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Title: Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders

Abstract

We presented some considerations for achieving high degree of alignment in polymer bonded permanent magnets via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. Moreover, the thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees with an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Finally, manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.

Authors:
 [1];  [2];  [2];  [1];  [3];  [1];  [2]
  1. Ames Lab., Ames, IA (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ames Laboratory (AMES), Ames, IA (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Advanced Manufacturing Office (EE-5A)
OSTI Identifier:
1376655
Report Number(s):
LLNL-JRNL-698023; IS-J-9071
Journal ID: ISSN 0304-8853
Grant/Contract Number:
AC52-07NA27344; AC02-07CH11358; AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of Magnetism and Magnetic Materials
Additional Journal Information:
Journal Volume: 422; Journal Issue: C; Journal ID: ISSN 0304-8853
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; polymer binders; high performance bonded magnets

Citation Formats

Nlebedim, I. C., Ucar, Huseyin, Hatter, Christine B., McCallum, R. W., McCall, Scott K., Kramer, M. J., and Paranthaman, M. Parans. Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders. United States: N. p., 2016. Web. doi:10.1016/j.jmmm.2016.08.090.
Nlebedim, I. C., Ucar, Huseyin, Hatter, Christine B., McCallum, R. W., McCall, Scott K., Kramer, M. J., & Paranthaman, M. Parans. Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders. United States. doi:10.1016/j.jmmm.2016.08.090.
Nlebedim, I. C., Ucar, Huseyin, Hatter, Christine B., McCallum, R. W., McCall, Scott K., Kramer, M. J., and Paranthaman, M. Parans. 2016. "Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders". United States. doi:10.1016/j.jmmm.2016.08.090. https://www.osti.gov/servlets/purl/1376655.
@article{osti_1376655,
title = {Studies on in situ magnetic alignment of bonded anisotropic Nd-Fe-B alloy powders},
author = {Nlebedim, I. C. and Ucar, Huseyin and Hatter, Christine B. and McCallum, R. W. and McCall, Scott K. and Kramer, M. J. and Paranthaman, M. Parans},
abstractNote = {We presented some considerations for achieving high degree of alignment in polymer bonded permanent magnets via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. Moreover, the thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees with an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Finally, manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.},
doi = {10.1016/j.jmmm.2016.08.090},
journal = {Journal of Magnetism and Magnetic Materials},
number = C,
volume = 422,
place = {United States},
year = 2016,
month = 8
}

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  • We presented some considerations for achieving high degree of alignment in polymer bonded permanent magnets via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. Moreover, the thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees withmore » an observed correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Finally, manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.« less
  • Considerations for achieving high degree of alignment in polymer bonded permanent magnets are presented via the results of a study on in situ magnetic alignment of anisotropic Nd-Fe-B magnet powders. Contributions from effect of the alignment temperature, alignment magnetic field and the properties of the polymer on the hard magnetic properties of the bonded magnet were considered. The thermo-rheological properties of the polymer and the response of the magnet powders to the applied magnetic field indicate that hard magnetic properties were optimized at an alignment temperature just above the melting temperature of the EVA co-polymer. This agrees with an observedmore » correlation between the change in magnetization due to improved magnetic alignment of the anisotropic powders and the change in viscosity of the binder. Manufacturing cost can be minimized by identifying optimum alignment temperatures and magnetic field strengths.« less
  • Recent progress in the understanding of the texture formation mechanism in the hydrogenation-disproportionation-desorption-recombination (HDDR) process, improvements of stability with regard to thermal and structural losses, and the state-of-the-art performance of both compression and injection molded magnets made from the newly developed anisotropic HDDR powders are reported. Transmission electron microscopy observations of disproportionated Nd{endash}Fe{endash}Co{endash}Ga{endash}Zr{endash}B alloys have revealed the existence of finely dispersed crystallites of Nd{sub 2}(Fe,Co,Ga){sub 14}B which have a common crystallographic orientation. It is proposed that, upon removal of hydrogen, the hydrogen-disproportionated structure recombines from these crystallites to form textured submicron crystallites of the 2:14:1 phase. Using highly anisotropic HDDRmore » powders, energy products (BH){sub max} exceeding 170 kJ/m{sup 3} (21 MGOe) have been obtained on compression-molded resin-bonded magnets and 130 kJ/m{sup 3} (16 MGOe) on injection-molded ones. High coercivity HDDR powders with an intrinsic coercivity (H{sub cJ}) exceeding 1.27 MA/m (16 kOe) have also been obtained by replacing part of Nd with Dy, which enabled improvement of thermal stability. It is shown that the degradation of magnetic performance of resin-bonded HDDR magnets is prevented by eliminating pore formation during the molding process. {copyright} {ital 1997 American Institute of Physics.}« less
  • The microstructure of Sm(Co{sub bal}Fe{ital {sub x}}Cu{sub 0.08}Zr{sub 0.03}){sub 8.2}, where {ital x}=0.23, 0.26, and 0.28, in the as-cast state and after various processing stages has been examined by optical microscopy. The size of the 2:17 matrix phase was found to be approximately 100 {mu}m in the as-cast state. A slight increase in the size of the 2:17 matrix was observed after thermal processing. Subgrains of 10 to 20 {mu}m are present in the 2:17 matrix of the fully processed ingots. Powders with a mean particle size range of 3{endash}300 {mu}m were found to exhibit a Gaussian distribution. A slightmore » increase in intrinsic coercivity ({ital H{sub ci})} was observed when the mean particle size was decreased from 300 to 200 {mu}m and remained nearly constant for sizes ranging between 10 and 200 {mu}m. A significant decrease in {ital H{sub ci}} was observed when powders were further reduced below 10 {mu}m. Similar trends were also observed for remanence ({ital B{sub r}}), maximum energy product ({ital BH}{sub max}), and squareness of the second quadrant demagnetization curve. The size of the subgrains was found to be critical to these properties. The {ital H{sub ci}} of alloy powders with a high Fe content appeared to degrade more severely when reduced below 10 {mu}m. For a fixed mean particle size, alloy powders with a high Fe content also exhibited a less-square second quadrant demagnetization curve. A {ital B{sub r}} of 9.2 kG, {ital H{sub ci}} of 18 kOe, {ital H{sub cb}} of 7.4 kOe, {ital BH}{sub max} of 19 MGOe, and a squareness ratio of 0.91 have been obtained on Sm(Co{sub bal}Fe{sub 0.23}Cu{sub 0.08}Zr{sub 0.03}){sub 8.2}. As expected for alloys with a higher Fe content, {ital B{sub r}} of 11.3 kG, {ital H{sub ci}} of 20 kOe, {ital H{sub cb}} of 8.1 kOe, {ital BH}{sub max} of 25 MGOe, and a square ratio of 0.83 have been obtained on Sm(Co{sub bal}Fe{sub 0.28}Cu{sub 0.08}Zr{sub 0.03}){sub 8.2}. {copyright} {ital 1997 American Institute of Physics.}« less