Mössbauer investigations of amorphous Fe[80-x]B20Nbx (x=0,4,6,10) alloys

Purpose: The paper presents a structural and magnetic characterization of selected Fe-based metallic glasses in as-cast state. Design/methodology/approach: The studies were performed on Fe(80-x)B20Nbx metallic glasses in form of ribbons with Nb addition of 0, 4, 6, 10 at.%. The amorphous structure of tested samples was examined by X-ray diffraction (XRD) and Mossbauer spectroscopy methods. The Mossbauer spectroscopy was also applied to comparison of structure in studied amorphous samples with different chemical composition. The thermal properties associated with solidus temperature of master alloys were measured using the differential thermal analysis (DTA). The soft magnetic properties examination of tested materials contained relative magnetic permeability. Finding: The XRD and Mossbauer spectroscopy investigations revealed that the studied alloys in as-cast state were amorphous. The solidus temperature assumed as the onset temperature of the melting peak on the DTA curve reached a value of 1405, 1394, 1392 and 1389 K for Fe80B20, Fe76B20Nb4, Fe74B20, Nb6, and Fe70B20, Nb10 alloy, adequately. The Mossbauer spectra presented broadened six line patterns characteristic to the structural disorder of amorphous ferromagnetic materials. The changing of the average hyperfine magnetic field with niobium addition is connected with structural changing. A high concentration of Nb atoms with high atomic radius can acting as diffusion barrier what lead to formation of regions rich in iron or boron atoms. The niobium addition in Fe[80-x]B20Nbx alloy improves soft magnetic properties in as-cast state. Practical implications: The Mössbauer spectroscopy is very useful method in studying the structural environment of Fe atoms on a nearest-neighbor length scale allowing the analysis of iron-containing phases. Originality/value: The obtained examination results confirm the utility of investigation methods in analysis of microstructure of ferromagnetic glassy alloys.