Magnetic properties and microstructure of bulk Nd-Fe-B magnets solidified in magnetic field

摘要

The Nd-Fe-B bulk magnets with a slab shape of 0.9 x 4 x 15 mm3 were prepared by injection casting into a copper mold. The effects of applying a magnetic field during the casting process on the magnetic properties and microstructure of Nd_(9.5)Fe_(71.5)Ti_(2.5)Zr_(0.5)Cr_1B_(14.5)C_(0.5) alloy have been studied. The results show that the sample cast with magnetic field has a stronger (00L) texture of Nd_2Fe_(14)B phase with the c-axis perpendicular to the slab plane than the sample cast without magnetic field. The intensity of the texture weakens from surface to inner region of the bulk magnets. Applying a magnetic field during the casting process is helpful to refine the grain size effectively. As a result, the magnetic properties are improved from B_r = 5.8 kG, _iH_c = 6.5 kOe, and (BH)_(max) = 5.9 MGOe for the sample cast without magnetic field to B_r = 6.1 kG, _iH_c = 10.3 kOe, and (BH)_(max) = 7.3 MGOe for the sample cast with a 3.7 kOe magnetic field.