Mössbauer study of the crystallization of Fe100−xBx amorphous alloys (14≤x≤25)

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Abstract
The crystallization of Fe100−xBx amorphous alloys (x=14, 20, and 25), prepared by rapid quenching from the melt, was studied by Mössbauer effect spectroscopy. In general, the present results support recent nuclear magnetic resonance studies (performed on the same samples used in this work), which indicated that the amorphous material had a body‐centered‐tetragonal Fe3B‐like short‐range order for x=25 but an orthorhombic Fe3B‐like one for x=14. For x=25, annealing at about 400 °C led to the formation of almost pure body‐centered‐tetragonal Fe3B. On the other hand, thermal treatments at about 800 °C produced a mixture of phases for all the compositions. For x=14, formation of body‐centered‐tetragonal Fe3B was not observed in any case. In addition, the present Mössbauer results, combined with the previous nuclear magnetic resonance ones, show that boron and iron atomic surroundings evolve differently when alloys with x=14 are annealed at 390–420 °C. In the boride phase, the 57Fe Mössbauer signal remained ‘‘amorphouslike’’ in contrast with the 11B nuclear magnetic resonance signals which became sharp and corresponded to those in tetragonal and orthorhombic Fe3B and in Fe2B. These results would indicate that under these experimental conditions the surroundings of the boron atoms become ordered before the surroundings of the iron atoms.