Effects of Al/Cu co-doping on crystal structure and chemical composition of Nd-rich phases in Nd-Fe-B sintered magnet

Tae Hoon Kim, Seong Rae Lee, Kyoung Hoon Bae, Hyo Jun Kim, Min Woo Lee, Tae Suk Jang

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We investigated the effects of Al/Cu co-doping on the magnetic and microstructural properties of a Nd-Fe-B sintered magnet. In particular, the structural and compositional changes of Cu-dissolved Nd-rich (Cu-rich) triple junction phase (TJP) and grain boundary phase (GBP) experienced upon Al/Cu co-doping were intensively analyzed. Al was selectively dissolved into the Culow-rich phases (B phase, 3–15 at.% Cu) other than the Cuhigh-rich phases (A phase, 20–45 at.% Cu). The B phase with an h-Nd2O3 structure was transformed to the C phase (Al-dissolved Culow-rich phases) with a c-Nd2O3 structure upon Al dissolution. In addition, the continuity of C GBP was improved and the Fe content of C GBP was reduced (25 → 5 at.% Fe). As a result, the coercivity (Hc) of the Al/Cu co-doped magnet was higher than that of a Cu-doped magnet. The critical role played by Al in improving the magnetic properties and microstructure of the Al/Cu co-doped magnet was elucidated. The detailed mechanism for the Hc enhancement of the Al/Cu co-doped magnet was discussed based on the results.

Original languageEnglish
Pages (from-to)200-207
Number of pages8
JournalActa Materialia
Publication statusPublished - 2017 Jul 1



  • Coercivity
  • Grain boundaries
  • Metastable phases
  • Microstructures
  • Nd-Fe-B sintered magnet
  • Triple junctions

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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