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Microstructure and magnetic properties of melt-spun Alnico-5 alloys

Löwe, Konrad and Dürrschnabel, Michael and Molina-Luna, Leopoldo and Madugundo, Rajasekhar and Frincu, Bianca and Kleebe, Hans-Joachim and Gutfleisch, Oliver and Hadjipanayis, George C. (2016):
Microstructure and magnetic properties of melt-spun Alnico-5 alloys.
In: Journal of Magnetism and Magnetic Materials, ELSEVIER SCIENCE BV, pp. 230-234, 407, ISSN 03048853, [Online-Edition: http://dx.doi.org/10.1016/j.jmmm.2015.12.092],
[Article]

Abstract

The aim of this work is to investigate the effect of very fine grain sizes on the spinodal decomposition in the Alnico system. Commercial Alnico 5 was melted and melt-spun with varying copper wheel speeds, which led to a grain size of 1-2 mu m. This value was further reduced to sub-micrometer size by a small addition of Boron (1 at%). The spinodal decomposition was induced through a two-step annealing treatment under magnetic field in the range of 600-900 degrees C. It was found that the size of the spinodal structures is not influenced much by increased wheel speeds but becomes smaller with the addition of Boron. However, the difference in coercivity between the samples with and without Boron is only 50 Oe (4 kA/m). To study the influence of the annealing treatment two sets of samples are compared, one with the highest coercivity (366 Oe/29 kA/m) and the other one with lower coercivity (180 0e/14.5 kA/m). We found with Scanning transmission electron microscopy Energy-dispersive X-ray spectroscopy (STEM EDX) a much sharper chemical interface between the al and oc2 precipitates in the former sample, which we attribute to be the main reason for the higher coercivity. (C) 2016 Elsevier B.V. All rights reserved.

Item Type: Article
Erschienen: 2016
Creators: Löwe, Konrad and Dürrschnabel, Michael and Molina-Luna, Leopoldo and Madugundo, Rajasekhar and Frincu, Bianca and Kleebe, Hans-Joachim and Gutfleisch, Oliver and Hadjipanayis, George C.
Title: Microstructure and magnetic properties of melt-spun Alnico-5 alloys
Language: English
Abstract:

The aim of this work is to investigate the effect of very fine grain sizes on the spinodal decomposition in the Alnico system. Commercial Alnico 5 was melted and melt-spun with varying copper wheel speeds, which led to a grain size of 1-2 mu m. This value was further reduced to sub-micrometer size by a small addition of Boron (1 at%). The spinodal decomposition was induced through a two-step annealing treatment under magnetic field in the range of 600-900 degrees C. It was found that the size of the spinodal structures is not influenced much by increased wheel speeds but becomes smaller with the addition of Boron. However, the difference in coercivity between the samples with and without Boron is only 50 Oe (4 kA/m). To study the influence of the annealing treatment two sets of samples are compared, one with the highest coercivity (366 Oe/29 kA/m) and the other one with lower coercivity (180 0e/14.5 kA/m). We found with Scanning transmission electron microscopy Energy-dispersive X-ray spectroscopy (STEM EDX) a much sharper chemical interface between the al and oc2 precipitates in the former sample, which we attribute to be the main reason for the higher coercivity. (C) 2016 Elsevier B.V. All rights reserved.

Journal or Publication Title: Journal of Magnetism and Magnetic Materials
Volume: 407
Publisher: ELSEVIER SCIENCE BV
Uncontrolled Keywords: Alnico, Melt-spinning, Spinodal decomposition, Coercivity, Heat treatment
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Advanced Electron Microscopy (aem)
11 Department of Materials and Earth Sciences > Material Science > Functional Materials
Date Deposited: 11 May 2016 12:32
Official URL: http://dx.doi.org/10.1016/j.jmmm.2015.12.092
Identification Number: doi:10.1016/j.jmmm.2015.12.092
Funders: Part of the work was supported by DOE BES (DE-FG02-04ER4612)., The authors also acknowledge financial support from the Hessen State Ministry of Higher Education, Research and the Arts via LOEWE RESPONSE., The Jeol JEM 2100F transmission electron microscope used in this work was partially funded by the German Research Foundation (DFG/INST163/2951).
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