X-Ray Diffraction and Mössbauer Studies of Nanostructured Ni₄₀Fe₆₀ Powder: Structure Defects and Hyperfine Structure

A nanostructured nickel–iron alloy having the Ni₄₀Fe₆₀ composition was prepared through the mechanical alloying of the elemental powders in a high-energy ball mill P7 under an argon atmosphere. The microstructural, structure defects, and hyperfine properties during mechanical alloying were characterized by X-ray diffraction, scanning electron microscopy, and Mössbauer spectroscopy. The analysis of XRD spectra shows that the final product obtained was a nanostructured fcc-Ni(Fe)-rich phase. Whereas a more precise analysis by Mössbauer spectroscopy indicates that, in addition to paramagnetic phase rich with Ni, disordered ferromagnetic solid solutions fcc-Ni(Fe) and bcc-Fe(Ni) are present. The resulting nanostructure is demonstrated in accordance with the concept of dislocations; the dislocation densities were found to be around 5 × 10¹⁶ m⁻² after 50 h milling.