Enhancing coercivity and thermal stability of (Nd,Y)–Fe–B sintered magnets through lamellar structure design

Abstract

The incorporation of the high-abundance rare-earth element Y in (Nd,Y)–Fe–B sintered magnets offers an opportunity to reduce the cost of permanent magnetic materials, while promoting the balanced usage of rare-earth resources. However, the performance of (Nd,Y)–Fe–B magnets prepared using the conventional dual-main-phase (DMP) method undergoes significant degradation due to the strong diffusion ability of Y. To suppress the excessive diffusion of Y, this study presents a macroscopic lamellar magnet preparation scheme. Consequently, the micromagnetic simulations revealed that the multilayer magnets exhibited superior intrinsic performance compared to DMP magnets. Subsequently, the multilayer magnets were prepared by alternately stacking the 0% Y (0Y) and 30% Y (30Y) magnetic powders. The observed magnetic properties demonstrated that the coercivity of the three-layer magnet was ~ 0.23 T higher than that of the DMP magnet, leading to improved coercivity stability at high temperatures. Furthermore, the microstructural observations and elemental analyses indicated the presence of a ~ 200-μm-thick interface layer at the contact site between the 0Y and 30Y magnetic layers. Thus, the proposed approach effectively suppressed the excessive diffusion of Y in (Nd,Y)–Fe–B magnets, thereby enhancing the magnetic performance of the sintered magnets.

Graphical Abstract