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 examines the effect of heat treating and other processes on the microstructure-property relationships that occur in superalloys. It discusses precipitation and grain-boundary hardening and how they influence the phases, structures, and properties of various alloys. It explains how the delta phase, which is used to control grain size in IN-718, improves strength and prevents stress-rupture embrittlement. It describes heat treatments for different product forms, discusses the effect of tramp elements on grain-boundary ductility, and explains how section size and test location influence measured properties. It also provides information and data on the physical and mechanical properties of superalloys, particularly tensile strength, creep-rupture, fatigue, and fracture, and discusses related factors such as directionality, porosity, orientation, elongation, and the effect of coating and welding processes.

This chapter describes how the phases are arranged into desired microstructures during the heat treatment of tool steels. It describes the microstructural changes that are the objectives of the austenitizing, quenching, and tempering steps of tool steel hardening. The chapter covers austenite composition, retained austenite, and austenite grain size and grain growth. It provides information on the hardness and hardenability of tool steel. The chapter reviews some of these concepts and describes the microstructural appearance of the products of diffusion-controlled transformation of austenite. The role that diffusion-controlled phase transformations play relative to the hardenability of high-carbon and alloy tool steels is then emphasized. It presents general considerations of transformation diagrams, Jominy curves, and the hardenability of tool steels. The factors related to the kinetics and stabilization of martensite transformation are also covered. It briefly reviews selected aspects of the changes that evolve during tempering.

Superalloys, except those with high aluminum and titanium contents, are welded with little difficulty. They can also be successfully brazed. This chapter describes the welding and brazing processes most often used and the factors that must be considered when making application decisions. It discusses the basic concepts of fusion welding and the differences between solid-solution-hardened and precipitation-hardened wrought superalloys. It addresses joint integrity, design, weld-related cracking, and the effect of grain size, precipitates, and contaminants. It covers common fusion welding techniques, defect prevention, fixturing, heat treatments, and general practices, including the use of filler metals. It also discusses several solid-state welding methods, superplastic forming, and transient liquid phase bonding, a type of diffusion welding process. The chapter includes extensive information on brazing processes, atmospheres, filler metals, and surface preparation procedures. It also includes examples of nickel-base welded components for aerospace use.

This chapter discusses the failure of superalloy components in high-temperature applications where they are subject to the effects of microstructural changes, melting, and corrosion. It explains how overheating can deplete alloying elements and alter the composition and distribution of phases, and how these processes contribute to microstructural changes as a function of time, temperature, and applied stress. It also describes several failure examples and discusses related issues, including damage recovery, refurbishment, and repair.

Carbon and low-alloy steels are the most frequently welded metallic materials, and much of the welding metallurgy research has focused on this class of materials. Key metallurgical factors of interest include an understanding of the solidification of welds, microstructure of the weld and heat-affected zone (HAZ), solid-state phase transformations during welding, control of toughness in the HAZ, the effects of preheating and postweld heat treatment, and weld discontinuities. This chapter provides information on the classification of steels and the welding characteristics of each class. It describes the issues related to corrosion of carbon steel weldments and remedial measures that have proven successful in specific cases. The major forms of environmentally assisted cracking affecting weldment corrosion are covered. The chapter concludes with a discussion of the effects of welding practice on weldment corrosion.

This chapter provides an overview of the fundamental material- and process-related parameters of quenching on residual stress, distortion control, and cracking. It begins with a description of phase transformations during heating and quenching of steel. This is followed by a section on the effects of materials and quench process design on distortion of steel during heat treating. Details on stress raisers and their role in quench cracking are then presented. The chapter ends with various selected case histories of failures attributed to the quenching process.

This chapter provides a practical understanding of heat treatments and how to employ them to optimize the properties and structures of cast irons and steels. It discusses annealing, normalizing, quenching, tempering, patenting, carburizing, nitriding, carbonitriding, and nitrocarburizing. It describes the primary objectives of each treatment along with processing sequences, process parameters, and related phase transformations. The chapter contains more than 100 images, including time-temperature diagrams, transformation curves, data plots, and detailed micro- and macrographs. It also discusses the concepts of hardenability, critical diameter, quench severity, and Jominy testing.

This chapter is a detailed account of various factors pertinent to the development and launch of a product. It begins by describing the five phases in the product launch process, namely product design and development, process design and development, product and process validation, product launch, and continuous improvement. This is followed by sections covering product-process flow diagrams and also the process elements considered for process failure mode and effects analysis. Some of the aspects covered by the engineering specifications to meet the product performance requirements are then reviewed. Details on product validation requirements and definitions of parameters related to the launch process are also provided. The chapter discusses the purpose of manufacturing control plan, along with an illustration of a manufacturing control plan outlined for a safety-critical suspension casting. It ends with an overview of the contents of a program launch manual.

This chapter is a compilation of beryllium phase diagrams, representing more than 25 binary alloy systems from beryllium-aluminum to beryllium-zirconium. Each diagram is presented along with a summary and source reference.

This chapter describes three approaches for 3D hot-spot localization of thermally active defects by lock-in thermography (LIT). In the first section, phase-shift analysis for analyzing stacked die packages is performed. The second example employs defocusing sequences for the localization of resistive electrical shorts in 3D architectures, and the third operates in cross sectional LIT mode to investigate defects in the insulation liner of Through Silicon Vias. All three approaches allow for a precise localization of thermally active defects in all three spatial dimensions to guide subsequent high-resolution physical analyses.

This chapter presents a discussion on the grain sizes and boundaries in nanocrystals. It discusses the third-generation nanotechnology in advanced high-strength steels.

This chapter provides a classification of the types of microstructural changes and transformations and then reviews each type. It presents the Johnson-Mehl-Avrami-Kolmogorov (JMAK) equation and explains the thermodynamics of eutectic solidification and eutectoid transformation. An appendix covers growth of eutectoid structure in carburized pearlite.