Sintered Nd-Fe-B magnets are widely used in various applications such as motors, generators, and sensors, due to their high magnetic energy product and coercivity. However, the increasing demand and price of rare earth elements (REEs), especially Nd and Dy, have posed challenges for the sustainable development of Nd-Fe-B magnets. Therefore, researchers have explored the possibility of using Ce, a low-cost and abundant REE, to partially or fully replace Nd in Nd-Fe-B magnets.
Ce-containing sintered Nd-Fe-B magnets have several advantages over conventional Nd-Fe-B magnets. First, they can reduce the cost and improve the resource utilization of REEs. Second, they can achieve tunable magnetic properties by adjusting the Ce content and the microstructure. Third, they can enhance the temperature stability and corrosion resistance of Nd-Fe-B magnets by introducing Ce-rich phases.
However, Ce-containing sintered Nd-Fe-B magnets also face some challenges. One of them is the lower intrinsic magnetic properties of Ce2Fe14B compared to Nd2Fe14B. Another one is the formation of CeFe2 phase, which has a high melting point and hinders the diffusion of other elements. Therefore, various methods have been proposed to improve the performance of Ce-containing sintered Nd-Fe-B magnets, such as grain boundary diffusion, dual-main phase, and hot deformation.
The following table summarizes the magnetic properties and microstructures of some Ce-containing sintered Nd-Fe-B magnets reported in the literature.
| Ce content (wt%) | (BH)max (kJ/m3) | Hcj (kA/m) | Microstructure | Reference |
|---|---|---|---|---|
| 0 | 398.4 | 1124.7 | Nd2Fe14B | 1 |
| 5 | 358.4 | 1656.4 | Nd2Fe14B + Ce-rich phase | 1 |
| 31.8 | 247.2 | 1179.7 | Ce2Fe14B + Ce-rich phase | 2 |
| 100 | 160 | 800 | Ce2Fe14B + Ce-rich phase | 3 |
