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