CONTENTS PART II. MAGNETIC PROPERTIES OF MATERIALS

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1 PART I. INTRODUCTION 1. CONCEPTS OF FERROMAGNETISM I Magnetic Field 1 Intensity of Magnetization and Magnetic Induction 2 Magnetization and Permeability Curves 3 Hysteresis Loop 4 Ferromagnetism, Paramagnetism and Diamagnetism 5 Kinds of Permeability 6 Saturation 7 Ideal Magnetization 8 Demagnetization Curve 8 Demagnetizing Field, Air Gaps 9 Magnetostriction 11 Magnetic Anisotropy 11 Spontaneous Magnetization FACTORS AFFECTING MAGNETIC QUALITY 14 Phase Diagram 15 Physical Factors 18 Production of Magnetic Materials 19 Melting and Casting 20 Fabrication 24 Heat-Treatment 28 Effect of Composition 29 Gross Chemical Composition 29 Impurities 35 Some Important Physical Properties 38 Properties Affected by Magnetization 46 PART II. MAGNETIC PROPERTIES OF MATERIALS 3. TECHNICAL AND PURE IRON 48 Manufacture of Iron and Steel 48 Chemical Composition 51 Preparation of Pure Iron 51 Physical Properties 53 Magnetic Properties of Commercial Material 55 Temperature 56 Heat Treatment of Ordinary Iron 58 ix

2 x Hydrogen Treatment 60 Removal of Impurities IRON-SILICON ALLOYS 67 History of Magnetic Alloys 67 Methods of Production 68 Phase Diagram 71 Physical Properties 74 Magnetic Saturation and Curie Point 76 Permeability and Losses of Hot-Rolled Sheet 79 Effect of Non-Metallic Impurities 83 Grain Size 86 Metallic Additions 87 Preferred Crystal Orientation 88 Properties at Low Inductions 92 Silicon Cast Iron 94 Structural Steels 95 Iron-Silicon-Aluminum Alloys IRON-NICKEL ALLOYS 102 Binary Iron-Nickel Alloys 102 Structure 102 Density, Lattice Parameter and Thermal Expansion 103 Resistivity 104 Elastic and Mechanical Properties 106 History of Magnetic Investigations 106 Magnetic Saturation Ill Preparation and Annealing of Alloys 112 Dependence of Induction on Field Strength 113 Permeability, Coercive Force and Hysteresis Loss 115 Annealing Temperature and Time 115 Heat Treatment in a Magnetic Field Heat Treatment in Hydrogen 121 Mechanical Treatment 124 Commercial Binary Alloys Permalloy Permalloy. Hipernik 129 Compressed Permalloy Powder 131 Isoperm 133 Permenorm 5000 Z 133 Thermoperm 133 Iron-Nickel-Molybdenum Alloys 134 Structure 134 Magnetic Properties 136 Commercial Alloys. Molybdenum Permalloy 139 Supermalloy 140 Compressed Molybdenum Permalloy Powder 144

3 xi Iron-Nickel-Chromium Alloys 146 Structure and Magnetic Properties 146 Commercial Alloys 152 Iron-Nickel-Copper Alloys 153 Structure and Physical Properties 153 Magnetic Properties 155 Commercial Alloys. Mumetal Alloy 160 Iron-Cobalt-Nickel Alloys 160 Structure and Physical Properties 161 Magnetic Properties 163 Heat Treatment in a Magnetic Field.171 Reversible Permeability 177 Commercial Alloys 179 Other Iron-Nickel Alloys 180 Iron-Nickel-Manganese Alloys 180 Iron-Nickel-Aluminum Alloys 183 Iron-Nickel-Silicon Alloys 184 Iron-Nickel Alloys Containing Ti, V, Ta or W 186 Alloys Containing Silver or Beryllium IRON-COBALT ALLOYS 190 Structure and Physical Properties 190 Magnetic Properties 193 Iron-Cobalt Alloys with Additions 199 Iron-Cobalt-Vanadium Alloys 200 Other Iron-Cobalt Alloys OTHER IRON ALLOYS OF HIGH PERMEABILITY 210 Iron-Aluminum Alloys 210 Iron-Antimony to Iron-Oxygen 220 Ferrites 244 Iron Alloyed with Palladium and Platinum Metals 249 Iron-Phosphorus to Iron-Zirconium OTHER HIGH PERMEABILITY MATERIALS 261 Cobalt 261 Metallurgy of Cobalt 261 Physical Properties 262 Magnetic Properties 264 Nickel 267 Metallurgy of Nickel 268 Physical Properties 269 Magnetic Properties 269

4 xii Cobalt-Nickel Alloys 276 Structure and Physical Properties 276 Magnetic Properties 278 Ternary Alloys 280 Other Cobalt Alloys 281 Cobalt-Aluminum to Cobalt-Zirconium 283 Other Nickel Alloys 299 Nickel-Aluminum to Nickel-Zirconium 299 Heusler Alloys 328 Structure 328 Saturation and Curie Point 330 Permeability and Hysteresis 333 Other Manganese Alloys 334 Manganese-Antimony to Manganese-Tin 334 Curie Points of Arsenic Group 341 Other Alloys and Elements 341 Chromium-Antimony to Chromium-Tellurium 341 Silver-Fluorine 342 Potassium-Sulfur 342 Gadolinium PERMANENT MAGNETS 344 Introduction 344 History 345 Energy Product 348 Demagnetization Curve 349 Reversible Permeability and Spring Back 353 Stability 354 Design of Permanent Magnets 359 Properties of Alloy Systems 364 Iron-Carbon Alloys. Constitution 364 Physical Properties 367 Magnetic Properties 367 Additions of Manganese 370 Tungsten Steels 371 Chrome Steels 374 Chrome-Tungsten Steels 378 Molybdenum Steel 378 Cobalt Steels 379 Other Steels 382 Iron-Cobalt-Molybdenum and Iron-Cobalt-Tungsten Alloys Iron-Nickel-Aluminum Alloys 385 Additions of Cobalt and Copper 388 Heat Treatment in Magnetic Field 389

5 xiii Alloys Containing Titanium 394 Iron-Nickel-Copper Alloys 396 Cobalt-Nickel-Copper Alloys 402 Iron-Cobalt-Vanadium Alloys 405 Alloys with Noble Metals. Iron-Platinum Iron-Palladium 411 Iron with Other Noble Metals 412 Cobalt-Platinum 412 Cobalt-Palladium 414 Nickel with Noble Metals 414 Chromium-Platinum 415 Manganese-Silver-Aluminum Alloys 415 Other Binary Alloys 416 Other Ternary and Complex Alloys 416 Powder Metallurgy 416 Magnets from Electrodeposited Powder 417 Powder Magnets 419 Oxide Magnets 421 PART III. MAGNETIC PHENOMENA AND THEORIES 10. MAGNETIC THEORY 423 Ferromagnetism 423 Ewing's Theory 423 Limitations of Ewing's Theory 425 The Weiss Theory 427 Quantum Theory 430 Ferromagnetics Above the Curie Point 432 Molecular Field Constant, N 433 Atomic Structure of Ferromagnetic Materials 434 Collective Electron Ferromagnetism 442 Interpretation of the Molecular Field 443 Thermal Expansion Near T = T 3^Law 448 Gyromagnetic Effect 449 Gyromagnetic Experiments 451 Experimental Values of g 453 Diamagnetism 455 Theory of Diamagnetism 458 Simple Salts and Their Solutions 459 Other Compounds 460 Paramagnetism 461 Rare Earths 463 Ions of the Iron Group 464 Paramagnetism at Low Temperatures 465 Paramagnetic Gases 466 Paramagnetism of Free Electrons 467

6 xiv Molecular Beams 468 Nuclear Moments 468 Antiferromagnetism THE MAGNETIZATION CURVE AND THE DOMAIN THEORY 476 Three Parts of Magnetization Curve 476 General Description of Domain Theory 477 Stability of Domain Orientation 481 Approach to Saturation 484 Initial Portion of Curve 489 Experimental Test of Rayleigh's Law 492 Rectangular Hysteresis Loops 494 Constricted Loops 498 Coercive Force and Residual Induction 499 Interpretation of Retentivity by Domain Theory 501 Hysteresis 507 Rotational Hysteresis 514 Distribution of Heat-Loss Over Magnetic Cycle 518 Barkhausen Effect 524 Powder Patterns 532 Incremental and Reversible Permeability 53S Reversible Permeability vs Induction 543 Incremental Permeability vs Amplitude 546 Hysteresis with Superposed Fields 549 Superposed Non-Parallel Fields MAGNETIC PROPERTIES OF CRYSTALS 555 Permeability 558 Remanence and Coercive Force 561 Crystal Anisotropy Energy 563 Torque Curves 565 Values of Constants 567 Calculation of Magnetization Curves 576 Calculation of Torque Curves 584 Anisotropy in Polycrystalline Sheet 586 Rotational Hysteresis 590 Origin of Anistropy STRESS AND MAGNETOSTRICTION 595 Stress 595 Strain Beyond Elastic Limit 596 Stress Within the Elastic Limit 600 Domain Theory of Effect of Stress 610 Effect of Very Small Stresses 613 Internal Strains 619 Magnetostriction 627 Experimental Methods 628 Brief Survey 630

7 xv Domain Theory 634 Preferred Domain Orientations 636 Reversible Magnetostriction 639 Volume Magnetostriction 641 Magnetostriction of Single Crystals 645 Theory of Saturation in Single Crystals 649 Magnetostriction in Unsaturated Crystals 652 Origin of Magnetostriction 654 Magnetostriction Data 655 Iron 655 Cobalt 657 Nickel 659 Iron-Cobalt Alloys 663 Iron-Nickel Alloys 664 Cobalt-Nickel Alloys 672 Other Iron-Cobalt-Nickel Alloys 674 Other Iron Alloys 676 Other Soft Materials 680 Permanent Magnet Materials 682 Change of Elastic Modulus 684 Introduction 684 Experimental Methods 686 Some Experimental Results 687 Theory for Large Internal Strain 690 Small Internal Strains 692 Comparison with Data 693 Change of Near Curie Point 697 Other Data 699 Magnetomechanical Damping 699 Damping Constants 700 Damping in Some Materials 701 Macro Eddy Currents 703 Micro Eddy Currents 706 Magnetomechanical Hysteresis 707 Separation of Losses 709 Additional Data TEMPERATURE AND THE CURIE POINT 713 Effect of Phase Changes 715 Magnetization Near the Curie Point 716 Low Temperatures 719 Variation of Curie Point with Composition 720 Curie Point and Pressure 723 Changes in Properties Near Curie Point 728 Applications ENERGY, SPECIFIC HEAT, AND MAGNETOCALORIC EFFECT 729 Energy of Magnetization 729

8 xvi Thermodynamic Expressions 731 Application to Magnetostriction 732 Heat Capacity 732 Comparison with Experiment 734 Low Temperatures 738 Magnetocaloric Effect 740 Temperature Change and Torque MAGNETISM AND ELECTRICAL PROPERTIES 745 Resistivity and Field Strength (Magnetoresistance) 745 Effect of Tension 748 Quantitative Aspects of Domain Theory. Polycrystalline Material Results for Alloy Series 756 Effect of Temperature 760 Magnetoresistance in Single Crystals 764 Effect of Anisotropy of Magnetostriction 766 Effect of Phase Change CHANGE OF MAGNETIZATION WITH TIME 769 Effect of Eddy Currents 769 Eddy Currents in Sheets 770 Eddy Currents in Cylinders 775 Wire Carrying Current 776 Eddy Current Losses 778 Losses in Low Fields 780 Losses at Intermediate and High Inductions 781 Eddy Currents with Change in Field 783 Propagation of Magnetic Waves 788 Magnetic Lag (not due to eddy currents) 788 Lag Dependent on Impurities 789 Jordan Lag 796 Long Period Lag. Aging 797 Permeability at Very High Frequencies 798 Ferromagnetic Resonance 803 Experimental Values of g 808 Resonance in Single Crystals SPECIAL PROBLEMS IN DOMAIN THEORY 811 Kinds of Magnetic Energy 811 Introduction 811 Crystal Anistropy 811 Magnetic Strain Energy 812 Mutual Energy Between Magnetization and External Field Magnetostatic Energy 814 Energy of Bloch Wall 814 Evaluation of Wall Energy and Thickness 816 Magnetic Processes 818 Rotational Processes 818 Boundary Displacement 820

9 xvii Applications to Specific Problems 821 Initial Permeability 821 Coercive Force 823 Fine Particles 828 Domain Geometry 834 PART IV. MEASUREMENTS 19. MEASUREMENT OF MAGNETIC QUANTITIES. 838 Basic Relations 838 Field of a Magnet 838 Fields Produced by Currents 839 Force on Magnet in Field 841 Force on Current in Field 842 Electromotive Force and Magnetomotive Force 842 Common Methods 843 Ballistic Method with Ring 843 Rod Specimens. Demagnetizing Factors 845 Yokes and Permeameters 849 Alternating Current Methods 852 Special Methods 855 Production of High Fields 855 Magnetometers 857 Para- and Diamagnetic Materials 857 Liquids and Gases 859 Other Special Measurements 860 APPENDIX 1. SYMBOLS USED IN TEXT 862 APPENDIX 2. SOME PHYSICAL PROPERTIES OF THE ELEMENTS 864 APPENDIX 3. VALUES OF SOME CONSTANTS 867 APPENDIX 4. MAGNETIC PROPERTIES OF VARIOUS MATERIALS 868 BIBLIOGRAPHY 875 NAME INDEX 947 SUBJECT INDEX 959