Fe ₆₅B ₂₂Nd ₉Mo ₄ bulk nanocomposite permanent magnets produced by crystallizing amorphous precursors

The Fe ₆₅B ₂₂Nd ₉Mo ₄ nanocomposite permanent magnets in the form of a rectangular cross sectioned rod have been prepared by annealing the amorphous precursors. The thermal behavior, structure and magnetic properties of the magnets have been investigated by differential scanning calorimetry, X-ray diffractometry, electron microscopy and magnetometry techniques. The as-cast Fe ₆₅B ₂₂Nd ₉Mo ₄ alloy showed soft magnetic properties, which changed into magnetically hard after annealing. Results provoke that the magnetic properties of the alloy are sensitive to thermal processing conditions. The optimum hard magnetic properties with a remanence (B _r) of 0.56 T, coercivity ( _iH _c) of 920.7 kA/m and maximum energy product (BH) _max of 50.15 kJ/m ³ were achieved after annealing the alloy at 983 K for 10 min. The good magnetic properties of Fe ₆₅B ₂₂Nd ₉Mo ₄ magnets are ascribed to the exchange coupling between the nano-scaled soft α-Fe, Fe ₃B and hard Nd ₂Fe ₁₄B magnetic grains.