Synthesis of Fe₉₀Nb₁₀ via wet mechanical milling method and its structural, magnetic and thermal characterization

This study involves the synthesis of nanocrystalline Fe₉₀Nb₁₀ (wt%) binary powders through the use of a high-energy planetary ball mill within an inert argon environment. The milling process was used to investigate changes in structure, morphology and magnetic properties. This was accomplished through the utilization of techniques such as X-ray diffraction (XRD) using the MAUD program, which is based on the Rietveld method, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and vibrating sample magnetometry. From the XRD analysis, it was observed that a disordered solid solution of αFe(Nb) with a body-centred cubic (bcc) crystal structure formed after 12 h of milling. Interestingly, the analysis also indicated that the average crystallite size 〈D〉 within this αFe(Nb) solid solution was remarkably small, measuring a mere 13.15 nm. Furthermore, the ultimate lattice strain 〈σ²〉^1/2 was quantified at 1.08%. It is worth noting that the lattice parameter underwent a rapid and substantial increase, peaking at 0.2879 nm after 36 h of milling. The SEM analyses revealed the development of diverse morphologies at different milling stages. The elemental maps of Fe and Nb done with EDX experiments confirmed the results found by XRD about the evolution of the alloy formation. The changes in saturation magnetization (M_s), coercive field (H_c), remanent magnetization (M_r) and squareness ratio (M_r/M_s) were investigated in relation to microstructural modifications during the milling process. Annealing Fe₉₀Nb₁₀ (wt%) samples promotes the formation of a homogeneous solid solution and increases coercivity.