Engineers have many materials to choose from when dealing with weight-related design constraints. The list includes aluminum, beryllium, magnesium, and titanium alloys as well as engineering plastics, structural ceramics, and polymer-, metal-, and ceramic-matrix composites. This chapter provides a brief overview of these lightweight materials, discussing their primary advantages along with their properties, behaviors, and limitations.

This chapter provides basic engineering information on aluminum alloys with an emphasis on their use in applications where weight is a significant design factor. It discusses the advantages and limitations of various types of aluminum along with their compositions, designations, and achievable strengths. It explains how some alloys are hardened through solution strengthening and cold working, while others are strengthened by precipitation hardening. It also describes production and fabrication processes such as melting, casting, rolling, forging, forming, extruding, heat treating, and joining, and includes a section on the causes and effects of corrosion and how they are typically controlled.

Magnesium, by volume, is two-thirds the weight of aluminum and one-quarter the weight of steel. It also has good damping capacity, giving it an edge over other metals in high-vibration environments. This chapter discusses the basic metallurgy, alloy designations, compositions, and mechanical properties of cast and wrought magnesium alloys. It also describes the processes used to produce magnesium parts, the causes and effects of corrosion, and the use of protective coatings and treatments.

Beryllium is an extraordinary metal with an unusual combination of physical and mechanical properties. It has low density, high stiffness, and excellent dimensional stability. It is also transparent to x-rays and can be machined to extremely close tolerances. This chapter discusses the properties, compositions, and processing characteristics of beryllium and its alloys. It provides information on powder production and consolidation, commercial designations and grades, wrought products, and forming processes. It also discusses the issue of corrosion, the use of protective treatments and coatings, and health and safety concerns.

Titanium is a lightweight metal used in a growing number of applications for its strength, toughness, stiffness, corrosion resistance, biocompatibility, and high-temperature operating characteristics. This chapter discusses the applications, metallurgy, properties, compositions, and grades of commercially pure titanium and alpha and near-alpha, alpha-beta, and beta titanium alloys. It describes primary and secondary fabrication processes, including melting, forging, forming, heat treating, casting, machining, and joining as well as powder metallurgy and direct metal deposition. It also compares and contrasts the properties of wrought, cast, and powder metal titanium products and discusses corrosion behaviors.

Titanium aluminides are lightweight materials that have relatively high melting points and good high-temperature strength. They also tend to be stronger and lighter than conventional titanium alloys, but considerably less ductile. This chapter begins with a review of the titanium-aluminum phase diagram, focusing on the properties, compositions, and microstructures of alpha-2 Ti3Al alloys. It then describes the properties, microstructures, and compositions of orthorhombic, gamma, and near-gamma alloys as well as the processing methods and procedures normally used in their production.

This chapter describes the molecular structures and chemical reactions associated with the production of thermoset and thermoplastic components. It compares and contrasts the mechanical properties of engineering plastics with those of metals, and explains how fillers and reinforcements affect impact and tensile strength, shrinkage, thermal expansion, and thermal conductivity. It examines the relationship between tensile modulus and temperature, provides thermal property data for selected plastics, and discusses the effect of chemical exposure, operating temperature, and residual stress. The chapter also includes a section on the uses of thermoplastic and thermosetting resins and provides information on fabrication processes and fastening and joining methods.

Polymer-matrix composites are among the lightest structural materials in use today. They are also highly resistant to corrosion and fatigue and their load-carrying capabilities, such as strength and stiffness, can be tailored for specific applications. This chapter discusses the primary advantages and disadvantages of polymer-matrix composites, how they are produced, and how they perform in different applications. It describes the construction of laminates, the fibers and resins used, and the methods by which they are combined. It explains how strength, modulus, toughness, and high-temperature and corrosion behaviors are determined by the orientation, shape, and spacing of fibers, the number of plies, resin properties, and consolidation and forming methods. The chapter also covers secondary fabrication processes, such as thermoforming, machining, and joining, as well as production equipment and product forms, and include guidelines for optimizing tradeoffs when selecting fibers, resins, and production techniques.

Metal-matrix composites can operate at higher temperatures than their base metal counterparts and, unlike polymer-matrix composites, are nonflammable, do not outgas in a vacuum, and resist attack by solvents and fuels. They can also be tailored to provide greater strength and stiffness, among other properties, in preferred directions and locations. This chapter discusses the processes and procedures used in the production of fiber-reinforced aluminum and titanium metal-matrix composites. It explains how the length and orientation of reinforcing fibers affect the properties and processing characteristics of both aluminum and titanium composites. It also provides information on fiber-metal laminates and the use of different matrix metals and reinforcing materials.

Ceramics normally have high melting temperatures, excellent chemical stability and, due to the absence of conduction electrons, tend to be good electrical and thermal insulators. They are also inherently hard and brittle, and when loaded in tension, have almost no tolerance for flaws. This chapter describes the applications, properties, and behaviors of some of the more widely used structural ceramics, including alumina, aluminum titanate, silicon carbide, silicon nitride, zirconia, zirconia-toughened alumina (ZTA), magnesia-partially stabilized zirconia (Mg-PSZ), and yttria-tetragonal zirconia polycrystalline (Y-TZP). It also provides information on materials selection, design optimization, and joining methods, and covers every step of the ceramic production process.

Ceramic-matrix composites possess many of the desirable qualities of monolithic ceramics, but are much tougher because of the reinforcements. This chapter explains how reinforcements are used in ceramic-matrix composites and how they alter energy-dissipating mechanisms and load-carrying behaviors. It compares the stress-strain curves for monolithic ceramics and ceramic-matrix composites, noting improvements afforded by the addition of reinforcements. It then goes on to discuss the key attributes, properties, and applications of discontinuously reinforced ceramic composites, continuous fiber ceramic composites, and carbon-carbon composites. It also describes a number of ceramic-matrix composite processing methods, including cold pressing and sintering, hot pressing, reaction bonding, directed metal oxidation, and liquid, vapor, and polymer infiltration.

This chapter consists of three parts. The first part provides data and guidelines for selecting materials and processing routes. It compares the basic properties of metals, ceramics, and polymers, identifies important measures of performance, and discusses manufacturing processes and their compatibility with specific materials. The chapter then presents general guidelines for selecting lightweight materials, and concludes with a review of lightweight metals, plastics, and composites used in automotive applications.

Beryllium, despite its relatively simple atomic structure, possesses a wide range of useful engineering properties. It has the highest strength-to-weight ratio and modulus of elasticity among structural metals and is an important alloy addition in copper, nickel, and aluminum alloys. It also has excellent thermal properties, low atomic mass, a small x-ray absorption cross section, and a large neutron scattering cross section. This brief introductory chapter provides an overview of the unique qualities of beryllium along with typical applications and uses.

This chapter describes some of events and developments that helped drive the commercialization of beryllium and its acceptance as an engineering material. It traces the growth of the domestic beryllium industry from its origins in the 1920s to the present time, and provides a status update on the primary beryllium producers throughout the world.

Beryllium is the 44th most abundant element on Earth, with an estimated concentration of six parts per million in the Earth’s crust. It is found in various forms in more than 100 minerals, two of which, beryl and bertrandite, account for most of the beryllium produced throughout the world. This chapter describes where and how beryllium is obtained and provides facts, figures, and insights on global supply and demand.

This chapter provides a thorough review of the crystal structure of beryllium and its elastic, thermal, and nuclear properties. It also includes information on electrical and optical properties and an extensive amount of data in the form of tables and plots.

This chapter provides a fundamental understanding of beryllium reduction thermodynamics as a prerequisite for subsequent chapters on extraction, chemical processing, and corrosion. It examines a number of reduction methods along with a potential refining process, highlighting the challenges encountered with each.

This chapter describes some of the processes used to concentrate beryllium-rich minerals from ores. It discusses the flotation of bertrandite and phenacite from calcite, mica, fluorspar, and quartz-containing ores, the flotation of beryl from pegmatitic gangues and low-grade deposits, and the use of chemical activators and conditioning agents. It also explains that hand sorting is still very common because of processing challenges and inefficiencies.

This chapter describes some of the chemical processes that have been developed to extract beryllium from different types of ore. It covers the Kjellgren-Sawyer sulfate method, the Degussa method, Copaux-Kawecki fluoride extraction, solvent extraction, and leaching and settling. It also provides information on electrolytic extraction and the use of electrorefining.