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

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 proceeding › Conference 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 language	English
Title of host publication	Euro PM 2019 Congress and Exhibition
Publisher	European Powder Metallurgy Association (EPMA)
ISBN (Electronic)	9781899072514
Publication status	Published - 2019
Externally published	Yes
Event	European Powder Metallurgy Congress and Exhibition, Euro PM 2019 - Maastricht, Netherlands Duration: 2019 Oct 13 → 2019 Oct 16

Publication series

Name	Euro PM 2019 Congress and Exhibition

Conference

Conference	European Powder Metallurgy Congress and Exhibition, Euro PM 2019
Country/Territory	Netherlands
City	Maastricht
Period	19/10/13 → 19/10/16

ASJC Scopus subject areas

Metals and Alloys
Surfaces, Coatings and Films
Surfaces and Interfaces

Cite this

Preparation of highly anisotropic NdFeB powders and enhancing their coercivity by the dy-free grain boundary diffusion process. / Huang, H. S.; Sepehri-Amin, H.; Ohkubo, T.; Chiu, C. H.; Chen, P. W.; Mo, C. C.

Euro PM 2019 Congress and Exhibition. European Powder Metallurgy Association (EPMA), 2019. (Euro PM 2019 Congress and Exhibition).

Research output: Chapter in Book/Report/Conference proceeding › Conference contribution

Huang, HS, Sepehri-Amin, H, Ohkubo, T, Chiu, CH, Chen, PW & Mo, CC 2019, Preparation of highly anisotropic NdFeB powders and enhancing their coercivity by the dy-free grain boundary diffusion process. in Euro PM 2019 Congress and Exhibition. Euro PM 2019 Congress and Exhibition, European Powder Metallurgy Association (EPMA), European Powder Metallurgy Congress and Exhibition, Euro PM 2019, Maastricht, Netherlands, 19/10/13.

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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.",

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AU - Huang, H. S.

AU - Sepehri-Amin, H.

AU - Ohkubo, T.

AU - Chiu, C. H.

AU - Chen, P. W.

AU - Mo, C. C.

PY - 2019

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N2 - 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.

AB - 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.

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M3 - Conference contribution

AN - SCOPUS:85101983302

T3 - Euro PM 2019 Congress and Exhibition

BT - Euro PM 2019 Congress and Exhibition

PB - European Powder Metallurgy Association (EPMA)

T2 - European Powder Metallurgy Congress and Exhibition, Euro PM 2019

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ER -

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

Abstract

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