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On the synthesis and microstructure analysis of high performance MnBi

Chen, Yu-Chun and Sawatzki, Simon and Ener, Semih and Sepehri-Amin, Hossein and Leineweber, Andreas and Gregori, Giuliano and Qu, Fei and Muralidhar, Shreyas and Ohkubo, Tadakatsu and Hono, Kazuhiro and Gutfleisch, Oliver and Kronmüller, Helmut and Schütz, Gisela and Goering, Eberhard (2016):
On the synthesis and microstructure analysis of high performance MnBi.
In: AIP Advances, AIP Publishing, p. 125301, 6, (12), ISSN 2158-3226,
[Online-Edition: http://dx.doi.org/10.1063/1.4971759],
[Article]

Abstract

Highly anisotropic MnBi powder with over 90 wt% low-temperature phase can be prepared using conventional arc-melting and 2 hour-low energy ball milling (BM) followed by magnetic separation. After proper alignment, the purified Mn55Bi45(Mn45Bi55) powder show remarkable magnetic properties: mass remanence of 71(65) Am2/kg and coercivity of 1.23(1.18) T at 300 K. The nominal maximum energy product of 120 kJ/m3 is achieved in the purified 2h-BM Mn55Bi45 powder, close to theoretical value of 140.8 kJ/m3. The Mn55Bi45(Mn45Bi55) bulk magnets show the highest volume remanence of 0.68(0.57) T at 300 K, while they were consolidated at 573(523) K by a pressure of 200 MPa for 5 minutes using hot-compaction method. In addition to the observed grain size, the coercivity of the hot-compacted samples at 300 K was found to be strongly related to the amount of metallic Mn and Bi residue at the grain-boundary. Our study proves that the magnetic properties of the Mn45Bi55 bulk magnets are stable up to 500 K, and the nominal (BH)max values are still above 40 kJ/m3 at 500 K showing the potential ability for high-temperature applications.

Item Type: Article
Erschienen: 2016
Creators: Chen, Yu-Chun and Sawatzki, Simon and Ener, Semih and Sepehri-Amin, Hossein and Leineweber, Andreas and Gregori, Giuliano and Qu, Fei and Muralidhar, Shreyas and Ohkubo, Tadakatsu and Hono, Kazuhiro and Gutfleisch, Oliver and Kronmüller, Helmut and Schütz, Gisela and Goering, Eberhard
Title: On the synthesis and microstructure analysis of high performance MnBi
Language: English
Abstract:

Highly anisotropic MnBi powder with over 90 wt% low-temperature phase can be prepared using conventional arc-melting and 2 hour-low energy ball milling (BM) followed by magnetic separation. After proper alignment, the purified Mn55Bi45(Mn45Bi55) powder show remarkable magnetic properties: mass remanence of 71(65) Am2/kg and coercivity of 1.23(1.18) T at 300 K. The nominal maximum energy product of 120 kJ/m3 is achieved in the purified 2h-BM Mn55Bi45 powder, close to theoretical value of 140.8 kJ/m3. The Mn55Bi45(Mn45Bi55) bulk magnets show the highest volume remanence of 0.68(0.57) T at 300 K, while they were consolidated at 573(523) K by a pressure of 200 MPa for 5 minutes using hot-compaction method. In addition to the observed grain size, the coercivity of the hot-compacted samples at 300 K was found to be strongly related to the amount of metallic Mn and Bi residue at the grain-boundary. Our study proves that the magnetic properties of the Mn45Bi55 bulk magnets are stable up to 500 K, and the nominal (BH)max values are still above 40 kJ/m3 at 500 K showing the potential ability for high-temperature applications.

Journal or Publication Title: AIP Advances
Volume: 6
Number: 12
Publisher: AIP Publishing
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Functional Materials
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 17 Jan 2017 12:49
Official URL: http://dx.doi.org/10.1063/1.4971759
Identification Number: doi:10.1063/1.4971759
Funders: The authors gratefully acknowledge the support of the Deutsche Forschungsgemeinschaft for the project HPPMSNG and German federal state of Hessen for the program LOEWE RESPONSE, respectively.
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