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Title: Preparation of highly pure α-MnBi phase via melt-spinning

Abstract

High concentration of the magnetically hard α phase in the Mn-Bi alloys is important for the development of these alloys as rare-earth-free permanent magnets. Among several explored manufacturing methods, melt-spinning followed by annealing is known to be suitable of producing the most pure α structure. In this work, a series of melt-spun Mn 100-xBi x alloys was prepared with x = 43 – 51 at a wheel speed of 67 m/s by ejecting the alloys through orifices 0.17 mm and 0.27 mm in diameter. The smaller orifice diameter favored formation of an amorphous phase in the as-spun alloys as well as a higher saturation magnetization M s in the alloys subsequently annealed at 300 °C. Although the most pure, 98 vol.%, α phase was obtained for the off-stoichiometric Mn 55Bi 45 composition, the M s of this material was lowered, possibly because the excess Mn atoms induced antiferromagnetic coupling in the α phase. The highest M s of 78 emu/g was obtained for a composition closer to the Mn 50Bi 50 stoichiometry, despite the slightly lower purity of α phase. Furthermore, evolution of the room-temperature coercivity with the formation of the α phase in the melt-spun alloys was studied formore » the Mn 55Bi 45 ribbons compacted at 275 °C; the coercivity values of around 1 kOe obtained through this simple procedure are not sufficient for permanent magnet applications.« less

Authors:
ORCiD logo [1];  [1];  [2]
  1. Univ. of Delaware, Newark, DE (United States)
  2. Iowa State Univ., Ames, IA (United States)
Publication Date:
Research Org.:
National Energy Technology Laboratory, Pittsburgh, PA, and Morgantown, WV (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1499685
Grant/Contract Number:  
EE0007794
Resource Type:
Accepted Manuscript
Journal Name:
AIP Advances
Additional Journal Information:
Journal Volume: 8; Journal Issue: 5; Journal ID: ISSN 2158-3226
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE

Citation Formats

Gabay, A. M., Hadjipanayis, G. C., and Cui, J. Preparation of highly pure α-MnBi phase via melt-spinning. United States: N. p., 2017. Web. doi:10.1063/1.5006491.
Gabay, A. M., Hadjipanayis, G. C., & Cui, J. Preparation of highly pure α-MnBi phase via melt-spinning. United States. doi:10.1063/1.5006491.
Gabay, A. M., Hadjipanayis, G. C., and Cui, J. Wed . "Preparation of highly pure α-MnBi phase via melt-spinning". United States. doi:10.1063/1.5006491. https://www.osti.gov/servlets/purl/1499685.
@article{osti_1499685,
title = {Preparation of highly pure α-MnBi phase via melt-spinning},
author = {Gabay, A. M. and Hadjipanayis, G. C. and Cui, J.},
abstractNote = {High concentration of the magnetically hard α phase in the Mn-Bi alloys is important for the development of these alloys as rare-earth-free permanent magnets. Among several explored manufacturing methods, melt-spinning followed by annealing is known to be suitable of producing the most pure α structure. In this work, a series of melt-spun Mn100-xBix alloys was prepared with x = 43 – 51 at a wheel speed of 67 m/s by ejecting the alloys through orifices 0.17 mm and 0.27 mm in diameter. The smaller orifice diameter favored formation of an amorphous phase in the as-spun alloys as well as a higher saturation magnetization Ms in the alloys subsequently annealed at 300 °C. Although the most pure, 98 vol.%, α phase was obtained for the off-stoichiometric Mn55Bi45 composition, the Ms of this material was lowered, possibly because the excess Mn atoms induced antiferromagnetic coupling in the α phase. The highest Ms of 78 emu/g was obtained for a composition closer to the Mn50Bi50 stoichiometry, despite the slightly lower purity of α phase. Furthermore, evolution of the room-temperature coercivity with the formation of the α phase in the melt-spun alloys was studied for the Mn55Bi45 ribbons compacted at 275 °C; the coercivity values of around 1 kOe obtained through this simple procedure are not sufficient for permanent magnet applications.},
doi = {10.1063/1.5006491},
journal = {AIP Advances},
number = 5,
volume = 8,
place = {United States},
year = {2017},
month = {12}
}

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Cited by: 2 works
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