Magnetic Properties and Magnetic Domain Observation of Nd–Fe–B Sintered Magnets Treated by Grain Boundary Diffusion Process with Dy–Al Co-Sorption

Effective grain boundary diffusion (GBD) process with Dy–Al co-sorption is applied to enhance the coercivity of Nd–Fe–B sintered magnets. The magnet (HcJ = 1789 kA·m?1) subjected present GBD treatment was observed be superior that untreated 1003 and conventional 1661 treated DyAl alloy. In magnet, facilitated Dy into center region (thickness: 3.5 mm), resulting in high coercivity. Further, magnetic domain observations were made using force microscopy (MFM) observe thermal demagnetization behavior magnet. suppressed continuous reversal adjacent grains; thus, partially persistent single-domain structure remained, even at 453 K.