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