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chemically inhomogeneous re-fe-b permanent magnets with high figure of merit: solution to global rare earth criticality

by:Newland     2019-08-29
Global rare earth (RE)
The key, especially those
Dependent on Nd/Pr/Dy/Tb in 2: 14: 1-
Permanent magnet for typing (PMs)
Has triggered a huge attempt to develop new alternatives.
However, La/Ce, a potential candidate with high abundance, due (La/Ce)
2Fe14B to Nd2Fe14B.
Here we report high numbers. of-merit La/Ce-rich RE-Fe-
B PMs, where the distribution of La/Ce is uneven at 2: 14:1 stage.
The exchange coupling generated inside a single particle and the static magnetic interaction between the particles ensure superior performance than the La/Ce uniformly distributed magnet.
Maximum energy products (BH)max of 42.
2 MGOe can be implemented even with 36 wt. % La-
Ce company.
Cost performance ,(BH)
The highest/cost has increased by 27.
1% compared to 48. 9 MGOe La/Ce-
Free commercial magnet.
The construction of chemical heterogeneity provides recipes for commercial development
Grading PMs using a less risky La/Ce and providing a promising solution for REs availability restrictions.
The nominal composition is (Pr, Nd)GdFeB (I: La/Ce-free terminal)and (Pr, Nd)(La, Ce)GdFeB (II: La/Ce-
Rich terminal, 30 tons. % La-
Ce concentration of TRE)(
= Cuccu, Al, Nb, Zr in Wt. %)
Preparation by induction melting, casting tape, hydrogen explosion and jet milling.
Raw material Pr-
The Nd alloy represents 20 wt. % Pr-80u2009wt.
% Nd composition, La-
Ce alloy is made of 35wt wt. % La and 65u2009wt. % Ce.
By adjusting the mass ratio of the two types of powder (see )
, 9, 12, 15, 18 weight magnets. % La-Ce (La-
Ce content of TRE)
Preparation by traditional powder metallurgy process.
5 after pressing.
5mpa mpa in vertical magnetic field 1.
The green contract of 200 MPa 5 kg/t and equilibrium reduction is sintering 1000 ~ 1075 ° C after annealing ~ 870 ° C ~ 900 °C and 460 °C ~ 620 °C.
At the same time, start the magnet (
Use only La/Ce-free terminal)and magnets (
3, 6, 9 rwWt by direct alloy. % La-
Ce to component I)
It was prepared under the same conditions. XRD patterns (
10 ° ≤ 2 ° ≤ 100 °, the step size is 0.
02 ° and counting time for each step of 4S using Shimadzu X-ray diffraction6000)
Refined with Rietveld (
Rietica software)
Confirm La/Ce-free and La/Ce-
The rich terminals and magnets have similar phase components, from the matrix REFeB phase and a small amount of RE-rich phase (
Figure S6 and S7).
According to the calculation of this average measurement, it can be seen well that the higher La-
Ce content, smaller lattice parameters and 2: 14:1 phase.
Element concentration mapping using an electronic probe micro-analyzer (EPMA)
X-with wavelength dispersion-
Ray Spectrometer (WDS).
Measurement of magnetic properties by AMT4 magnetometer.
The Curie point temperature is determined by measuring the Thermal magnetic curve, which is heated to 400oe ℃ at 2 °c/min and the field is 200oe oe.
The initial magnetized curve and recoil loop are characterized by a vibrating sample magnetic meter (VSM)up to 5u2009T.
The thermal stability of residual magnetism is investigated ()
And magnetic strength ()(
From 20 to 100 °C)
, And irreparable losses-circuit flux (
From 20 °c to 15 °c).
Microstructure and electron diffraction were characterized by transmission electron microscopy (JEM-2100F)
Equipped with EDS.
The magnetic domain structure was observed by Lorenzo TEM (Fresnel method)
Digital enhanced Kerr microscope.
Through standard mechanical grinding, depression (Gatan 656)
Ion milling (Gatan 691). Ion-
On both sides of the sample, the beam is refined at an angle of inclination of 8 ° between the beam and the surface of the sample.
Samples of Kerr
Image observations are prepared by standard grinding and polishing.
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