Preparation of highly anisotropic NdFeB powders and enhancing their coercivity by the dy-free grain boundary diffusion process

H. S. Huang, H. Sepehri-Amin, T. Ohkubo, C. H. Chiu, P. W. Chen, C. C. Mo

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Hydrogenation-disproportionation-desorption-recombination (HDDR) and grain boundary diffusion (GBD) were employed to prepare NdFeB powders with high anisotropy and coercivity. First, this study investigated the key conditions of HDDR process for obtaining highly anisotropic NdFeB powders. By optimizing all the HDDR parameters, the highest anisotropy of HDDR powders with a remanence of 1.46T was achieved. Next, Nd80Cu20, Nd80Ga15Cu5, and Pr60Cu20Al10Ni10 Dy-free alloys were used as diffusion sources for GBD to enhance the coercivity of the HDDR powders. The coercivity increment of GBD was strongly influenced by the HD time of HDDR process. A longer HD time of 150min contributed the coercivity increment (∆iHc) about 4.2kOe after the GBD treatment, while the ∆iHc of 30min HD time only reached 0.8kOe. Although Pr60Cu20Al10Ni10 exhibited the best coercivity enhancement among the three diffusion sources, the thermal stability of the GBD treated powders by Pr60Cu20Al10Ni10 was inferior compared to that of Nd80Cu20 and Nd80Ga15Cu5.

Original languageEnglish
Title of host publicationEuro PM 2019 Congress and Exhibition
PublisherEuropean Powder Metallurgy Association (EPMA)
ISBN (Electronic)9781899072514
Publication statusPublished - 2019
Externally publishedYes
EventEuropean Powder Metallurgy Congress and Exhibition, Euro PM 2019 - Maastricht, Netherlands
Duration: 2019 Oct 132019 Oct 16

Publication series

NameEuro PM 2019 Congress and Exhibition

Conference

ConferenceEuropean Powder Metallurgy Congress and Exhibition, Euro PM 2019
CountryNetherlands
CityMaastricht
Period19/10/1319/10/16

ASJC Scopus subject areas

  • Metals and Alloys
  • Surfaces, Coatings and Films
  • Surfaces and Interfaces

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