醉染图书永磁体:历史与未来9787030644381

Preface

Chapter 1 Millenniums of Permanent Magnets: From Compasses to Rare-earth Magnets 1

References 5

Chapter 2 Coercivity Mechanisms in Nanostructured Permanent Magnets 7

2.1 Introduction 8

2.2 Hysteresis loops and a survey of various coercivity mechanisms 10

2.2.1 Hysteresis loops 10

2.2.2 Coherent rotation and domain wall motion 12

2.. Various modes of nucleation and nucleation expansion 14

2.2.4 Numerical approaches and more advanced models 16

. Interface-pinning of well-oriented permanent magnetic systems 18

..1 Basic formulation 18

..2 Comparison of nucleation and self-pinning fields 19

.. Experimental evidence and comparison with other theories 25

2.4 Discussions and conclusions 26

2.4.1 Single-phase versus two-phases 26

2.4.2 Pinning versus nucleation 27

2.4.3 Size e.ect and grain boundary enhancement 29

2.4.4 Conclusions 30

References 31

Chapter 3 Sm-Co High-Temperature Permanent Magnet Materials 36

3.1 Introduction 36

3.2 Historical review of development of Sm-Co permanent magnets 38

3.3 Phase diagram and crystal structures 40

3.4 Intrinsic magnetic properties of R-Co compounds 42

3.5 Sm-Co permanent magnets capable of oraig up to 300 46

3.6 High-temperature Sm2(Co， Fe， Cu， Zr)17-type magnets capable of oraig up to 550 51

3.6.1 Effects of coitions on high-temperature intrinsic coercivity of Sm-TM permanent magnets 52

3.6.2 New high-temperature Sm2(Co， Fe， Cu， Zr)17-type magnets 53

3.6.3 Long-term thermal stability of new high-temperature permanent magnets 56

3.6.4 Abnormal temperature dependence of intrinsic coercivity 57

3.7 Thermal stability， temperature coeffcien，ndmdeling of temperature-compensated magnets 57

3.7.1 Reversible and irreversible flux density loss 57

3.7.2 Temperature coeffcient 59

3.7.3 Modeling of temperature-compensated magnets 62

3.8 Nanograin structure， nanocrystalline， and nanocoite Sm-Co magnetic materials 65

3.9 Other Sm-Co permanent magnet materials 72

3.10 Prospects of future rare earth permanent magnet materials 73

3.11 Conclusions 76

References 77

Chapter 4 Ternary Fe-rich R-Fe-M Intermetallics with the ThMn12-type Structure and Their Interstitial Compounds 82

4.1 Introduction 82

4.2 Part one: Ternary Fe rich 1-12 compounds 85

4.2.1 Structural and magnetic properties of Y(Mn1.xFex)12 which is the first synthesis of Fe-rich 1-12 compounds 85

4.2.2 Structural and magnetic properties of RFe12.xMx 90

4.. Structural and magnetic properties of RTiFe11 in comparison with RTiC1 and YTi(Fe1.xNix)11 90

4.3 Part two: Interstitial nitrogen atom e.ect on the 1-12 compounds and its applications 108

4.3.1 Interstitial nitrogen atom e.ect on the 1-12 compounds 108

4.3.2 Interstitial hydrogen (or carbon) atom e.ect on the 1-12 compounds 116

4.3.3 Development of novel permanent magnets based on R(Fe，M)12Nx 121

4.4 Concluding remarks 129

References 130

Chapter 5 Mn-based Permanent Magnets 134

5.1 Introduction 135

5.2 Mn-Al hard magnetic phase 136

5.3 MnBi hard magnetic materials 147

5.4 MnxGa magnetic materials 157

5.5 Summary 164

References 164

Chapter 6 Anisotropic Nanocoite Soft/Har Mtlayer Magnets 169

6.1 Introduction 170

6.2 The anisotropic Nd2Fe14B based nanocoite multilayer magnets 171

6.3 Anisotropic SmCo5 based nanocoite permanent multilayer magnets 204

6.4 Anisotropic rare-earth free based nanocoite permanent multilayer magnets 211

References 218

Chapter 7 Nanocrystalline and Nanocoite Permanent Magnets by Melt Spinning Technique 2

7.1 Melt-spinning technique 224

7.2 Uniqueness in melt-spun materials 227

7.2.1 Cooling control 229

7.2.2 Amorphization and crystallization 2

7.. Phase formation 4

7.2.4 Consolidation

7.3 Melt-spun materials 241

7.3.1 Single-phase nanocrystalline magnets 241

7.3.2 Nanocoite magnets 266

7.3.3 Precipitation-hardening ribbons 288

7.4 Magnetic phenomena in melt-spun magnets 300

7.4.1 Single-phase magnetic behavior 301

7.4.2 Remanence enhancement 303

7.4.3 Henkel plot 306

7.4.4 Recoil loop 311

7.4.5 First-order reversal curve 317

7.4.6 Coercivity and microstructure parameters 320

7.4.7 Reversible and irreversible magnetization 3

7.5 Summary and outlook 325

References 326

Chapter 8 Grain Boundary Restructuring and La/Ce/Y Application in Nd-Fe-B Magnets 339

8.1 Introduction 340

8.2 Grain boundary restructuring of Nd-Fe-B sintered magnets 341

8.2.1 Fundamentals of grain boundary restructuring 341

8.2.2 (Pr， Nd)32:5Fe62:0Cu5:5 restructuring: High corrosion-resistant Nd-Fe-B 342

8.. Dy71:5Fe28:5 restructuring: High-coercivity Nd-Fe-B 350

8.3 Application of hi-aundant La/Y/Ce in Nd-Fe-B magnets 355

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