Thermally Induced Structural Transformations of Fe₄₀Ni₄₀P₁₄B₆ Amorphous Alloy

Thermal stability and thermally induced structural transformations of Fe₄₀Ni₄₀P₁₄B₆ amorphous alloy were examined under non-isothermal and isothermal conditions. Formation of metastable α-(Fe,Ni), and stable γ-(Fe,Ni) and (Fe,Ni)₃(P,B) crystalline phases as the main crystallization products was observed, while the presence of small amounts of other crystalline phases like Fe₂₃B₆ and Fe₂NiB was indicated by electron diffraction in HRTEM. Thermomagnetic curve indicated that Fe content in different crystalline phases is very different, resulting in markedly different Curie temperatures after crystallization. Transmission electron microscopy and atomic force microscopy study suggested multiple-layered platelet-shaped morphology, both on the surface and in the bulk of the crystallized alloy sample. The thermal treatment heating rate and maximum temperature affected surface roughness and grain size inhomogeneity.