Alloying, heat treating, and work hardening are widely used to control material properties, and though they take different approaches, they all focus on imperfections of one type or other. This chapter provides readers with essential background on these material imperfections and their relevance in design and manufacturing. It begins with a review of compositional impurities, the physical arrangement of atoms in solid solution, and the factors that determine maximum solubility. It then describes different types of structural imperfections, including point, line, and planar defects, and how they respond to applied stresses and strains. The chapter makes extensive use of graphics to illustrate crystal lattice structures and related concepts such as vacancies and interstitial sites, ion migration, volume expansion, antisite defects, edge and screw dislocations, slip planes, twinning planes, and dislocation passage through precipitates. It also points out important structure-property correlations.

This appendix provides a detailed overview of the crystal structure of metals. It describes primary bonding mechanisms, space lattices and crystal systems, unit cell parameters, slip systems, and crystallographic planes and directions as well as plastic deformation mechanisms, crystalline imperfections, and the formation of surface or planar defects. It also discusses the use of X-ray diffraction for determining crystal structure.

The building block of all matter, including metals, is the atom. This chapter initially provides information on atomic bonding and the crystal structure of metals and alloys, followed by a description of three crystal lattice structures of metals: face-centered cubic, hexagonal close-packed, and body-centered cubic. It then describes the four main divisions of crystal defects, namely point defects, line defects, planar defects, and volume defects. The chapter provides information on grain boundaries of metals, processes involved in atomic diffusion, and key properties of a solid solution. It also explains the aspects of a phase diagram that shows what phase or phases are present in the alloy under conditions of thermal equilibrium. Finally, a discussion on the applications of equilibrium phase diagrams is presented.

Deformation within a crystal lattice is governed principally by the presence of dislocations, which are two-dimensional defects in the lattice structure. Slip from shear stress is the most common deformation mechanism within crystalline lattices of metallic materials, although deformation of crystal lattices can also occur by other processes such as twinning and, in special circumstances, by the migration of vacant lattice sites. This appendix describes the notation used to specify lattice planes and directions and discusses the mechanisms of slip and twinning as well as the effect of stacking faults.

This chapter discusses the basic principles of alloying and their practical application in the production of titanium mill products and engineered parts. It begins with a review of the atomic and crystal structure of titanium and the conditions for interstitial and substitutional alloying. It then describes the different classes of alloying elements, their effect on mechanical properties and behaviors, and their influence on phase transitions and transformations. The chapter also discusses the role of intermetallic compounds and their effect on crystal structure and creep behavior.

This chapter introduces many of the key concepts on which metallurgy is based. It begins with an overview of the atomic nature of matter and the forces that link atoms together in crystal lattice structures. It discusses the types of imperfections (or defects) that occur in the crystal structure of metals and their role in mechanical deformation, annealing, precipitation, and diffusion. It describes the concept of solid solutions and the effect of temperature on solubility and phase transformations. The chapter also discusses the formation of solidification structures, the use of equilibrium phase diagrams, the role of enthalpy and Gibb’s free energy in chemical reactions, and a method for determining phase compositions along the solidus and liquidus lines.

This chapter provides readers with worked solutions to more than 25 problems related to compositional impurities and structural defects. The problems deal with important issues and challenges such as the design of low-density steels, the causes and effects of distortion in different crystal structures, the ability to predict the movement of dislocations, the influence of impurities on defects, the relationship between gain size and material properties, the identification of specific types of defects, the selection of compatible metals for vacuum environments, and the effect of twinning planes on stacking sequences. The chapter also includes problems on how the formation of precipitates can produce slip planes and how grain boundaries can act as obstacles to dislocation motion.

This chapter discusses the foundational principles of materials science. It begins with a review of the periodic table and the fundamental particles, including atoms, ions, and molecules, that constitute matter. It also reviews the types of bonds that form between atoms and the relative levels of force they produce. It describes the difference between crystalline and noncrystalline or amorphous materials and discusses common crystal structures, including face-centered cubic, body-centered cubic, hexagonal close packed, and diamond cubic. It also describes the structure of sodium chloride and includes a list of structurally similar compounds.

This chapter explains the basic terminology and principles of metallurgy as they apply to extrusion. It begins with an overview of crystal structure in metals and alloys, including crystal defects and orientation. This is followed by sections discussing the development of the continuous cast microstructure of aluminum and copper alloys. The discussion provides information on billet and grain segregation and defects in continuous casting. The chapter then discusses the processes involved in the deformation of pure metals and alloys at room temperature. Next, it describes the characteristics of pure metals and alloys at higher temperatures. The processes involved in extrusion are then covered. The chapter provides details on how the toughness and fracture characteristics of metals and alloys affect the extrusion process. The weld seams in hollow profiles, the production of composite profiles, and the processing of composite materials, as well as the extrusion of metal powders, are discussed. The chapter ends with a discussion on the factors that define the extrudability of metallic materials and how these attributes are characterized.

This appendix provides crystal structure and property data for alloying elements used in superalloys.

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 appendix explains how to calculate atomic packing factors, lattice parameters, and coordination numbers for cubic crystal structures, including simple, body-centered, and face-centered cubic systems. It also addresses hexagonal close-packed systems.

Steels are over 95% Fe, so a good starting point for understanding steel is to study the nature of solid iron. This chapter provides information on the composition, phase transformation, and associated changes in the crystal structure of pure iron at varying temperatures.

This chapter describes the metallurgy of superalloys and the extent to which it can be controlled. It discusses the alloying elements, crystal structures, and processing sequences associated with more than a dozen phases that largely determine the characteristics of superalloys, including their properties, behaviors, and microstructure. It examines the role of more than 20 alloying elements, including phosphorus (promotes carbide precipitation), boron (improves creep properties), lanthanum (increases hot corrosion resistance), and carbon and tungsten which serve as matrix stabilizers. It explains how precipitates provide strength by impeding deformation under load. It also discusses the factors that influence grain size, shape, and orientation and how they can be controlled to optimize mechanical and physical properties.

The existence of austenite and ferrite, along with carbon alloying, is fundamental in the heat treatment of steel. In view of the importance of structure and its formation to heat treatment, this chapter describes the various microstructures that form in steels, the various factors that determine the formation of microstructures during heat treatment processing of steel, and some of the characteristic properties of each of the microstructures. The discussion also covers the constitution of iron during heat treatment and the phases of heat-treated steel with elaborated information on iron phase transformation, hysteresis in heating and cooling, ferrite and austenite as two crystal structures of solid iron, and the diffusion coefficient of carbon.

This chapter discusses the properties and applications of beryllium intermetallic compounds. It describes the crystal structure of key beryllides, the metals they contain, and important properties such as high-temperature strength, thermal conductivity and expansion, oxidation resistance, and density. It explains how beryllide intermetallics are formed using sputter deposition, diffusion, and powder metal methods.

This appendix contains a table listing the symbol, atomic number, atomic weight, melting temperature, density, atomic radius, and crystal structure of various elements.

Ferritic stainless steels are essentially iron-chromium alloys with body-centered cubic crystal structures. Chromium content is usually in the range of 11 to 30%. The primary advantage of the ferritic stainless steels, and in particular the high-chromium, high-molybdenum grades, is their excellent stress-corrosion cracking resistance and good resistance to pitting and crevice corrosion in chloride environments. This chapter provides information on the classifications, properties, and general welding considerations of ferritic stainless steels. The emphasis is placed on intergranular corrosion, which is the most common cause of failure in ferritic stainless steel weldments. Two case histories involving intergranular corrosion failures of ferritic stainless steel weldments are included. A brief discussion on hydrogen embrittlement is also provided.

Martensitic stainless steels are essentially iron-chromium-carbon alloys that possess a body-centered tetragonal crystal structure (martensitic) in the hardened condition. Martensitic stainless steels are similar to plain carbon or low-alloy steels that are austenitized, hardened by quenching, and then tempered for increased ductility and toughness. This chapter provides a basic understanding of grade designations, properties, corrosion resistance, and general welding considerations of martensitic stainless steels. It also discusses the causes for hydrogen-induced cracking in martensitic stainless steels and describes sulfide stress corrosion resistance of type 410 weldments.

This chapter discusses the engineering significance of steel and briefly describes its chemical composition, crystal structure, Fe-C phases, and associated characterization techniques.