Understanding the phase structure, magnetic properties and anti-corrosion behavior of melt-spun (La,Y)2Fe14B alloys

Abstract Aiming to develop the rare earth-iron-boron permanent magnets with high performance/cost ratio, a systematic investigation on the phase structure, microstructure, magnetic properties, and corrosion resistance of melt-spun nanocrystalline (La 1−x Y x ) 2 Fe 14 B alloys has been carried out. In La based alloys, at least 20 at% Y substitution for La is needed to form hard magnetic 2:14:1 phase. With the increase of Y content, the lattice parameters a , c of 2:14:1 phase decrease and its Curie temperature T c increases linearly. Y substitution also can effectively enhance the inter-grain exchange coupling and the corrosion resistance of La 2 Fe 14 B alloy. The corrosion current density i corr decreases from 36.2 μA/cm 2 to 10.6 μA/cm 2 in 3.5 wt% NaCl solution with increasing x from 0.2 to 1.0, and all these values are lower than those for nanocrystalline Nd 2 Fe 14 B alloy. The hard magnetic properties with maximum energy product (BH) max of 2.6 MGOe, remanent polarization J r of 0.65 T, and intrinsic coercivity H cj of 84 kA/m have been obtained in (La 0.7 Y 0.3 ) 2 Fe 14 B alloys. Y 2 Fe 14 B alloy shows the highest (BH) max of 6.8 MGOe, J r of 0.88 T, and H cj of 148 kA/m. This work suggests that La-Y-Fe-B alloys also have the potential for fabricating new and low-cost magnetic materials with performance better than hard ferrites.