Interfacial microstructure of Nd 2Fe 14B/Nd-Rich and coercivity in Nd-Fe-B films

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Abstract

This study provides the relationship between phase change of Nd-rich and microstructural changes of Nd 2Fe 14B/Nd-rich interface in Nd-Fe-B films with different coercivity values. In as-deposited Nd-Fe-B film, flat interface of Nd 2Fe 14B/dhcp Nd is mainly observed. After oxidation, oxidized region was observed at the surface of Nd 2Fe 14B phase, and Nd 2Fe 14B/fcc NdO x interface were observed. In the Nd-Fe-B film subsequently annealed at 350°C after oxidation, the coercivity of which decreases to around 20% of the value of as-deposited film, and the hep Nd 2O 3 phase exists dominantly at the surface of Nd 2Fe 14B phase. In addition, there are some damaged regions at the surface of Nd 2Fe 14B phase. On the contrary, both the metastable C-Nd 2O 3 and amorphous phases existed dominantly at the Nd 2Fe 14B/Nd-rich interface of the film annealed at 650°C. The coercivity of this film recovered to the same value of as-deposited film. These results indicate that the crystallization of hep Nd 2O 3 phase include some damages to neighboring Nd 2Fe 14B phase decrease coercivity. During annealing at 550 to 650°C, Nd-rich liquid phase appears and modifies the surface of Nd 2Fe 14B, and the coercivity recovers. After cooling, this liquid phase seems to crystallize into a C-Nd 2O 3 or an amorphous phases at the surface of Nd 2Fe 14B phase. In other words, the C-Nd 2O 3 or amorphous phases can exist without decreasing coercivity.

Original languageEnglish
Pages (from-to)65-71
Number of pages7
JournalNippon Kinzoku Gakkaishi/Journal of the Japan Institute of Metals
Volume76
Issue number1
DOIs
Publication statusPublished - 2012 Jan 1

Keywords

  • Coercivity
  • Microstructure
  • Neodymium-iron-boron films
  • Oxidation

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Mechanics of Materials
  • Metals and Alloys
  • Materials Chemistry

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