Mechanism of the texture development in hydrogen-disproportionation-desorption-recombination (HDDR) processed Nd-Fe-B powders

H. Sepehri-Amin, T. Ohkubo, K. Hono, K. Güth, O. Gutfleisch

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Microstructure evolution in Nd12.8Fe80.1B6.6Ga0.3Nb0.2 alloy powders at different hydrogen pressures during the hydrogen-disproportionation process PH2HD has been studied in order to understand the underlying mechanism of the texture development during the dynamic hydrogen-disproportionation-desorption-recombination (d-HDDR) process. Transmission electron microscopy showed that Fe2B grains "memorize" the crystallographic orientation of the initial Nd2Fe14B phase and transfer it to the recombined Nd2Fe14B grains in the highly textured sample. 3-D tomography of backscattered electron SEM images showed that recombined Nd2Fe14B grains nucleate at the interfaces of Fe2B/NdH2 phases, which grow through the interfaces of NdH2/α-Fe phases during the DR process. Boron segregation was found at the NdH2/α-Fe interfaces, which serve as a boron source for the growth of the recombined Nd2Fe14B grains. The mechanism of the texture development is discussed based on the microstructure observations and the corresponding evolution of magnetic properties.

Original languageEnglish
Pages (from-to)42-52
Number of pages11
JournalActa Materialia
Volume85
DOIs
Publication statusPublished - 2015 Feb 15
Externally publishedYes

Keywords

  • Microstructure
  • Nd-Fe-B permanent magnets
  • Texture
  • d-HDDR process

ASJC Scopus subject areas

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

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