matrix, and fi ner structure as a result of increase in glass transition ability [5]. The highest glass transition ability, fi ner structure and highest M r /M s ratio is met in Re-Fe-B compound with overstoichiometric iron. The signifi cantly higher value of the M r /M s ratio results from the presence of the strong exchange interactions, between particles that differ in magnetic hardness. The grains, of soft magnetic phase, have ribbons obtained by melt-spinning technique. The samples were produced using the rapid cooling of liquid alloy on the copper wheel, by applying three different linear velocities 20, 30, and 35 m/s. The microstructure of obtained ribbons was examined using X-ray diffractometry and Mössbauer spectroscopy. Magnetic measurements were performed using LakeShore vibrating sample magnetometer. The microstructure measurements were used for quantitative and qualitative analysis of phase composition. Basing on results of structure studies combined with magnetic measurements, the infl uence of phase composition on hysteresis loop behavior was described.

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