High performance Nd-Fe-B permanent magnets without critical elements

Abstract

Scanning electron microscopy, and magnetization measurements reveal that as cast (Nd 1-x Ce x ) 2 Fe 14 B alloys contain significant amounts of -Fe that can be dramatically reduced by annealing the alloys at 1000 o C for 3 days. The room temperature intrinsic coercivity, Hci, of (Nd 0.8 Ce 0.2 ) 2.2 Fe 14 B melt spun ribbons was found to be 11 kOe, which is 32 to 10% higher in comparison to that of Nd 2 Fe 14 B (Hci = 8.3 kOe), and (Nd 0.8 Ce 0.2 ) 2.0 Fe 14 B (Hci = 10 kOe), respectively. The substitution of Co for Fe in (Nd 0.8 Ce 0.2 ) 2 Fe 14-z Co z B significantly increases both T C and the maximum energy product, (BH)max. Our study shows that both Co-containing and Co-free Ce-substituted Nd 2 Fe 14 B alloys have excellent magnetic properties at room temperature and above. The experimental results also demonstrate the potential of Nd-Ce-Fe-TM-B based alloys as alternative to expensive Dy-containing high performance rare earth magnets. a corresponding author: pathak138@ameslab.gov

Rare Earths and the Balance Problem: How to Deal with Changing Markets?

“…A very active field of research is the development of Nd-Fe-B magnets, in which part of the neodymium is replaced by cerium or by mischmetal (i.e., La ? Ce mixture) [65,66]. Up to 20 wt% of neodymium can be replaced without compromising too much on the magnetic properties.…”

Single-Crystal Permanent Magnets: Extraordinary Magnetic Behavior in theTa-,Cu-, andFe-SubstitutedLamichhane1, Onyszczak2, Palasyuk3 et al. 2019Phys. Rev. AppliedSelf Cite

“…7 (f) is a high resolution STEM image taken from the matrix in Fig. 7 (d) under [1][2][3][4][5][6][7][8][9][10] zone axis. It is the same as that seen in Fig.…”

“…Despite the mixed Ce 3+ /Ce 4+ valency problem, typically adverse for the magneto-crystalline anisotropy, there are recent experimental efforts on the Nd 2 Fe 14 B (2:14:1) system showing that Ce-substitutes can compete with commercial high-flux grades at lower material costs. [4][5][6][7] Similarly, efforts on the Ce-containing SmCo 5 (1:5) and Sm 2 Co 17 (2:17) systems showed that satisfactory cost-toperformance balances suitable for modern rare earth criticalities and market demands are expected. [8][9][10][11] Therefore, we believe that Cu and Fe substituted CeCo 5 systems require a new and deeper examination.…”

Understanding the element segregation and phase separation in the Ce-substituted Nd-(Fe,Co)-B based alloys

“…Even though the intrinsic properties of the Ce 2 Fe 14 B phase ( J s  = 1.17 T, H a  = 30 kOe and T c  = 442 K) are relatively lower compared to those of Nd 2 Fe 14 B (2:14:1) phases 3 . Some experimental studies suggested that up to 30 at.% substitution of Ce for Nd in Nd-Fe-B alloys did not destroy the magnetic properties, but further increase of Ce content would reduce the hard magnetic properties significantly 4,5 . Particularly, several topics deserve more attention in the case of Ce-substituted Nd-Fe-B magnets.…”