Scope and Purpose Although conductors based on the Al5 intermetallic compound Nb Sn 3 possess desirable high-field superconducting properties, manufacturing and handling difficulties, coupled with the tendency of their critical current densities to degrade rapidly under stress, have generally restricted their use to fairly straightforward, usually small-scale solenoidal-magnet applica­ tions. Likewise the Al5 compound VGa, which has a wider critical strain 3 window than NbSn but a uniformly lower upper critical field, has not 3 entered widespread service. Strain has been found to have no measurable influence on either the critical fields or the critical current densities of compound superconductors with BI and Cl5 crystal structures, but as yet they are still in the research and development stages. On the other hand, conductors using the binary alloy Ti-Nb or multi component alloys based on it, because of their relative ease of manufacture, excellent mechanical properties, and relatively low strain sensitivities, are now being pressed into service in numerous large-scale devices. Such conductors are being wound into magnets for use in energy storage, energy conversion (i. e. , generators and motors), and high-energy particle detectors and beam-handling magnets. of cold-rolled or drawn Ti-Nb-alloy wire for superconducting The use magnet applications was first proposed in 1961. During the ensuing ten years, while progress was being made in the development of Cu-clad filamentary-Ti-Nb-alloy conductors, Ti-Nb and other Ti-base binary transi­ tion-metal (TM) alloys were being employed as model systems in the fundamental study of type-II superconductivity.

Inhalt

I: Metallurgy.- 1. Equilibrium and Nonequilibrium Phases.- 1.1 Equilibrium Phases.- 1.1.1 Electron/Atom Ratio Systematics.- 1.1.2 Electronic Structure and Phase Stability.- 1.2 ?-Titanium Alloys.- 1.3 ?-Titanium Alloys.- 1.4 Binary Titanium-Transition-Metal Alloys.- 1.4.1 Further Classification Schemes for Titanium-Alloy Phases.- 1.4.2 The Ti-Cr System.- 1.4.3 The Ti-Nb System.- 1.5 Multicomponent Titanium-Transition-Metal Alloys.- 1.5.1 Titanium-Base Multicomponent Alloys in General.- 1.5.2 The Ti-Zr-Nb System.- 1.6 Nonequilibrium Phases.- 1.6.1 The Martensitic and Athermal ?-Phases in Quenched Titanium-Transition-Metal Alloys.- 1.6.2 The Quenching Process.- 1.6.3 Stability Limit of the ?-Phase in Titanium-Transition- Metal Alloys.- 1.7 Formation and Structures of the Martensitic Phases.- 1.7.1 Morphology of Martensites.- 1.7.2 Structure of the Martensites.- 1.7.3 Crystallographic, Thermodynamic, and Acoustic Aspects of the Martensitic Transformation.- 1.8 Occurrence and Structure of the Quenched w-Phase.- 1.9 Summary-The Occurrence of the Martensitic and co-Phases in Quenched Titanium-Niobium Alloys.- 2. Aging and Deformation.- 2.1 The Aging of Quenched ?-Titanium Alloys.- 2.2 The Athermal and Isothermal ?-Phases.- 2.2.1 Athermal ?-Phase.- 2.2.2 Isothermal ?-Phase.- 2.3 ?-Phase Separation.- 2.3.1 Occurrence of the Reaction.- 2.3.2 Ti-Cr.- 2.3.3 Ti-Mo.- 2.3.4 Ti-Nb.- 2.3.5 Thermodynamics of the Phase-Separation Reaction.- 2.4 ?-Phase Precipitation from ?-Titanium Alloys.- 2.4.1 Direct Precipitation.- 2.4.2 Precipitation from the ?' + ?-Phase.- 2.4.3 Precipitation from the ? + ?-Phase.- 2.5 Down-Quenching and Up-Quenching-?-Reversion.- 2.6 Effects of Third Element Additions on Precipitation in Quenched-and-Aged Titanium-Transition-Metal Alloys.- 2.6.1 The Ternary ? + ?Phase Regime.- 2.6.2 The Ternary ?' + ?-Phase Regime.- 2.7 ?-Phase Immiscibility.- 2.8 Effects of Cold Deformation on the Microstructures of Quenched ?-Titanium Alloys.- 2.8.1 Low- and High-Level Deformation Microstructures.- 2.8.2 Further Studies of Cold Rolling.- 2.8.3 Swaging.- 2.8.4 Flattening.- 2.8.5 Wire Drawing.- 2.8.6 Summary.- 2.9 Influence of Stress, Strain, and Interstitial-Element Additions on the Transformation Kinetics of Quenched ?-Titanium Alloys.- 2.10 Influence of Stress on the Transformation.- 2.11 Influence of Heavy Plastic Deformation.- 2.11.1 Influence of Heavy Deformation on the Kinetics of Precipitation.- 2.11.2 Influence of Aging on the Fibrous Cell Structure.- 2.12 The Influence of Interstitial-Element Additions.- 2.13 Summary-The Occurrence of Isothermal ?- and Equilibrium ?-Phases in Deformed and/or Aged Titanium-Niobium Alloys.- 2.13.1 The Isothermal ?-Phase.- 2.13.2 The Equilibrium ?-Phase.- 3. Mechanical Properties.- 1. HARDNESS.- 3.1 The Hardness Test.- 3.2 Hardness of Quenched Titanium-Transition-Metal Alloys.- 3.3 Hardness of Aged Titanium-Niobium Alloys.- 3.4 Influence of Third-Element Additions on the Hardnesses of Unalloyed Titanium and Titanium-Niobium Alloys.- 3.5 Hardness of Ternary and Quaternary Transition-Metal Alloys.- 3.6 Theoretical Relationships Between Hardness and Strength.- 3.7 Application of the Marsh formula to the Determination of the Yield Strength of a Wire.- 3.8 Normal and Anomalous Tensile Properties of Superconductors.- 2. ANOMALOUS MECHANICAL PROPERTIES.- 3.9 Anomalous Tensile and Related Properties.- 3.10 Acoustic Emission from Copper and Titanium-Niobium.- 3.11 Mechanical Fatigue of Composite Conductors.- 3.12 Thermomechanical Heating.- 3. NORMAL MECHANICAL PROPERTIES OF TITANIUM-NIOBIUM ALLOYS AND COMPOSITE CONDUCTORS.- 3.13 Young's Modulus of Titanium-Niobium Superconductors.- 3.14 Hardness and Modulus of Titanium-Niobium Superconductors.- 3.15 Hardness, Modulus, and Yield Strength in Titanium-Niobium Superconductors.- 3.16 Tensile Strengths of Titanium-Alloy Superconductors.- 3.17 Tensile Properties of Titanium-Niobium Technical Superconducting Alloys.- 3.18 Strengths of Titanium-Niobium-Base Multicomponent Alloys.- 3.19 Modulus and Strength of Composite Superconductors.- 3.20 Determination of the Tensile Properties of Composites.- 3.21 Strengthening Principles in Alloys and Composite Conductors.- 3.22 Strengthening of Alloys.- 3.23 Strengthening of Composite Conductors.- 3.24 Workability of Titanium-Alloy Superconductors.- II: Physics.- 4. Dynamic Elastic Modulus.- 4.1 Determination of Dynamic Moduli.- 4.1.1 Definitions and Interrelationships.- 4.1.2 Terminology.- 4.1.3 Long-Wavelength Measurement Techniques.- 4.2 Ultrasonic (MHz) Methods in Elastic Modulus Measurement.- 4.2.1 Cubic Monocrystals.- 4.2.2 The Isotropic Solid.- 4.2.3 The Anisotropic Solid.- 4.3 Calculation of Polycrystalline Elastic Moduli from the Mono- crystalline Compliance Moduli and Stiffness Moduli (i.e., the Elastic Constants).- 4.3.1 The VRH Approximation.- 4.3.2 The VRHG Approximation-The Debye Temperature.- 4.4 The Elastic Moduli of Titanium-Transition-Metal Alloys.- 4.5 Systematic Variation of Elastic Moduli with Composition and Microstructure in Titanium-Transition-Metal Alloys.- 4.5.1 The ?-Isomorphous Alloys Ti-V, Ti-Nb, and Ti-Mo.- 4.5.2 The ?-Eutectoid Alloys: Ti-Cr, Ti-Mn, Ti-Fe, Ti-Co, and Ti-Ni.- 4.6 The Dynamic Modulus of Titanium-Niobium.- 4.7 The Dynamic Moduli of Composite Superconductors.- 5. Electrical Resistivity.- 5.1 Electrical Resistivity of Titanium-Alloy Superconductors.- 5.2 Resistometrically Monitored Transformation and Aging.- 5.3 The Resistivity of Alloys-Composition Dependence.- 5.3.1 Simple Models of Alloy Resistivity.- 5.3.2 Residual Resistivities of Binary Transition-Metal Alloys.- 5.3.3 Relative Scattering Strengths of Simple-Metal and Transition-Metal Solutes in Ti.- 5.4 The Resistivity of Alloys-Temperature Dependence.- 5.4.1 Dilute Alloys at Low Temperatures.- 5.4.2 Ti-Alloy Resistivity at Moderate-to-High Temperatures.- 5.4.3 Ti-Alloy Resistivity at Moderate to Low Temperatures- Gross Features.- 5.5 Anomalous Resistivity Concentration Dependence and Temperature Dependence in Titanium-Base Alloys.- 5.5.1 Anomalous Concentration Dependence.- 5.5.2 Negative Temperature Dependence.- 5.6 Three Case Studies of Negative dp/dT.- 5.6.1 Negative dp/dT in Ti-V and Ti-Mo.- 5.6.2 Negative dp/dT in Ti-Cr.- 5.7 Mechanisms of Anomalous Resistivity Temperature D…