Nanostructured Rare-Earth Transition-Metal Permanent Magnets
Paul McGuiness
Department for Nanostructured MaterialsJožef Stefan Institute, Ljubljana, Slovenia
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
• Permanent-magnet (PM) materials
• Magnetic properties
• PM applications
• Nano melt-spun magnets
• Nano HDDR magnets
• Summary
H2
Introduction
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Magnetic properties
MsBr
Hci Hcb
BHmax
Permanent-magnet properties
+H-H
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
lodestone(1724)
ferrite(1950)
neodymiumiron boron(2006)
280 years of progress
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
1900 1950 2000
50 MGOe
steel
AlNiCo
Ferrite
SmCo5
Sm2Co17
Sm2Fe17N3
NdFeB
+ price+ mechanical+ temperature+ history
Improved properties over time
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Improved properties over time
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.00.2 0.4 0.6 0.8 1.0 1.2 1.4
Br (Tesla)
Hcj (MA/m)
Sintered NdFeB
Bonded SmCo
(Bonded nano MQ NdFeB)Sintered Ferrite
AlnicosBonded nano HDDR NdFeB
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
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
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Computer apps
Fujitsu 300 GB 2.5" SATA Hard Disk Drive
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Other apps
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Who makes RE-TM magnets?
1986
US24%
Europe25%
Japan41%
China10%
1996
US11% Europe
9%
Japan38%
China42%
2006 US0%
Europe2%
Japan20%
China78%
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Processing Nd15Fe77B8-type materials
NdFe4B4
Nd-rich
Nd2Fe14B
50 micron
Nd15Fe77B8 - the cast alloy
Nd2Fe14B Ms = 1.6 Tesla Ha = 5 MA/m Tc = 320°C
Nd-rich phase
MP = ~630°C
Nd15Fe77B8 - the magnet
50 micron
Nd2Fe14BNd-rich
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Sintered magnets
Vacuum sintering
Attritor milling
Melt spinning
Ribbons Powder
HDDR process
Casting
Processing Nd15Fe77B8-type materials
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Processing Nd15Fe77B8-type by melt spinning
Melt spinner
Over-quenchedamorphous ribbons
NdFeB alloy
crystallineribbons
bonded magnet(iso)
hot-pressed magnet(iso)
die-upset magnet(aniso)
~600 deg C
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Processing Nd15Fe77B8-type by melt spinning
Injection moulded(not fully denseisotropic)
Hot pressed(fully denseisotropic)
Die upset(fully denseanisotropic)
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Processing Nd15Fe77B8-type by melt spinning
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Processing Nd15Fe77B8-type by HDDR process
750 degC
H2
vac
650 degC
Nd2Fe14B NdH2
+ Fe
+Fe2B
Nd2Fe14BIsotropic andanisotropic formsare possible with small additions of Zr and Ga
Nd-rich Nd-hydride
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
Processing Nd15Fe77B8-type by HDDR process
10 microns
Anisotropic structure that canbe aligned to produce anisotropic bonded magnets
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
coercivity
magnetisation
1000 kA/m
1 T
anisotropic sintered
aniso melt-spun die upset
iso melt-spun hot pressed
iso melt-spun injec mould
iso HDDR injec mould
iso HDDR bonded
Properties of NdFeB magnets
Womeninnano winter schoolfebruary 7-9 2008 kranjska gora slovenia
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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