This chapter provides a view of magnetism in materials used at low temperatures. The discussion covers the concepts, definitions, and systems of units that are unique to the study of magnetic properties. The chapter provides a description of some of the techniques and devices used for determining magnetic properties.

This chapter discusses the advantages of using powder metallurgy to produce magnetic materials, particularly its ability to control chemistry and near-net shape. It also explains how process parameters and powder characteristics influence the physical and magnetic properties of common stainless steels.

The physical properties of a material are those properties that can be measured or characterized without the application of force and without changing material identity. This chapter discusses in detail the common physical properties of metals, namely density, electrical properties, thermal properties, magnetic properties, and optical properties. Some physical properties for a number of metals are given in a table.

This article discusses the compositions, structures, and properties of the most common grades of soft magnetic metals and permanent magnet alloys. It explains how alloying additions and impurities affect the magnetic properties of these materials, which include commercially pure and phosphorus irons, low-carbon and silicon steels, ferritic stainless steels, and nickel-iron and iron-cobalt alloys.

This chapter describes the physical properties of steels used for castings. The properties covered include density, modulus of elasticity, Poisson's ratio, shear modulus, thermal expansion, thermal conductivity, specific heat, thermal diffusivity, electrical resistivity, and magnetic properties.

This chapter discusses the basic principles of induction heating and related engineering considerations. It describes the design and operation of induction coils, the magnitude and distribution of magnetic fields, and the forces that generate eddy currents in metals. It explains how induced electrical current causes metal to heat in proportion to their electrical resistance and how it affects temperature dependent properties such as resistivity and specific heat and, in turn, heating rates and efficiencies. It also discusses the effect of hysteresis and explains why eddy currents tend to be confined to the outer surface of the workpiece, a phenomenon known as the skin effect. The chapter includes several data plots showing how the depth of heating varies with frequency and how heating time, power density, and thermal conduction rate correspond with hardening depth.

This article discusses the general purpose of alloying and identifies some of the material properties and behaviors that can be improved by adding various elements to the base metal. It explains how alloying can make metals stronger and more resistant to corrosion and wear as well as easier to cast, weld, form, and machine. It also discusses some of the alloying techniques that have been developed to address problems stemming from dissimilarities between the base metal and alloying or inoculate material.

This chapter discusses the use of phase diagrams in alloy design, processing, and performance assessment. The examples cover both ferrous and nonferrous metals and a variety of goals and objectives. The chapter also identifies limitations and pitfalls associated with the use of phase diagrams.

This chapter addresses some of the challenges involved in materials selection, providing context for much of the information presented in the book. It describes a typical four-step design scenario, noting material-related considerations and information needs. It explains how design decisions are complicated by the interconnected nature of material properties, design geometry, and manufacturing requirements and effects. The chapter also assesses the design impact of several materials and discusses codes, standards, and specifications.

Liquid penetrant, magnetic particle, and eddy current inspection are used to detect surface flaws. This chapter is a detailed account of the physical principles, process description, equipment requirements, selection criteria, advantages, limitations, and applications of these surface flaw detection techniques.

The chapter presents an overview of the properties and operational limits of superconductive materials, as well as techniques used to fabricate practical superconducting wires. It introduces six properties: critical temperature, critical magnetic field, critical current density, stability, ac loss, and mechanical characteristics; for each property, typical data are provided and the experimental methods used to measure it are briefly described. The properties of the superconducting composites are tied together in the chapter to summarize their effect on superconductor material selection and the geometrical design of superconducting composites. The chapter also contains a reference guide to composite-design factors with links to the relevant chapter sections where each design consideration is addressed.

Nonferrous metals are of commercial interest both as engineering materials and as alloying agents. This chapter addresses both roles, discussing the properties, processing characteristics, and applications of several categories of nonferrous metals, including light metals, corrosion-resistance alloys, superalloys, refractory metals, low-melting-point metals, reactive metals, precious metals, rare earth metals, and metalloids or semimetals. It also provides a brief summary on special-purpose materials, including uranium, vanadium, magnetic alloys, and thermocouple materials.

This chapter recounts some of the early efforts and milestones in the development of stainless steel powders and their use in powder metallurgy applications.

This article discusses the role of alloying in the production and use of low-expansion alloys such as iron-nickel (Invar), iron-nickel-chromium (Elinvar), and iron-nickel-cobalt (Super-Invar and Kovar). It explains how the coefficient of thermal expansion varies with nickel content and how it can be tailored, along with other properties, through appropriate alloying adjustments. The article also discusses the effect of alloying on Incoloy and Pyromet, which are classified as high-strength, controlled-expansion alloys.

Specific heat is a fundamental property that relates the total heat per unit mass added to a system to the resultant temperature change of the system. This chapter begins with the definition and historical development of specific heat. Thermodynamic and solid state relationships are presented which include discussions about lattice specific heat and the effects of magnetic and superconducting transitions. Data sources for practical applications and methods of estimating specific heat for materials are also included. The chapter concludes with a section concerning the measurement of specific heat at low temperatures.

This chapter provides a brief overview of nickel-iron-base, cobalt-base, and nickel-base superalloys, discussing their basic metallurgy and defining characteristics.