Special microstructure evolution and enhanced magnetic properties of Ce-Fe-B-based spark plasma sintered magnets with core-shell structure by NdCu addition
| Autor: | Zhenchen Zhong, Shengcan Ma, Sajjad Ur Rehman, Qingzheng Jiang, Renhui Liu, Qingwen Zeng, Weikai Lei, Lunke He, Lili Zhang |
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| Rok vydání: | 2019 |
| Předmět: |
Materials science
Condensed matter physics Mechanical Engineering Metals and Alloys Spark plasma sintering 02 engineering and technology Coercivity 010402 general chemistry 021001 nanoscience & nanotechnology Microstructure 01 natural sciences 0104 chemical sciences Lattice constant Mechanics of Materials Remanence Phase (matter) Magnet Materials Chemistry Curie temperature 0210 nano-technology |
| Zdroj: | Journal of Alloys and Compounds. 775:449-456 |
| ISSN: | 0925-8388 |
| DOI: | 10.1016/j.jallcom.2018.10.114 |
| Popis: | Ce-Fe-B-based rare earth permanent magnets are prepared by spark plasma sintering (SPS) technique, and low melting NdCu alloy is added to improve its magnetic properties and thermal stabilities. The X-ray diffraction (XRD) result indicates that the lattice constants of the unit cell of 2:14:1 phase increase with NdCu addition. The remanent magnetization, coercivity and maximum energy product are enhanced remarkably from 0.37 T, 227 kA/m, 16 kJ/m3 for the sintered magnets without NdCu addition to 0.47 T, 476 kA/m, 30 kJ/m3 for those with 20 wt% NdCu addition. The temperature coefficients of remanence (α) and coercivity (β) of the spark plasma sintered magnets (denoted as SPSed magnets thereafter) are improved from −0.46%/K, −0.60%/K to −0.34%/K, −0.55%/K in the range of 300–400 K. There are two Curie temperatures in the Ce-based magnets with NdCu addition, which implies the coexistence of two hard magnetic phases. The second Curie temperature depends on the NdCu content. It is shown by the microstructure analysis that a typical core-shell structure is formed with Ce-rich core and Ce-lean shell by NdCu addition. Furthermore, it is displayed that Nd atoms prefer to diffuse into the Ce-lean flakes. The Nd-Ce exchange mechanism and immigration behavior of elements are finally investigated. The intergranular exchange coupling strength is enhanced in NdCu-added magnet. It is found out that the core-shell structure plays an important role in the special microstructure evolution and the enhancement of the magnetic properties for the typical Ce-Fe-B-based SPSed magnets by NdCu addition. |
| Databáze: | OpenAIRE |
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