High performance misch-metal (MM)-Fe-B magnets prepared by melt spinning

A series of misch-metal (MM = 28.27 wt % La, 50.46 wt % Ce, 5.22 wt % Pr, 15.66 wt % Nd)-iron-boron isotropic ribbons with atomic formula (MM)_12+xFe_82-x-yB_6+y(x = 0, 1, 2, 3, 4, y = 0, 0.5, 1, 1.5, 2) are prepared by melt spinning technique. A large energy product (BH)_maxof 12 MGOe is obtained with the composition of MM₁₃Fe₈₁B₆at optimized processing. The ribbons with both coercivity larger than 10 kOe and (BH)_maxlarger than 10 MGOe are achieved in a wide composition range. All the samples exhibit the tetragonal crystal structure. The magnetization and Henkel plot (δM) measurements indicate that the ribbons have a relatively homogeneous microstructure and strong exchange-coupling interactions. The average grain size of the ribbons is around 30 nm determined via Scherrer's formula. Meanwhile, the transmission electron microscope (TEM) image also verifies that the ribbons have a homogeneous nanoscale microstructure. In addition, the spin reorientation temperature T_sris investigated by ac susceptibility χ_acmeasurement.