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Grain boundary oxide layers in NdFeB-based permanent magnets

Mazilkin, A. 1; Straumal, B. B. 1; Protasova, S. G.; Gorji, S. 1; Straumal, A. B.; Katter, M.; Schütz, G.; Barezky, B. 1
1 Karlsruher Institut für Technologie (KIT)


The microstructure of grain boundaries (GBs) in the commercial NdFeB-based alloy for permanent magnets has been studied. It is generally accepted that the unique hard magnetic properties of such alloys are controlled by the thin layers of a Nd-rich phase in Nd$_{2}$Fe$_{14}$B/Nd$_{2}$Fe$_{14}$B GBs. These GB layers ensure the magnetic isolation of Nd$_{2}$Fe$_{14}$B grains from each other. It is usually supposed that such GB layers contain metallic Nd or Nd-rich intermetallic compounds. However, the commercial NdFeB-based permanent magnets frequently contain a tangible amount of neodymium oxide Nd$_{2}$O$_{3}$ at the triple junctions between Nd$_{2}$Fe$_{14}$B grains. The goal of this work was to check whether the Nd$_{2}$Fe$_{14}$B/Nd$_{2}$Fe$_{14}$B GBs could also contain the thin layers of Nd$_{2}$O$_{3}$ oxide phase. Indeed, the screening with EELS-based elemental analysis permitted to observe that some of these Nd-rich layers in Nd$_{2}$Fe$_{14}$B/Nd$_{2}$Fe$_{14}$B GBs contain not only neodymium, but also oxygen. More detailed analysis of such GBs with high-resolution transmission electron microscopy (HR TEM) showed these GB layers are crystalline and have the lattice of neodymium oxide Nd$_{2}$O$_{3}$. ... mehr

Verlagsausgabe §
DOI: 10.5445/IR/1000134564
Veröffentlicht am 30.06.2021
DOI: 10.1016/j.matdes.2020.109417
Zitationen: 47
Web of Science
Zitationen: 50
Zitationen: 50
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 02.2021
Sprache Englisch
Identifikator ISSN: 0264-1275
KITopen-ID: 1000134564
HGF-Programm 43.31.01 (POF IV, LK 01) Multifunctionality Molecular Design & Material Architecture
Erschienen in Materials and design
Verlag Elsevier
Band 199
Seiten Art.-Nr.: 109417
Schlagwörter Permanent magnets; Coercivity; Nd-Fe-B alloys; Oxide layers; Grain boundaries; Thin layers
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