Microstructure refinement and magnetic properties enhancement for nanocomposite RE2Fe14B alloys by Zr additions

The effects of Zr-substitution on the microstructure and magnetic properties of [(PrNd)0.32La0.22Ce0.46]22.0Fe76.7−xZrxB1.3 (x = 0, 2.5, 5, 7.5 wt%) melt-spun powders have been investigated. It is shown that the Zr addition can prevent the formation of CeFe2 phase and α-Fe phase, increasing the volume fraction of 2:14:1 phase. Furthermore, the Zr addition can refine the grain sizes of α-Fe and 2:14:1 phases. Meanwhile, the formation of Fe2Zr phase and the decrease of CeFe2 phase improve its antioxidation. And the magnetic properties of bonded magnets are found to increase significantly. The coercivity Hcj increases from 2.57 kOe for the Zr-free sample to 5.86 kOe for the Zr-doped sample. The maximum energy product (BH)max of bonded magnets increases from 3.13 MGOe to 6.19 MGOe correspondingly, which attribute to the fine microstructure.