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

Abstract

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 (La1−xYx)2Fe14B 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 Tc increases linearly. Y substitution also can effectively enhance the inter-grain exchange coupling and the corrosion resistance of La2Fe14B alloy. The corrosion current density icorr decreases from 36.2 μA/cm2 to 10.6 μA/cm2 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 Nd2Fe14B alloy. The hard magnetic properties with maximum energy product (BH)max of 2.6 MGOe, remanent polarization Jr of 0.65 T, and intrinsic coercivity Hcj of 84 kA/m have been obtained in (La0.7Y0.3)2Fe14B alloys. Y2Fe14B alloy shows the highest (BH)max of 6.8 MGOe, Jr of 0.88 T, and Hcj 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.