Effect of High-Energy Ball Milling on the Structural and Magnetic Behavior of Fe₆₀Al₄₀ Alloy

In the present work, nanocrystalline binary Fe₆₀Al₄₀ (wt.%) powders have been synthesized by a high-energy planetary ball mill under an inert argon atmosphere. The evolution of structural, morphological, and magnetic properties of ball-milled powders was studied as a function of milling time using x-ray diffraction (XRD), scanning electron microscopy with energy-dispersive x-ray spectroscopy (SEM/EDX), transmission electron microscopy (TEM), and a vibrating sample magnetometer (VSM). A disordered α-Fe(Al) solid solution with a body-centered cubic (bcc) crystal structure was formed after 14 h of milling from XRD results. It was found that the average crystallite size (D) of the α-Fe(Al) solid solution was as low as 14 nm, while the final value of the lattice strain (ε) was found to be 1.08%. Furthermore, the lattice parameter rapidly increased to a maximum value of 2.8749 Å after a milling time of 20 h. The SEM results showed that various morphologies were formed during the milling stages. Further, EDX examinations were used to investigate the chemical composition homogeneity and the form of the Fe₆₀Al₄₀ powders. The magnetic properties of milled Fe₆₀Al₄₀ powders, such as saturation magnetization (Ms), remanence (Mr), coercive field (Hc), and remanence to saturation ratio (M_r/M_s), were discussed as a function of milling time. The milled samples exhibited soft-hard ferromagnetic behavior, where the magnetic parameters are shown to be extremely sensitive to the milling time. This is mainly due to the particle size refinement as well as the formation of the α-Fe(Al) solid solution.