Influence of Magnetic Field on Dealloying of Al-15Fe Ribbons and Formation of Fe3O4 Octahedra

The dealloying behavior of Al-15Fe (at.%) ribbons in a 5 mol·L_-1 NaOH solution under static magnetic field has been investigated. The as-dealloyed samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis. The results reveal that Al atoms can be leached out from the a-Al(Fe) and Al₁₃Fe₄ phases in NaOH solutions with magnetic field, and the magnetic field can significantly reduce the particle size of the as-dealloyed samples comparing with those from non-treatment dealloying (1093 ± 202 nm). The average edge lengths of these octahedra are 303 ± 67 nm (under 0.25 T), 380 ± 141 nm (0.5 T), 421 ± 187 nm (0.75 T), respectively, implying that an optimized selection of magnetic intensity is helpful to obtain refined Fe₃O₄ particles. In addition, the particle morphology is obviously influenced by magnetic field and the effects were also systematically discussed.