Grain boundary phases in (Ga, Cu)-doped Nd-Fe-B sintered magnet
Source abstract
Abstract
The nano-scale non-ferromagnetic thin grain boundary (GB) phase plays an important role in enhancing coercivity of Nd-Fe-B magnets. However, it is a great challenge to simultaneously explore the structure, composition and magnetism of thin GB phases due to their ultrafine scale. Here, aside from common Nd 6Fe 13Ga, NdO and Nd 5Ga 3 phases, a kind of thin GB phase with excellent wettability has been found in the (Ga, Cu)-doped Nd-Fe-B sintered magnet, which is analyzed to be a new Nd-rich phase with the composition of Nd 49.6Pr 18.5Fe 6.8Co 6.7Cu 15.1Ga 3.3 (at.%). Using tilt-series electron diffraction, it is determined to be tetragonal with lattice parameters a = 13.2 Å and c = 5.4 Å. Lorentz microscopy further reveals that the new Nd-rich phase is non-ferromagnetic and its existence at thin GBs as thin as about 10 nm is beneficial for magnetically isolating adjacent grains and improving coercivity. Besides, a new Fe-rich phase with the composition of Nd 32.1Pr 8.5Fe 48.4Co 3.3Cu 1.9Ga 3.5Al 2.3 (at.%) has also been found in the magnet, which is needle-shaped and located at triple junctions. Tilt-series electron diffraction has determined it to be hexagonal with lattice parameters a = 17.6 Å and c = 29.2 Å.
Source: expertdata · Quality: candidate unverified · Source record ↗
Research context
OpenAlex topics: Magnetic Properties of Alloys · Magnetic properties of thin films · Magnetic and transport properties of perovskites and related materials
SciVX discovery tags are terminology-based. OpenAlex topics are source-provided classifications.
References (65)
Show source-provided references
1. Chapter 4 - Advances in Nd-Fe-B based permanent magnets10.1016/bs.hmm.2018.08.003 ↗
2. Magnetic materials and devices for the 21st century: stronger, lighter, and more energy efficient10.1002/adma.201002180 ↗
3. Prospect for HRE-free high coercivity Nd-Fe-B permanent magnets10.1016/j.scriptamat.2018.03.012 ↗
4. Most frequently asked questions about the coercivity of Nd-Fe-B permanent magnets10.1080/14686996.2021.1916377 ↗
5. Permanent magnet materials based on the rare earth-iron-boron tetragonal compounds10.1109/TMAG.1984.1063214 ↗
6. Strategy for high-coercivity Nd–Fe–B magnets10.1016/j.scriptamat.2012.06.038 ↗
7. Formation of non-ferromagnetic grain boundary phase in a Ga-doped Nd-rich Nd–Fe–B sintered magnet10.1016/j.scriptamat.2015.10.042 ↗
8. Magnetic properties evolution with grain boundary phase transformation and their growth in Nd-Fe-Cu-Ga-B sintered magnet during post-sinter annealing process10.1016/j.intermet.2021.107303 ↗
9. Relationship between the microstructure, local magnetism and coercivity in Ga-containing Nd-Fe-B sintered magnets10.1016/j.actamat.2020.116517 ↗
10. Correlative multi-scale characterization of a fine grained Nd-Fe-B sintered magnet10.1016/j.ultramic.2013.01.006 ↗
11. Dependence of the crystal structure of the Nd-rich phase on oxygen content in an Nd–Fe–B sintered magnet10.1016/j.scriptamat.2008.03.004 ↗
12. Effect of carbon on the coercivity and microstructure in fine-grained Nd–Fe–B sintered magnet10.1016/j.actamat.2014.10.047 ↗
13. Effect of post-sinter annealing on the coercivity and microstructure of Nd–Fe–B permanent magnets10.1016/j.actamat.2008.11.019 ↗
14. Grain boundary and interface chemistry of an Nd–Fe–B-based sintered magnet10.1016/j.actamat.2011.10.043 ↗
15. Influence of Nd/Nd2Fe14B interface microstructure on the coercivity of surface Nd2Fe14B grains in Nd-sputtered Nd–Fe–B sintered magnets10.1016/j.scriptamat.2008.03.003 ↗
16. Microstructure of a Dy-free Nd-Fe-B sintered magnet with 2 T coercivity10.1016/j.actamat.2018.06.037 ↗
17. Structure and chemical compositions of the grain boundary phase in Nd-Fe-B sintered magnets10.1016/j.actamat.2016.05.035 ↗
18. Transmission electron microscopy study on Nd-rich phase and grain boundary structure of Nd-Fe-B sintered magnets10.1063/1.1851017 ↗
19. Temperature dependence of the crystal structures and phase fractions of secondary phases in a Nd-Fe-B sintered magnet10.1016/j.actamat.2018.05.020 ↗
20. Electron microscopy of Nd-Fe-B based magnets10.1016/0304-8853(89)90323-5 ↗
21. Microstructure of Fe-didymium-B magnets
22. On the phase NdFe4B4 and its implication in the magnetic hardening of Nd2Fe14B permanent magnets10.1016/0022-5088(84)90426-0 ↗
23. Some new Nd-rich carbides formed by solid state reaction of and carbon10.1088/0022-3727/31/5/004 ↗
24. Effects of grain boundary phase on coercivity of dysprosium-free rare earth magnet10.2320/matertrans.M2016160 ↗
25. Role of Ga on the high coercivity of Nd-rich Ga-doped Nd-Fe-B sintered magnet10.1016/j.jallcom.2019.03.114 ↗
26. Significant coercivity enhancement of Ga-doped sintered Nd-Fe-B magnet by grain boundary diffusion perpendicular to the c-axis10.1016/j.jmmm.2023.170963 ↗
27. Preparation and TEM-study of sintered Nd18Fe74B6Ga1Nb1 magnets10.1109/20.281024 ↗
28. The influence of Ga-substitution on the coercivity of Nd-(Fe,Co)-B sintered permanent magnets10.1109/20.104917 ↗
29. Microstructure of core-shell NdY-Fe-B sintered magnets with a high coercivity and excellent thermal stability10.1016/j.actamat.2020.05.038 ↗
30. Preparation and transmission electron microscope investigation of sintered Nd15.4Fe75.7B6.7Cu1.3Nb0.9 magnets10.1063/1.358293 ↗
31. Microstructure, magnetic properties, and corrosion behaviour of the copper-doped Nd-Fe-B sintered magnets10.1002/pssa.2211370115 ↗
32. The effects of blending additions of copper and cobalt to Nd16Fe76B8 milled powder to produce sintered magnets10.1016/S0304-8853(01)00067-1 ↗
33. Atomic-scale features of phase boundaries in hot deformed Nd–Fe–Co–B–Ga magnets infiltrated with a Nd–Cu eutectic liquid10.1016/j.actamat.2014.05.045 ↗
34. Distribution of Dy in high-coercivity (Nd,Dy)–Fe–B sintered magnet10.1016/j.actamat.2011.01.046 ↗
35. The origin of coercivity decrease in fine grained Nd–Fe–B sintered magnets10.1016/j.jmmm.2008.10.032 ↗
36. On the grain-boundary phase in iron rare-earth boron magnets10.1063/1.337849 ↗
37. Microstructure of fine-grained Nd–Fe–B sintered magnets with high coercivity10.1016/j.scriptamat.2011.05.006 ↗
38. Magnetism of ultrathin intergranular boundary regions in Nd–Fe–B permanent magnets10.1016/j.actamat.2014.03.013 ↗
39. Magnetic flux density measurements from grain boundary phase in 0.1 at% Ga-doped Nd–Fe–B sintered magnet10.1016/j.scriptamat.2019.12.030 ↗
40. Magnetism of Nd–Fe films as a model of grain boundary phase in Nd–Fe–B permanent magnets10.7567/APEX.9.013002 ↗
41. Magnetic ordering of the Nd6Fe13−xGa1+x (x=0,1) and Pr6Fe13−xGa1+x (x=0,1) compounds: a neutron diffraction study10.1016/S0925-8388(03)00183-X ↗
42. First-principles study on the magnetic properties of ordered Nd6(Fe,Ga)14 alloys10.1063/1.5007723 ↗
43. A new complex hexagonal phase in the Ce–Au–Sn system and its structure relationship with the 1/1 approximant10.1016/j.jallcom.2009.11.133 ↗
44. A new tetragonal phase in CoFeCrGe Heusler alloy10.1016/j.matchar.2017.12.036 ↗
45. A study on La2Mo2O9 decomposition process10.1007/s10853-012-6858-4 ↗
46. Computer programs for unit-cell determination in electron diffraction experiments10.1016/j.ultramic.2004.10.008 ↗
47. QtUCP-a program for determining unit-cell parameters in electron diffraction experiments using double-tilt and rotation-tilt holders10.1016/j.ultramic.2008.05.001 ↗
48. TEMUC3, a computer program for unit-cell determination of crystalline phases in TEM experiments10.1016/j.micron.2018.10.010 ↗
49. TRICE - A program for reconstructing 3D reciprocal space and determining unit-cell parameters10.1016/j.ultramic.2003.08.025 ↗
50. Kikuchi maps for hcp and bcc crystals10.1063/1.1708968 ↗
51. The transmission electron microscope
52. High-coercivity ultrafine-grained anisotropic Nd–Fe–B magnets processed by hot deformation and the Nd–Cu grain boundary diffusion process10.1016/j.actamat.2013.07.049 ↗
53. Enormous improvement of the coercivity of Ga and Cu co-doping Nd-Fe-B sintered magnet by post-sinter annealing10.1016/j.jallcom.2021.162418 ↗
54. Effect of non-rare-earth element enrichment on in-the-column secondary electron image contrast of Nd-rich phases in Nd-Fe-B sintered magnets
55. A study of the effects of heat treatment on the microstructures and magnetic properties of Cu-added Nd-Fe-B type sintered magnets10.1016/0925-8388(94)91086-3 ↗
56. Analytical TEM studies of Nd-Fe-B containing V, Co and Dy10.1016/0304-8853(92)90110-A ↗
57. The dependence of coercivity and corrosion resistance on grain size in Nd-Fe-B-type sintered permanent magnets
58. On the reversible and fully repeatable increase in coercive field of sintered Nd–Fe–B magnets following post sinter annealing10.1016/j.jmmm.2014.02.025 ↗
59. The role of Cu addition in the coercivity enhancement of sintered Nd-Fe-B permanent magnets10.1557/JMR.2009.0041 ↗
60. Improvement of coercivity of sintered NdFeB permanent magnets by heat treatment10.1016/S0304-8853(01)00967-2 ↗
61. An investigation of the microstructure in the grain boundary region of Nd–Fe–B sintered magnet during post-sintering annealing10.1016/j.scriptamat.2013.01.019 ↗
62. Transmission electron microscopy study on Nd-rich phase and grain boundary structure of Nd–Fe–B sintered magnets10.1063/1.1851017 ↗
63. The mechanism of coercivity enhancement by the grain boundary diffusion process of Nd–Fe–B sintered magnets10.1016/j.actamat.2012.12.018 ↗
64. Effect of Nd content on the microstructure and coercivity of hot-deformed Nd–Fe–B permanent magnets10.1016/j.actamat.2013.05.027 ↗
65. Temperature-dependent magnetization reversal process and coercivity mechanism in Nd-Fe-B hot-deformed magnets10.1063/1.4937274 ↗