Properties of magnetically semi-hard (FexCo1−x)3B compounds

The (FexCo1−x)3B (x = 0.0, 0.1, 0.2, 0.3) compounds have been prepared by induction melting with subsequent annealing. All of the compounds form in the orthorhombic Fe3C-type structure and exhibit ferromagnetic behaviour: the Curie temperature increases from 750 K for x = 0.0 to 923 K for x = 0.3. Magnetic domain images obtained by Kerr microscopy reveal the presence of uniaxial magnetocrystalline anisotropy. The magnetocrystalline anisotropy energy and anisotropy field of magnetically oriented fine particles have been determined. An anisotropy energy of 651 kJm−3 was obtained for Co3B (x = 0.0), the anisotropy energy was found to decrease with increasing Fe content reaching a value of 507 kJm−3 for x = 0.3. These compounds with uniaxial magnetocrystalline anisotropy are potential candidates to be used as semi-hard magnetic phase for the preparation of rare-earth free nanocomposite permanent magnets.