Nd ₅Fe ₆₄B ₂₃Mo ₄Y ₄ bulk nanocomposite permanent magnets produced by crystallizing amorphous precursors

The glass forming ability and magnetic properties of Nd ₅Fe _{68 - x}B ₂₃Mo ₄Y _x (x = 0, 2, 4, 6) alloys prepared by copper mold casting technique have been studied. Amorphous rods with a diameter of 2 mm were obtained in the Nd ₅Fe ₆₄B ₂₃Mo ₄Y ₄ alloy. After annealing for 10 min at 1013 K, the Nd ₅Fe ₆₄B ₂₃Mo ₄Y ₄ alloy showed optimal hard magnetic properties with the coercivity of 764.2 kA/m, remanence of 0.6 T and maximum energy product of 57.3 kJ/m ³, respectively. The enhanced magnetic properties can be ascribed to the strong exchange coupling among the magnetically soft α-Fe (25-30 nm), Fe ₃B (30-35 nm) and hard Nd ₂Fe ₁₄B (40-50 nm) grains present in the magnet microstructure. Large size bulk nanocomposite magnets with sound magnetic properties make the Nd-Fe-B-Mo-Y alloy system a promising candidate for industrial applications.