In this study, amorphous powders of Fe-Cu-Nb-Si-B composition were synthesized through gas and water
atomization techniques utilizing industrial-grade raw materials. Subsequently, these powders underwent a sieving
process to achieve a particle size classification under 53 μm, with an average particle size (D50) of 26 μm.
The prepared powder underwent a series of heat treatments at temperatures of 450 °C, 475 °C, 500 °C, 525 °C,
and 550 °C to investigate changes in its crystallographic structure, utilizing X-ray diffractometry (XRD). Simultaneously,
magnetic properties were assessed through Mössbauer spectroscopy and vibrating sample magnetometry
(VSM). The observed phase transformation progressed from amorphous to crystalline as the heat
treatment temperature increased. An entirely amorphous phase was maintained up to 500 °C, beyond which a
mixed amorphous and crystalline phase emerged at higher temperatures. Mössbauer analysis revealed that, at
525 °C, approximately 39 % of the material remained in an amorphous state, while 61 % had transitioned into
a crystalline phase. Further, at 550 °C, the amorphous fraction decreased to approximately 31 %, while the
crystalline fraction increased to 69 %. The crystalline phase was identified as consisting of α-Fe, α-FeSi, Fe2Si,
Fe3Si at A-sites, Fe3Si at B-sites, and Fe2B sites in the case of the 550°C heat treatment. With increasing heat
treatment temperature, the saturation magnetization exhibited an initial increase, followed by a decline from
550 °C onward. This decline coincided with the decomposition of the material into multiple crystalline phases.
Moreover, the Curie temperature was determined to be TC1=845 K and TC2=955 K, indicating two distinct
magnetic transition temperatures in the studied material.