Effects of lanthanum substitution on microstructures and intrinsic magnetic properties of Nd-Fe-B alloy

(Nd1–x La x)30Fe69B(x=0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) alloys were prepared by inducting melting, and the effect of substitution of La for Nd on their microstructure and intrinsic magnetic properties were investigated. With the increase of La content, Curie temperature(T c) decreased from 582.4 to 557.4 K, saturation magnetization(M s) decreased from 1.59 to 1.37 T, and anisotropy field(H A) decreased from 5394 to 3911 k A/m. However, the reductions of the intrinsic magnetic properties were relatively gentle as La content increased, which meant that the intrinsic magnetic properties still had the potential to fabricate permanent magnets. Moreover, further microstructure observations showed that La tended to diffuse into the Nd-rich grain boundary phase instead of main phase during the substitute process. Such aggregation behavior was beneficial to fabricating La containing magnet with high M s.