Magnetic and crystallization behavior of Be‐substituted Fe82B18 metallic glasses

Substitution of Be for B in the amorphous binary alloy Fe82B18 was observed to cause an initial increase in saturation magnetization (Ms) to a maximum of 200 emu/g at 4.2K, followed by a decrease for alloys with more than 4 at.% Be. Meanwhile, the Curie temperature of the Fe82B18−y Bey alloys decreased progressively with the Be content. These changes in Ms and TC differ from those observed in the Fe‐B‐M′ metallic glasses, where M′ is another metalloid (P, C, Si or Ge). Results from Auger electron spectroscopy and Mossbauer experiments confirmed the reversal trend detected in the magnetization measurements. Combining all these results enables us to attribute the initial increase in Ms to a smaller charge transfer from the Be atoms than that from the B atoms to Fe and the subsequent decrease in Ms to a possible clustering of the Be atoms at higher concentrations. The annealing behavior for the present alloys is described in terms of crystallization stages and the phases formed.