Effects of Yttrium and Cerium co-substitution on Structures and Magnetic Properties of Nanocrystalline Nd-Fe-B Magnets

Abstract

Cerium-containing (Ce) rare earth magnets with extraordinary cost-effectiveness are widely investigated around the world. However, when the concentration of Ce is much more, the kind of these magnets exhibits very poor thermal stability and overall magnetic properties. To weaken these disadvantages, we take eutectic Y 50 Ce 50 co-substitution alloys into account in this work. Magnetic properties, microstructures and metallurgical behaviors of (Y, Ce, Nd)-Fe-B magnets are systematically researched. For (Y 50 Ce 50 ) 10 Nd 20 Fe 68.9 B 1.1 SPSed permanent magnets, good overall magnetic properties are H cj = 725 kA/m, J r = 0.73 T and ( BH ) max = 81 kJ/m 3 . It schematically depicts that coarse grain zones and fine grain zones occur during the spark plasma sintering (SPS) process. With the Nd content increasing, the deleterious CeFe 2 phases disappear. In addition, the volume fraction and width of coarse grain zones decrease. Ce-rich and Ce-lean regions are also observed in main phases, while Y and Nd elements are uniformly distributed. TEM results show that Nd and Ce are rich in the grain boundary and Y elements prefer to enter in 2:14:1 main phases. This work is favorable to a balanced utilization of high abundance rare earth elements in Nd-Fe-B magnets.