Nanostructured Rare-Earth

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Nanostructured Rare-Earth Transition-Metal
Permanent Magnets
Paul McGuiness
Department for Nanostructured Materials Jožef
Stefan Institute, Ljubljana, Slovenia
Womeninnano winter school february 7-9 2008
kranjska gora slovenia
2
Introduction

• Permanent-magnet (PM) materials
• Magnetic properties
• PM applications
• Nano melt-spun magnets
• Nano HDDR magnets
• Summary

H2
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Magnetic properties
Permanent-magnet properties
Ms
Br
BH max
Hci
Hcb
H
-H
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280 years of progress
lodestone (1724)
neodymium iron boron (2006)
ferrite (1950)
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Improved properties over time
50 MGOe
NdFeB
Sm2Co17
price mechanical temperature history
Sm2Fe17N3
SmCo5
AlNiCo
steel
Ferrite
1900
1950
2000
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Improved properties over time
1.4
Sintered NdFeB
1.2
Bonded nano HDDR NdFeB
Alnicos
1.0
0.8
Bonded SmCo
Br (Tesla)
0.6
0.4
(Bonded nano MQ NdFeB)
Sintered Ferrite
0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Hcj (MA/m)
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Automotive apps
2008 Lexus RX Hybrid
1118 magnets (inc. 2.9kg of Nd-Fe-B)
1998 Toyota Celica GT has 543 magnets
1987 Yugo 45 (GV) has 9 magnets
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Computer apps
Fujitsu 300 GB 2.5" SATA Hard Disk Drive
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Other apps
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Who makes RE-TM magnets?
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Processing Nd15Fe77B8-type materials
Nd15Fe77B8 - the magnet
Nd15Fe77B8 - the cast alloy
50 micron
50 micron
NdFe4B4
Nd2Fe14B
Nd2Fe14B
Nd-rich
Nd-rich
Nd-rich phase MP 630C
Nd2Fe14B Ms 1.6 Tesla Ha 5 MA/m
Tc 320C
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Processing Nd15Fe77B8-type materials
HDDR process
Powder
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Processing Nd15Fe77B8-type by melt spinning
NdFeB alloy
Melt spinner
600 deg C
crystalline ribbons
Over-quenched amorphous ribbons
die-upset magnet (aniso)
bonded magnet (iso)
hot-pressed magnet (iso)
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Processing Nd15Fe77B8-type by melt spinning
Die upset (fully dense anisotropic)
Hot pressed (fully dense isotropic)
Injection moulded (not fully dense isotropic)
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Processing Nd15Fe77B8-type by melt spinning
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Processing Nd15Fe77B8-type by HDDR process
Nd-rich
Nd-hydride
NdH2 Fe Fe2B
H2
Nd2Fe14B
750 degC
Isotropic and anisotropic forms are possible with
small additions of Zr and Ga
vac
Nd2Fe14B
650 degC
Womeninnano winter school february 7-9 2008
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Processing Nd15Fe77B8-type by HDDR process
10 microns
Anisotropic structure that can be aligned to
produce anisotropic bonded magnets
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Properties of NdFeB magnets
aniso melt-spun die upset
anisotropic sintered
1 T
iso HDDR bonded
iso melt-spun hot pressed
magnetisation
iso melt-spun injec mould
iso HDDR injec mould
coercivity
1000 kA/m
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Summary

• RE-TM magnets have a wide range of applications
• Properties depend on materials and processing
• A nano grain size and good microstructure is
  vital for good properties
• Good properties can be achieved with a range of
  techniques

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