Enhanced coercivity of spark plasma sintered (La,Ce)FeB magnets

The increasing global demand on Nd-Fe-B makes rare earth (Re) elements including Nd, and Tb facing long-term criticality due to resource limitation and price, it is important to develop new Re-Fe-B magnets with high content of light rare earths (LRe) such as La and Ce which are more abundant and cheaper. However, large amounts exceeds 40 wt.% of La/Ce substitutions for Nd or Pr worse the properties. In addition, the nonmagnetic CeFe₂ phase, which coexists with the main 2:14:1 phase, lowers the intrinsic magnetic properties of La/Ce-FeB. It is reported that the substitution of La for Ce can inhibit the formation of CeFe₂ and improve the magnetic properties of CeFeB magnets. In this study, we prepared a series of (La/Ce)FeB ribbons and investigated the effect of La content on the structure and magnetic properties. Based on the optimized (La/Ce)FeB ribbon, spark plasma sintered (SPS) nanocrystalline bulks with high density were fabricated, and (La/Ce)FeB magnets with NdCu additions, to improve the coercivity, were also investigated.