Chapter 1 Introduction

1.1 Rare EarthPermanent-magnetAlloys

1.1.1 Rare earth

1.1.2 Classification and development of rare earth permanent-magnet alloys

1.1.3 Crystal structure of rare earth permanent-magnet alloys

1.1.4 Magnetic parameters of rare earth permanent-magnet alloys

1.1.5 Criterion of permanent-magnet alloys(materials)

1.2 Principle for Alloy Phase and Phase Transformation and Growth Rule of New Phase

1.2.1 Phase

1.2.2 Phase transformation

1.2.3 Alloy

1.2.4 Material

1.2.5 Alloy phase

1.2.6 Solid solution

1.2.7 Exsolution precipitation

1.2.8 Thermodynamic bases for phase transformation and classification

1.2.9 Single crystal

1.2.10 Single crystal superalloy

1.2.11 Enthalpy

1.2.12 Entropy

1.2.13 Latent heat of phase transformation

1.2.14 Driving force of phase transformation

1.2.15 Rule of growing up of new phase

1.3 Research Methods of the Magnetic Properties of Rare Earth Permanent Magnets

Reterences

Chapter 2 The First Generation Rare Earth Permanent-magnet Alloys

2.1 High temperature Phase Transition and Magnetic Properties of SmCo5 Permanent-magnet Alloys

2.2 The in Situ and Dynamic Observation on High Temperature Phase Transformation of SmCo5 Permanent Magnetic Alloyat 25-750℃

2.2.1 Magnetic measurement

2.2.2 Sample preparation and experiment method

2.2.3 Influence of annealing treated specimen on coercivity

2.2.4 The in situ and dynamic observation by 1000kV HVEM under heating condition

2.2.5 Discussion

2.3 Magnetism and the in Situ and Dynamic Observation of Permanent MagneticAlloy of SmCo5 byAnnealing at 600-1000℃

2.3.1 Specimen preparation and experimental method

2.3.2 Analysis on chemical composition of the SmCo5 permanent magnetic alloy

2.3.3 Magnetic measurement

2.3.4 Structure of magnetic domain

2.3.5 Irreversible loss of SmCo5 permanent magnetic alloy after annealing at 25-1000℃

2.3.6 Electronic energy spectrum experiment and analysis of SmCos permanent magnetic alloy

2.3.7 The in situ and dynamic observation on eutectoid decomposition of SmCo5 by electronic microscope

2.3.8 The in situ and dynamic observation of SmCo5 in thermal state using transmission electronic microscope

2.3.9 The in situ and dynamic observation on SmCo5 in thermal condition of 750-960℃ by Transmission Electronic Microscope

2.3.10 Discussion

2.3.11 Conclusions

2.4 Analysis on Variation ofthe Coercivity and Phase Transformation

2.4.1 Specimen preparation and experimental method

2.4.2 Experimental result and discussion

2.4.3 Conclusions

2.5 The Optic-electronic Spectrum Study on SmCo5 Permanent MagneticAlloy

2.5.1 Specimen preparation technique and experimental condition of optic-electronic energy spectrum

2.5.2 Investigation on surface composition of SmCo5

2.5.3 Atoms concentration variation of elements of samarium,cobalt and oxygen from surface to depth

2.5.4 Surface compound

2.5.5 Conclusions

2.6 Analysis on Magnetic Hysteresis Loop of SmCo5 Permanent MagneticAlloy

2.6.1 Specimen preparation technique,magnetic measurement and transmission microscope condition and experimental method

2.6.2 Analysis on chemical composition of three kinds of specimens

2.6.3 Analysis on preparation technique

2.6 4 Curve of magnetic performance and analysis at 77-550K

2.6.5 Observation and analysis on specimen using TEM

2.6.6 Conclusions

2.7 Magnetism of SmCo5 Permanent Alloy at 1.5-523K

2.7.1 Specimen preparation technique,magnetic measurement apparatus and experimental method

2.7.2 Magnetism measurement and curve of SmCo5 permanent magnetic alloy at 1.5K and 40K

2.7.3 Measurement of demagnetization curve and value of magnetic parameter at-196-250℃ by magnetic parameter measurement apparatus

2.7.4 Reversible temperature coefficient of SmCo5 at-196-250℃

2.7.5 Coercivity of SmCo5 at 475-1000℃

2.7.6 Discussion

2.7.7 Conclusions

References

Chapter 3 The Second Generation Rare Earth Permanent-magnet Alloys

3.1 Phase Precipitation,Phase Transformation at High Temperature and Magnetism of High Coercivity Sm(Co,Cu,Fe,Zr)7.4

3.1.1 Specimen preparation process and experimental method

3.1.2 Results of specimen magnetic measurement

3.1.3 Microtexture of the alloy at room temperature

3.1.4 The in situ and dynamic observation on precipitation,growth up and high temperature phase transformation of cellular structure from room temperature to high temperature

3.1.5 Conclusions

3.2 Function of Zirconium on Sm(Co,Cu,Fe,Zr)7.4 Permanent Magnetic Alloy＆Observation and Analysis by Electron Microscope

3.2.1 Specimen preparation and experimental method

3.2.2 Research on function of Zirconium

3.2.3 Conclusions

3.3 Magnetism of High Coercivity Sm(Co,Cu,Fe,M)7 4Permanent Magnetic Alloy at 1.5-523K

3.3.1 Preparation of specimen and magnetism measurement apparatusz and measurement method

3.3.2 Measurement results and discussion

3.3.3 Conclusions

References

Chapter 4 The Third Generation Rare Earth Permanent Magnet

4.1 Improvement of the Properties of NdFeB Permanent Magnets Due to Element Substitutions

4.2 Magnetic Properties and the Occupancy of Co and Ga Atoms for NdFe(Co,Al,Ga)B Permanent-Magnetic Alloys

4.2.1 Preparation and method

4.2.2 Nd16Fe77-xCoxB7 alloy

4.2.3 Nd16Co10Fe67-yAlyB7 and Nd16Co16Fe61-yAlyB7 alloys

4.2.4 Nd16Co16Fe61-xGaxB7 alloy

4.2.5 Conclusions

4.3 The Studies of Main Phase Nd2Fe14B and Nd2(Fe,Co)14B in NdFeB Permanent-magnet Alloys

4.3.1 The preparation of samples and experimental methods

4.3.2 SEM analysis

4.3.3 The formation of Nd2Fe14B

4.3.4 M？ssbauer spectra at room temperature

4.3.5 Composition analysis and the studies of M？ssbauer spectra for Nd2(Fe,Co)14B

4.3.6 In situ and dynamic observation of TEM on Nd2Fe14B and Nd2(Fe,Co)14B

4.3.7 Conclusions

4.4 Studies on B-rich Phase in NdFeB Alloy

4.4.1 Preparation process and experimental method

4.4.2 The in situ and dynamic observation of Nd1.11Fe4B4 by TEM

4.4.3 Study on Nd1+εFe4B4 by X-Ray diffraction and M？ssbauer effect

4.4.4 Analysis on Nd1.1Fe4B4 phase

4.4.5 Relationship between B-rich phase and coercivity

4.4.6 Conclusions

4.5 Influence ofBoron Content in NdFeB on Nd2Fe14B Phase and Magnetic Property

4.5.1 Specimen preparation process and experimental method

4.5.2 Influence of boron content on alloy magnetic property and phase structure

4.5.3 Conclusions

4.6 High Curie Temperature NdFeCoGaB Permanent Magnetic Alloy

4.6.1 Preparation process and experiment method

4.6.2 Using cobalt to replace part of iron

4.6.3 Use Ga to replace part of iron in NdFeCoB alloy

4.6.4 Conclusions

4.7 Influence of Adding Element Dysprosium on Performance of NdFeB Alloy

4.7.1 Specimen preparation process and experimental method

4.7.2 Experiment result using SEM

4.7.3 Measurement of magnetism

4.7.4 Experiment result using transmission microscope

4.7.5 Distribution of Dy2O3

4.7.6 Conclusions

4.8 Nanocrystalline Microstructure and Coercivity Mechanism Model of NdFeB Alloys with Nb and Ga

4.8.1 Experimental procedure

4.8.2 Magnetic properties measuring

4.8.3 Study of M？ssbauer effect

4.8.4 Study of nano-microstructure of NdFeB alloys with Nb

4.8.5 Dynamic cross and microstructure of the NdFeB alloys with Nb and Dy

4.8.6 Dynamic cross and microstructure of the NdFeB alloys with Nb,Ga,Co and Dy

4.8.7 Curie temperature of the NdFeB alloys with Nb

4.8.8 New coercivity mechanism model of multi-component NdFeB alloys

4.8.9 Conclusions

4.9 In Situ and Dynamic Observation on Magnetic and Phase Transformation of Nd15Fe78B7 Permanent Magnet at High Temperature

4.9.1 Preparation process of specimen and experiment method

4.9.2 Microstructure and phase in crystal boundary of NdFeB permanent magnet

4.9.3 Phase transformation of microstructure of B-rich phase at high temperature

4.9.4 Phase transformation of microstructure of Nd-rich filmy belt in Nd15Fe78B7 crystal boundary at high temperature

4.9.5 Phase transformation of Nd2Fe14B base phase of Nd15Fe78B7 alloy at high temperature

4.9.6 Conclusions

4.10 In Situ and Dynamic Observation on High Temperature Phase Transformation and Magnetism of Nd16Fe77B7 Permanent Magnetic Alloy

4.10.1 Samples preparationprocess and experimental method

4.10.2 The in situ and dynamic observation on nanometer microstructure and high temperature phase transformation

4.10.3 Function of cobalt in NdFeCoB alloy

4.10.4 Magnetic characteristic measurement result and analysis

4.10.5 Curie temperature measurement result

4.10.6 Phase analysis by X-ray diffraction,lattice constant and cell volume

4.10.7 Relationship between aging temperature and coercivity of Nd16Fe69Co8B7

4.10.8 Conclusions

4.11 Analysis on Lamella Phase of Grain Boundary in Microstructure of NdFeB Permanent Magnetic Alloy

4.11.1 Experimental method

4.11.2 Magnetism measurement

4.11.3 Analysis on result of the in situ and dynamic observation of samples

4.12 Quick Quenched NdFeB Permanent Magnetic Alloy

4.12.1 Sample preparation technique and experimental method

4.12.2 Measurement result of quick quenched magnet

4.12.3 Relationship between crystallization temperature and coercivity

4.12.4 Microstructure at room temperature

4.12.5 The in situ and dynamic observation on the non-crystal sample transferring to micro-crystal by HVEM

4.12.6 Conclusions

4.13 Stability of the Rare Earth Permanent Magnetic Alloy

4.13.1 Stability on temperature

4.13.2 Time stability

4.13.3 Chemical stability

4.13.4 Conclusions

References

Chapter 5 Developments and Prospect of the Rare Earth Permanent-magnet Alloys

5.1 Overseas General Development

5.2 Domestic General Development

5.3 Development Survey of Preparation Technology

5.4 Application and Expectation

References

Appendix

Appendix 1 The Structure of Outer Electrons for Rare Earths

Appendix 2 Atomic and Ionic Radius of Rare Earths

Appendix 3 Physical Properties of Rare Earths

Appendix 4 Fundamental Physical Constants

Appendix 5 Conversion of magnetic quantity between SI and Gaussian units

Index