This book encompasses the science, measurement, fabrica­ tion, and use of superconducting materials in large scale and small scale technologies. The present book is in some sense a continuation and completion of a series of two earlier books based on NA TO Advanced Study Institutes held over the last decade. The first book in the series entitled Superconducting Machines ~nd Devices: Large Systems Appli­ cations edited by S. Foner and B. B. Schwartz (1974) represented a compilation of all the applications of superconducting technology. The second book entitled Superconductor Applications: Squids and Machines, edited by B. B. Schwartz and S. Foner (1977) reviewed small scale applications and up-dated the large scale applications of superconductiv­ ity at that time. These two books are both introductions and advanced reference volumes for almost all aspects of the applications of super­ conductivity. The growth of applied superconductivity has mushroomed in the decade of the 1970's. Technologies which were discussed in the beginning of the 1970's are now beyond the prototype stage. Materials development and performance in operating systems is the basis of the continued applications and economic viability of super­ conducting technology. In this book, a complete review of all materials technology is presented by leading authorities who were instrumental in the development of superconducting materials technology. The present book is based on the NATO Advanced Study vi PREFACE Institute entitled Superconducting Materials: Science and Technology which was held from August 20 to August 30, 1980 in Sintra, Portugal.

1 Overview of Superconducting Materials Development.- I. Introduction.- II. Superconducting Materials of the First Kind.- A. Discovery.- B. Magnetic Properties.- C. Flux Penetration.- D. Nature of the Superconducting Transition.- 1. Bulk phase transition.- 2. Thin film phase transition.- E. The Two Fluid Model.- F. The Microscopic Theory.- III. Superconducting Alloys and Compounds, Early Work.- A. Introduction.- B. Critical Temperature Behavior.- C. Magnetic Field Behavior.- IV. Raising Tc With New Materials.- A. Introduction.- B. Transition Metal Alloys.- C. Carbides and Nitrides.- D. A15 Compounds.- 1. Progress in raising Tc.- 2. Present Tc situation.- 3. Factors depressing Tc.- 4. Other features of A15 behavior.- V. Superconductors of the Second Kind.- A. Introduction.- B. Another Kind of Superconductor.- C. Type II Materials.- VI. Unusual Materials and Future Possibilities.- A. Introduction.- B. Intercalation Compounds.- C. Organic Superconductors.- D. Low Carrier Density Superconductors.- E. Magnetic Superconductors.- F. Future Possibilities.- 2 Practical Superconducting Materials.- I. Introduction.- A. Practical Applications of Superconducting Materials.- B. Superconducting Materials in Common Use.- C. Problems in the Utilization of Superconducting Materials.- II. Stability: the General Problem.- A. Degradation and Training.- B. The Disturbance Spectrum.- C. Mechanical Sources of Disturbance.- D. Distributed Disturbances.- E. Point Disturbances.- F. Composite Conductors.- III. Flux Jumping.- A. General.- B. Screening Currents and the Critical State Model.- C. Adiabatic Theory of Flux Jumping.- D. Filamentary Composites.- E. Dynamic Stability.- F. Dynamic Stability with Finite Superconductor Thickness.- IV. C0ryogenic Stabilization.- A. Size Effects.- B. Principles of Cryogenic Stabilization.- C. Boiling Heat Transfer.- D. Resistivity of the Normal Metal.- E. Heat Conduction Effects.- F. Effect of Finite Superconductor Size.- G. Forced Flow Cooling.- H. Superfluid Helium.- I. Cryogenic Stabilization in Practice.- V. AC Losses.- A. The Fundamental Loss Mechanism.- B. Hysteresis Loss.- C. Hysteresis Loss with Transport Current.- D. Filamentary Composites.- E. Self-Field Losses in Filamentary Composites.- F. Longitudinal Field Effects.- G. Combined Losses.- VI. Quenching and Protection.- A. The General Problem.- B. Temperature Rise.- C. Voltage.- D. Self-Protecting Magnets.- E. Other Protection Techniques.- VII. Measurement Techniques.- A. General.- B. Measurement of Critical Transport Current.- C. Measurement of Magnetization.- D. Measurement at Different Temperatures.- 3 Niobium-Titanium Superconducting Materials.- I. Introduction.- II. Metallurgical and Structural Properties.- A. Phases of the Niobium-Titanium System.- B. Cold-Worked Microstructures.- C. Elastic and Plastic Mechanical Behavior.- D. Metallurgical Properties of Related Systems.- III. Physical Properties.- IV. Superconducting Properties.- A. Basic Properties.- 1. Transition temperature and upper critical field.- 2. Paramagnetic limitation and spin-orbit scattering.- 3. Nb-Ti base ternary and quaternary systems.- B. The Superconducting Critical Current Density.- 1. Measurement techniques.- 2. Critical current densities.- V. Industrial and Fabrication Considerations.- VI. Future Developments and New Directions.- A. Conventional Composites.- B. Unconventional Developments.- 4 Metallurgy of Continuous Filamentary A15 Superconductors.- I. Introduction.- II. History of the "Bronze Process".- A. Early History.- B. Evolution of the Process.- 1. The Ta diffusion barrier.- 2. The external diffusion process.- 3. The internal tin diffusion process.- 4. Bronze in Nb tubing.- 5. WRAP process.- 6. Other modifications.- III. Metallurgical Principles.- A. Thermodynamic Considerations.- B. Kinetics.- 1. Growth mechanisms.- 2. Experimental results.- IV. Influence of Metallurgical factors on Superconducting Properties.- A. Strains in Composite Superconductors and Their Influence on the Superconducting Properties.- B. Critical Temperatures.- 1. Effects of heat treatments.- 2. Effects of additives.- C. Critical-Current Densities and Magnetic Fields.- 1. Flux pinning (the scaling law).- 2. Temperature dependence.- 3. Grain size dependence.- 4. Effects of heat treatments and alloying.- 5. What is required for high Jc?.- V. Future Directions.- 5 Fabrication Technology of Superconducting Material.- I. Introduction.- II. Technology OF Solid Solution Superconductors.- A. Basic Properties of NbTi Alloys.- B. The influence of thermal treatment in the region of 873 K.- C. Mechanical Properties of NbTi Alloys.- D. Stress-Strain Behavior at Elevated Temperatures.- E. Raw Materials and Melting of NbTi.- F. Melting NbTi Alloys.- G. Sources of Inhomogeneities and Imperfections in the Molten Ingots.- H. Conductors and Fabrication Parameters.- I. Extrusion Technology.- 1. Extrusion billets and sealing techniques for single and multiextrusion.- 2. Extrusion presses and extrusion parameters.- 3. Extrusion temperature and preheating.- 4. Extrusion ram speed.- 5. Conductors containing mixed substrate.- J. Drawing Machinery, Twisting and Current Optimization.- K. Current Density Optimization and Properties of Monolithic Filamentary Conductors.- L. The Anisotropy of Rectangularly~Shaped Conductors.- M. Occurrence of the Ti Cu-Phase.- III. A15 Solid Solution Conductors.- A. Basic Properties of Nb3Sn and V Ga.- B. Principles of Solid State Diffusion.- C. Fabrication of the Conductors and Technology of High Sn-Content Bronzes.- D. Conductor Optimization with Respect to Layer Growth, Recrystalization, Kirkendall Effect,Filament Diameter and Filament Distribution.- E. Influence of Mechanical Strain on Electrical Properties.- F. Remarks About the Measurement of Critical Current Density of Technical Conductors.- G. Stabilization and Examples of Technical Conductors.- IV. Conductor Assembly By Braiding, Cabling, Mechanical Strengthening and Adding Stabilizers.- A. Technical Production of Flattened Cables and Braids.- B. Hollow Conductors and Fabrication Principles.- C. Fabrication of High Current, High Strength Hollow Conductors.- 1. Strands.- 2. Cr-Ni core with Kapton insulation.- 3. Cabling and Soldering.- 4. Strip for the conduit.- 5. Conductor completion.- V. Future Directions.- A. Sol…