[en] Ultrafine Fe-B amorphous alloy powders were prepared by reducing Fe²⁺ ions using KBH₄ and NaBH₄ in aqueous solution. Adjusting technological factors, the amorphous powders around the composition of Fe₆₅B₃₅ can be easily obtained, but in the vicinity of eutectic point (Fe₈₀B₂₀) a certain amount of α-Fe often appears in the samples. From the Moessbauer spectrum, the crystallization products of the Fe₆₃B₃₇ amorphous powder are α-Fe and Fe₂B phases. The measurement of ¹¹B spin echo nuclear magnetic resonance (NMR) at 8 K showed that Fe₂B-like and Fe₃B-like short range orders (SRO) exist in the amorphous powder of Fe₇₆B₂₄. (orig.)