“…Previous works have noted that X-ray diffraction is unable to reveal the initial low density of Fe a and Fe 3 B clusters in the samples prior annealing but there is experimental evidence of their presence [6,11]. Nevertheless, their diffraction peaks are revealed as the crystals grow and their density increases due to the annealing [11,12]. A depth profile study of the recrystallization of Fe 80 B 20 metallic glass performed with transmission electron microscopy [12] supports this assumption, where similar differences in the recrystallization of the two sides of a Fe 80 B 20 ribbon produced with a single spinning cooling roll were observed and attributed to different quenching rates.…”