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

Highlights: • Zr was added in Nd-Ce-Fe-B magnet to increase the magnetic properties. • The Zr addition can prevent the formation of CeFe₂ phase. • The Zr addition can increasing the volume fraction of 2:14:1 phase. • The magnet with Zr addition has a excellent performance. Hcj = 5.86 kOe. (BH)_m = 6.19 MGOe. The effects of Zr-substitution on the microstructure and magnetic properties of [(PrNd)_0.32La_0.22Ce_0.46]_22.0Fe_76.7−xZr_xB_1.3 (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 H_cj 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.