Identification of 2:17R' Cell Edge Phase in Sm2Co17-Type Permanent Magnets by Transmission Electron Microscopy
Received date: 2020-10-16
Revised date: 2021-02-02
Online published: 2021-03-03
Supported by
National Natural Science Foundation of China(52071256);Open Project of State Key Laboratory for Mechanical Behavior of Materials(20192106)
Pinning-controlled Sm2(Co, M)17 (M = Fe, Cu, and Zr) magnets with cellular nanostructures are the strongest high-temperature permanent magnets. The squareness factor of such magnets is smaller than those of nucleation-controlled permanent magnets, leading to a lower-than-ideal maximum energy product. One of the main reasons for this poor squareness is that the pinning strength is weaker at cell edges than at 1:5H cell boundaries. However, the structure of these edges remains a topic of debate. To identify the microstructure of cell edges, electron diffraction, TEM bright/dark field imaging, and HRTEM imaging on a model magnet Sm25Co50.2Fe16.2Cu5.6Zr3.0 (mass fraction, %) were performed using both [100]2:17R and [101]2:17R zone axes. The results revealed a rhombohedral 2:17R' phase at some of the edges, with one faulting basal layer in the 2:17R lattice. Further comparative investigations revealed that all the extra superlattice reflections result from the 2:17R' phase, excluding the previously identified 2:17H or Smn + 1Co5n - 1 or their mixture that can only produce a part of such superlattice reflections. Owing to the 2:17R' phase with a faulted basal plane, the free energy at the cell edges is higher than that of the 2:17R cell interiors, leading to repulsive domain-wall-pinning unfavorable for the squareness factor. This study provides important evidence for understanding the microstructural origin of the poor squareness factor obtained for Sm2(Co, M)17 permanent magnets.
Key words： permanent magnet; Sm-Co magnet; electron diffraction; defect; TEM characterization
Hongyu CHEN , Xin SONG , Xianglong ZHOU , Wentao JIA , Tao YUAN , Tianyu MA . Identification of 2:17R' Cell Edge Phase in Sm2Co17-Type Permanent Magnets by Transmission Electron Microscopy[J]. Acta Metall Sin, 2021 , 57(12) : 1637 -1644 . DOI: 10.11900/0412.1961.2020.00412
| 1 | Ojima T, Tomizawa S, Yoneyama T, et al. Magnetic properties of a new type of rare-earth cobalt magnets Sm2(Co, Cu, Fe, M)17 [J]. IEEE Trans. Magn., 1977, 13: 1317 |
| 2 | Buschow K H J. New developments in hard magnetic materials [J]. Rep. Prog. Phys., 1991, 54: 1123 |
| 3 | Zhu M G, Sun W, Fang Y K, et al. The research progress and status of Sm-Co permanent magnet materials [J]. Mater. China, 2015, 34: 789 |
| 3 | 朱明刚, 孙 威, 方以坤等. Sm2Co17基永磁材料的研究进展 [J]. 中国材料进展, 2015, 34: 789 |
| 4 | Liu J P, Fullerton E, Gutfleisch O, et al. Nanoscale Magnetic Materials and Applications [M]. New York: Springer, 2009: 337 |
| 5 | Coey J M D. Permanent magnets: Plugging the gap [J]. Scr. Mater., 2012, 67: 524 |
| 6 | Strnat K J. The hard-magnetic properties of rare earth-transition metal alloys [J]. IEEE Trans. Magn., 1972, 8: 511 |
| 7 | Horiuchi Y, Hagiwara M, Endo M, et al. Influence of intermediate-heat treatment on the structure and magnetic properties of iron-rich Sm(Co, Fe, Cu, Zr)z sintered magnets [J]. J. Appl. Phys., 2015, 117: 17C704 |
| 8 | Goll D, Kronmüller H, Stadelmaier H H. Micromagnetism and the microstructure of high-temperature permanent magnets [J]. J. Appl. Phys., 2004, 96: 6534 |
| 9 | Skomski R. Domain-wall curvature and coercivity in pinning type Sm-Co magnets [J]. J. Appl. Phys., 1997, 81: 5627 |
| 10 | Katter M, Weber J, Assmus W, et al. A new model for the coercivity mechanism of Sm2(Co, Fe, Cu, Zr)17 magnets [J]. IEEE Trans. Magn., 1996, 32: 4815 |
| 11 | Kronmüller H, Goll D. Micromagnetic analysis of pinning-hardened nanostructured, nanocrystalline Sm2Co17 based alloys [J]. Scr. Mater., 2002, 47: 545 |
| 12 | Gong S T, Jiang C B, Zhang T L. Effect of Fe on microstructure and coercivity of SmCo-based magnets [J]. Acta Metall. Sin., 2017, 53: 726 |
| 12 | 巩劭廷, 蒋成保, 张天丽. Fe对SmCo基高温永磁体微观结构及矫顽力的影响 [J]. 金属学报, 2017, 53: 726 |
| 13 | Xiong X Y, Ohkubo T, Koyama T, et al. The microstructure of sintered Sm(Co0.72Fe0.20Cu0.055Zr0.025)7.5 permanent magnet studied by atom probe [J]. Acta Mater., 2004, 52: 737 |
| 14 | Xia W, He Y K, Huang H B, et al. Initial irreversible losses and enhanced high-temperature performance of rare-earth permanent magnets [J]. Adv. Funct. Mater., 2019, 29: 1900690 |
| 15 | Xu C, Wang H, Zhang T L, et al. Correlation of microstructure and magnetic properties in Sm(CobalFe0.1Cu0.1Zr0.033)6.93 magnets solution-treated at different temperatures [J]. Rare Met., 2019, 38: 20 |
| 16 | Guo Z H, Li W. Room- and high-temperature magnetic properties of Sm(CobalFexCu0.088Zr0.025)7.5 (x = 0-0.30) sintered magnets [J]. Acta Metall. Sin., 2002, 38: 866 |
| 16 | 郭朝晖, 李 卫. Sm(CobalFexCu0.088Zr0.025)7.5 (x = 0~0.30)烧结永磁体的磁性及其高温特性 [J]. 金属学报, 2002, 38: 866 |
| 17 | Machida H, Fujiwara T, Kamada R, et al. The high squareness Sm-Co magnet having Hcb = 10.6 kOe at 150oC [J]. AIP Adv., 2017, 7: 056223 |
| 18 | Zhou X L, Song X, Jia W T, et al. Identifications of SmCo5 and Smn + 1Co5n - 1-type phases in 2:17-type Sm-Co-Fe-Cu-Zr permanent magnets [J]. Scr. Mater., 2020, 182: 1 |
| 19 | Wang Y Q, Yue M, Wu D, et al. Microstructure modification induced giant coercivity enhancement in Sm(CoFeCuZr)z permanent magnets [J]. Scr. Mater., 2018, 146: 231 |
| 20 | Yan G H, Xia W X, Liu Z, et al. Effect of grain boundary on magnetization behaviors in 2:17 type SmCo magnet [J]. J. Magn. Magn. Mater., 2019, 489: 165459 |
| 21 | Rabenberg L, Mishra R K, Thomas G. Microstructures of precipitation-hardened SmCo permanent magnets [J]. J. Appl. Phys., 1982, 53: 2389 |
| 22 | Duerrschnabel M, Yi M, Uestuener K, et al. Atomic structure and domain wall pinning in samarium-cobalt-based permanent magnets [J]. Nat. Commun., 2017, 8: 54 |
| 23 | Horiuchi Y, Hagiwara M, Okamoto K, et al. Effect of pre-aging treatment on the microstructure and magnetic properties of Sm(Co, Fe, Cu, Zr)7.8 sintered magnets [J]. Mater. Trans., 2014, 55: 482 |
| 24 | Fidler J, Skalicky P, Rothwarf F. High resolution electron microscope study of Sm(Co, Fe, Cu, Zr)7.5 magnets [J]. IEEE Trans. Magn., 1983, 19: 2041 |
| 25 | Maury C, Rabenberg L, Allibert C H. Genesis of the cell microstructure in the Sm(Co, Fe, Cu, Zr) permanent magnets with 2:17 type [J]. Phys. Status. Solidi, 1993, 140A: 57 |
| 26 | Feng H B, Chen H S, Guo Z H, et al. Twinning structure in Sm(Co, Fe, Cu, Zr)z permanent magnet [J]. Intermetallics, 2010, 18: 1067 |
| 27 | Delannay F, Derkaoui S, Allibert C H. The influence of zirconium on Sm(CoFeCuZr)7.2 alloys for permanent magnets I: Identification of the phases by transmission electron microscopy [J]. J. Less-Common. Met., 1987, 134: 249 |
| 28 | Xu C, Wang H, Liu B J, et al. The formation mechanism of 1:5H phase in Sm(Co, Fe, Cu, Zr)z melt-spun ribbons with high iron content [J]. J. Magn. Magn. Mater., 2020, 496: 165939 |
| 29 | Song X, Zhou X L, Yuan T, et al. Role of nanoscale interfacial defects on magnetic properties of the 2:17-type Sm-Co permanent magnets [J]. J. Alloys Compd., 2020, 816: 152620 |
| 30 | Jia W T, Zhou X L, Xiao A D, et al. Defects-aggregated cell boundaries induced domain wall curvature change in Fe-rich Sm-Co-Fe-Cu-Zr permanent magnets [J]. J. Mater. Sci., 2020, 55: 13258 |
| 31 | Song X, Ma T Y, Zhou X L, et al. Atomic scale understanding of the defects process in concurrent recrystallization and precipitation of Sm-Co-Fe-Cu-Zr alloys [J]. Acta Mater., 2021, 202: 290 |
| 32 | Song X, Liu Y, Xiao A D, et al. Cell-boundary-structure controlled magnetic-domain-wall-pinning in 2:17-type Sm-Co-Fe-Cu-Zr permanent magnets [J]. Mater. Charact., 2020, 169: 110575 |
| 33 | Rabenberg L, Mishra R, Thomas G. Development of the cellular microstructure in the SmCo7.4-type magnets [A]. The Proceeding 6th International Workshop on Rare Earth-Cobalt Permanent Magnets and Their Applications [C]. Australia: JOSEF FIDLER, Druckerei Lischkar & Co A-1120 Vienna, 1982: 599 |
| 34 | Chen H S, Wang Y Q, Yao Y, et al. Attractive-domain-wall-pinning controlled Sm-Co magnets overcome the coercivity-remanence trade-off [J]. Acta Mater., 2019, 164: 196 |
| 35 | Tian Y, Liu Z, Xu H, et al. In situ observation of domain wall pinning in Sm(Co, Fe, Cu, Zr)z magnet by Lorentz microscopy [J]. IEEE Trans. Magn., 2015, 51: 2102404 |
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