This chapter discusses the construction, interpretation, and use of ternary phase diagrams. It begins by examining a hypothetical phase space diagram and several corresponding two-dimensional plots. It then describes one of the most basic tools of metallurgy, the Gibbs triangle, and explains how to construct tie lines to analyze intermediate compositions and phases. It also discusses the use of three-dimensional temperature-composition diagrams, three- and four-phase equilibrium phase diagrams, and binary and ternary phase diagrams associated with the iron-chromium-nickel alloy system.

Phases are distinct states of aggregation of matter and one of the primary leverage points for understanding and applying materials. This chapter discusses the phase nature of metals and alloys, the concept of solid solutions, and the use of phase diagrams. It also describes some of the metallurgical effects of freezing or solidification, including the segregation of solutes and the formation of metal glasses.

This chapter discusses some of the methods and measurements used to construct phase diagrams. It explains how cooling curves were widely used to determine phase boundaries, and how equilibrated alloys examined under controlled heating and cooling provide information for constructing isothermal and vertical sections as well as liquid projections. It also explains how diffusion couples provide a window into local equilibria and identifies typical phase diagram construction errors along with problems stemming from phase-boundary curvatures and congruent transformations.

This chapter discusses the unique characteristics of isomorphous alloy systems. It begins with a review of the naming conventions for multi-component systems and the construction of a three-dimensional phase diagram for a two-component alloy system. It explains how phase diagrams can be constructed from time-temperature cooling curves and how they can be used to predict the phases present, their chemical compositions, and relative amounts. It also shows how phase diagrams can be modified to account for nonequilibrium cooling conditions.

Phase diagrams are graphical representations that show the phases present in the material at various compositions, temperatures, and pressures. This chapter begins with a section describing the construction of phase diagrams for the simple binary isomorphous system. A binary phase diagram can be used to determine three important types of information: the phases that are present, the composition of the phases, and the percentages or fractions of the phases. The chapter then describes the construction of one common type of binary phase diagram i.e., the eutectic alloy system. The major eutectic systems include the aluminum-silicon eutectic system and the lead-tin eutectic system. The chapter discusses the construction of eutectic phase diagrams from free energy curves. It also provides information on peritectic, monotectic, and solid-state reactions in alloy systems. The presence of intermediate phases is also described. Finally, a brief section provides some information on ternary phase diagrams.

This appendix provides a brief introduction to Thermo-Calc, explains what it is, and lists its uses. Instructions for accessing a demonstration version of the software are also provided.

This chapter describes the structures, phases, and phase transformations observed in metals and alloys as they solidify and cool to lower temperatures. It begins with a review of the solidification process, covering nucleation, grain growth, and the factors that influence grain morphology. It then discusses the concept of solid solutions, the difference between substitutional and interstitial solid solubility, the effect of alloying elements, and the development of intermetallic phases. The chapter also covers the construction and use of binary and ternary phase diagrams and describes the helpful information they contain.

The die casting process is a widely applied technique used by a variety of industries. This chapter reviews the casting design and engineering requirements for optimizing the characteristics of die castings.

This chapter provides an overview of a computational method, called CALPHAD, used for the study of phase equilibria in multicomponent systems. It describes the thermodynamic models and calculation techniques employed in the software and explains how it applies to complex alloys used in industry. It also provides examples showing how CALPHAD has been used to determine the formability of metallic glass, calculate the dilation of stainless steel during phase transformation, and predict the beta transus and approach curves of commercial titanium alloys.

This chapter provides an overview of key elements in controlling the casting process, systems to confirm the quality of outgoing components, and the steps needed to launch a novel product. The discussion also provides information on process control tools and techniques; incoming material control; process control of sand preparation and system maintenance; metallic charge materials; product quality control; and melting, metallurgical, and mechanical testing.

This chapter presents an overview of families of brazing alloys that one is likely to encounter in a manufacturing environment. It discusses the metallurgical aspects of brazing and includes a survey of brazing alloy systems. A discussion of deleterious and beneficial impurities is provided with examples. The chapter also describes the application of phase diagrams to brazing.

Brazing and soldering processes use a molten filler metal to wet the mating surfaces of a joint, with or without the aid of a fluxing agent, leading to the formation of a metallurgical bond between the filler and the respective components. This chapter discusses the characteristics, advantages, and disadvantages of brazing and soldering. The first part focuses on the fundamentals of the brazing process and provides information on filler metals and specific brazing methods. The soldering portion of the chapters provides information on solder alloys used, selection criteria for base metal, the processes involved in precleaning and surface preparation, types of fluxes used, solder joint design, and solder heating methods.

This chapter describes the various phases that form in tool steels, starting from the base of the Fe-C system to the effects of the major alloying elements. The emphasis is on the phases themselves: their chemical compositions, crystal structures, and properties. The chapter also provides general considerations of phases and phase diagrams and the determination of equilibrium phase diagrams. It describes the formation of martensite, characteristics of alloy carbides, and the design of tool steels.

This chapter provides a brief overview of phase diagrams, explaining what they represent and how and why they are used. It identifies key points, lines, and features on a binary nickel-copper phase diagram and explains what they mean from a practical perspective. It also discusses the concept of equilibrium, the significance of Gibb’s phase rule, the theorem of Le Chatelier, and the use of the lever rule.

This chapter explains how the principles of chemical thermodynamics are used in the construction and interpretation of phase diagrams. After a brief review of the laws of thermodynamics, it describes the concept of Gibbs free energy and its application to transformations that occur in single-component and binary solid solutions. It then examines the relationship between the free energy of a solution and the chemical potentials of the individual components. It also explains how to account for the heat of mixing using quasi-chemical models, discusses the effect of interatomic bond energies and chemical potentials, and shows how the equilibrium state of an alloy can be obtained from free-energy curves.

This chapter discusses the processes involved in the wetting, spreading, and chemical interaction of a braze on a nonmetal. The chapter reviews the key materials and process issues relating to the joining of nonmetals using active brazing. Emphasis is placed on the differences in brazing to metals by established methods. The chapter also describes the designing process and properties of metal/nonmetal joints.

This chapter introduces the concepts of mechanical properties and the various underlying metallurgical mechanisms that can be used to alter the strength of materials. The mechanical properties discussed include elasticity, plasticity, creep deformation, fatigue, toughness, and hardness. The strengthening mechanisms covered are solid-solution strengthening, cold working, and dispersion strengthening. The effect of grain size on the yield strength of a material is also discussed.

Failure analysis of steel welds may be divided into three categories. They include failures due to design deficiencies, weld-related defects usually found during inspection, and failures in field service. This chapter emphasizes the failures due to various discontinuities in the steel weldment. These include poor workmanship, a variety of hydrogen-assisted cracking failures, stress-corrosion cracking, fatigue, and solidification cracking in steel welds. Hydrogen-assisted cracking can appear in four common forms, namely underbead or delayed cracking, weld metal fisheyes, ferrite vein cracking, and hydrogen-assisted reduced ductility.