Magnetic properties and domain structures in Nd–Fe–B sintered magnets with Tb additive reacted and diffused from the sample surface

摘要: Abstract We investigated the magnetic properties and domain structures of Nd–Fe–B sintered magnets with a Tb additive reacted diffused from sample surface. characterized these using vibrating magnetometry, Kerr effect microscopy, electron probe microanalysis. In (R-Tb) in this study, concentration was higher on its surface (∼30 μm depth) interior grain boundaries than inside subsurface crystal grains. The saturation polarization (Js) about 6% lower non-reacted (N-Tb); which should come Js decrease Tb-substituted regions R-Tb sample. substitution greatly improved coercivity (Hc) samples 1.02 MA/m (N-Tb) to 1.72 (R-Tb). To understand reason increase, we measured widths (dD) near-surface region (5–10 μm polished deeper below N-Tb samples. average dD approximately 20% wider other planes, where 1.0 μm for both addition considering reasons enhancement, used novel step method compare demagnetization behaviors likely had enhanced mainly because difficulty nucleating reversal portions. This caused by enlargement anisotropy field (Ha = 2K1/Js) diffusion reaction. ∼20% plane also explained decrease.