Nd5Fe64B23Mo4Y4 bulk nanocomposite permanent magnets produced by crystallizing amorphous precursors

Abstract The glass forming ability and magnetic properties of Nd 5 Fe 68 − x B 23 Mo 4 Y 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 5 Fe 64 B 23 Mo 4 Y 4 alloy. After annealing for 10 min at 1013 K, the Nd 5 Fe 64 B 23 Mo 4 Y 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 3 B (30–35 nm) and hard Nd 2 Fe 14 B (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.