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Effects of Quenching Environment on the Structure of Melt- Spun Nd2Fe14B

Published online by Cambridge University Press:  21 February 2011

M. J. Kramer ,
Yali Tang ,
K.W. Dennis  and
R. W. Mccallum
M. J. Kramer
Affiliation:
Ames Laboratory, Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020 Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020
Yali Tang
Affiliation:
Ames Laboratory, Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020
K.W. Dennis
Affiliation:
Ames Laboratory, Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020
R. W. Mccallum
Affiliation:
Ames Laboratory, Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020 Department of Materials Science and Engineering, Iowa State University, Ames, IA 50011-3020
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Abstract

Melt-spun Nd2Fe14B (2–14–1) ribbons were produced under active vacuum and different partial pressures of inert gases of Ar and He. Microstructure and thermal analyses were performed to understand the microstructural evolution and glass formability (GF) of the ribbons. He atmosphere enhances the quenchability of the ribbons over Ar and vacuum. Ribbons made under 250 Torr He have more uniform microstructure and smoother surfaces than those under 760 Torr He. The higher quenchability induced by He, which increases the interfacial heat transfer coefficient between the melt and rotating wheel during melt spinning, is due to its higher thermal conductivity compared to Ar. The lower pressure stabilizes the turbulence between the melt-pool and Cu wheel, enhancing the heat transfer resulting in a more uniform quench. As a result, a more uniform ribbon microstructure can be obtained at relatively low wheel speeds.

Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 577: Symposium H – Advanced Hard and Soft Magnetic Materials , 1999 , 57
Copyright
Copyright © Materials Research Society 1999

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References

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