High-velocity gas motion occurs in and around the arc during welding. This article describes the phenomena of gas flow in gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW). The effect of trace element impurities on GTA weld penetration of selected alloys is presented in a table. The article concludes with a discussion on submerged arc welding (SAW).

The electronic microcircuit industry has placed severe demands on metal suppliers to provide metals of the highest reproducible purity attainable as a result of the constant quest for the true values of physical and chemical properties of metals. This article describes the commonly used methods for ultrapurification of metals produced by electrolytic processes, including fractional crystallization, zone refining, vacuum melting, distillation, chemical vapor deposition, and solid state refining techniques. In addition, it describes the trace element analysis and resistance-ratio test methods used to characterize purity. Tables list the values for resistance ratios of zone-refined metals and their corresponding chemical compositions, and provide an example of the detection of impurities to concentrations in the parts per billion range, utilizing a combination of the glow discharge mass spectroscopy method and Leco combustion methods.

This article provides an overview of the metallurgical effects on corrosion of different series of aluminum alloys (1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, and 7xxx) that are classified into two categories. The first category includes the effects from insoluble, intermetallic constituent particles generally formed from trace impurity elements that play a predominant role in pitting corrosion. The second category comprises the effects from precipitation of secondary phases and effects from solute remaining in solid solution on corrosion of aluminum.

Fluid flow is important because it affects weld shape and is related to the formation of a variety of weld defects in gas tungsten arc (GTA) welds. This article describes the surface-tension-driven fluid flow model and its experimental observations. The effects of mass transport on arc plasma and weld pool are discussed. The article reviews the strategies for controlling poor and variable penetration and describes the formation of keyhole and fluid flow in electron beam and laser welds. It also explains the fluid flow in gas metal arc welding and submerged arc welding, presenting its transport equations.

This article discusses the basic principles of inductively coupled plasma mass spectrometry (ICP-MS), covering different instruments used for performing ICP-MS analysis. The instruments covered include the sample-introduction system, ICP ion source, mass analyzer, and ion detector. Emphasis is placed on ICP-MS applications in the semiconductor, photovoltaic, materials science, and other electronics and high-technology areas.

Cast and wrought coppers can be strengthened by cold working. This article provides information on minor alloying elements, such as beryllium, silicon, nickel, tin, zinc, and chromium, used to strengthen copper. It details annealing and recrystallization and grain growth characteristics of copper. The article also discusses the tensile-stress-relaxation behavior of selected types of copper wires.

This article illustrates the equilibrium phase diagram for an aluminum-silicon system, showing the metastable extensions of liquidus and solidus lines. It describes the classification and microstructure of the aluminum-silicon eutectic. The article presents the theories of solidification and chemical modification of the aluminum-silicon eutectic.

This article provides a brief account of glow discharge mass spectrometry (GDMS) for direct determination of trace elements in solid samples and for fast depth profiling in a great variety of innovative materials. It begins by describing the general principles of GDMS. This is followed by a discussion on the various components of a GDMS system as well as commercial GDMS instruments. A description of processes involved in specimen preparation and cleaning in GDMS is then presented. Various problems pertinent to multielemental calibrations in GDMS are discussed along with measures to overcome them. The article further provides information on the processes involved in the analytical setup of parameters in GDMS, covering the steps involved in the analysis of GDMS data. It ends with a section on the application and interpretation of GDMS in the metals industry.

The characterization, testing, and nondestructive evaluation of ceramics and glasses are vital to manufacturing control, property improvement, failure prevention, and quality assurance. This article provides a broad overview of characterization methods and their relationship to property control, both in the production and use of ceramics and glasses. Important aspects covered include the means for characterizing ceramics and glasses, the corresponding rationale behind them, and relationship of chemistry, phases, and microconstituents to engineering properties. The article also describes the effects that the structure of raw ceramic materials and green products and processing parameters have on the ultimate structure and properties of the processed piece. The effects that trace chemistry and processing parameters have on glass properties are discussed. The article describes mechanical tests and failure analysis techniques used for ceramics.

This article briefly reviews the production methods and characteristics of plain carbon and low-alloy water-atomized iron and steel powders, high-porosity iron powder, carbonyl iron powder, and electrolytic iron powder. It emphasizes on atomized powders, because they are the most widely used materials for ferrous powder metallurgy. The article provides information on the properties and applications of these powders. It also includes an overview of diffusion alloying, basics of admixing, and bonded premixes.

The food-based approaches are considered important sustainable strategies for preventing iron deficiency. The success of a food fortification program depends on the choice of food vehicles and the choice of iron fortificants, that is, iron sources. This article discusses iron sources, namely, elemental irons and iron compounds, used as fortificants. Common elemental iron powders such as plain pure iron powders, and common iron compounds such as ferrous sulfate used in food fortifications, are reviewed. The article contains tables that list the food chemical codex requirements and the physical and chemical properties of commercial food-grade elemental irons.

The overall chemical composition of metals and alloys is most commonly determined by X-ray fluorescence (XRF) and optical emission spectroscopy (OES), and combustion and inert gas fusion analysis. This article provides information on the capabilities, uses, detection threshold and precision methods, and sample requirements. The amount of material that needs to be sampled, operating principles, and limitations of the stated methods are also discussed.

Neutron activation analysis (NAA) is a highly sensitive and accurate method of assaying bulk materials for trace levels of many elements. This article provides a detailed account on several types of NAA, namely, nondestructive and radiochemical thermal neutron activation, delayed neutron counting, epithermal and 14-MeV fast neutron activation, and prompt gamma activation analysis. It also includes application examples, explaining where and how each method is used and the types of elements on which they are effective.

In secondary ion mass spectroscopy (SIMS), an energetic beam of focused ions is directed at the sample surface in a high or ultrahigh vacuum (UHV) environment. The transfer of momentum from the impinging primary ions to the sample surface causes sputtering of surface atoms and molecules. This article focuses on the principles and applications of high sputter rate dynamic SIMS for depth profiling and bulk impurity analysis. It provides information on broad-beam instruments, ion microprobes, and ion microscopes, detailing their system components with illustrations. The article graphically illustrates the SIMS spectra and depth profiles of various materials. The quantitative analysis of ion-implantation profiles, instrumental features required for secondary ion imaging, the analysis of nonmetallic samples, detection sensitivity, and the applications of SIMS are also discussed.

This article provides a detailed account of the concepts and applications of neutron activation analysis (NAA), covering the basic principles and neutron reactions of NAA as well as calibration methods used for NAA. The discussion also covers the factors pertinent to analytical sensitivity achievable with NAA, common neutron sources, sample-handling technique, and automated systems of NAA. The categories of NAA covered are instrumental neutron activation analysis, epithermal neutron activation analysis, radiochemical neutron activation analysis, 14 MeV fast neutron activation analysis, delayed neutron activation analysis, and prompt gamma activation analysis.

This article briefly discusses popular techniques for metals characterization. It begins with a description of the most common techniques for determining chemical composition of metals, namely X-ray fluorescence, optical emission spectroscopy, inductively coupled plasma optical emission spectroscopy, high-temperature combustion, and inert gas fusion. This is followed by a section on techniques for determining the atomic structure of crystals, namely X-ray diffraction, neutron diffraction, and electron diffraction. Types of electron microscopies most commonly used for microstructural analysis of metals, such as scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy, are then reviewed. The article contains tables listing analytical methods used for characterization of metals and alloys and surface analysis techniques. It ends by discussing the objective of metallography.

Identification of alloys using quantitative chemical analysis is an essential step during a metallurgical failure analysis process. There are several methods available for quantitative analysis of metal alloys, and the analyst should carefully approach selection of the method used. The choice of appropriate analytical techniques is determined by the specific chemical information required, the condition of the sample, and any limitations imposed by interested parties. This article discusses some of the commonly used quantitative chemical analysis techniques for metals. The discussion covers the operating principles, applications, advantages, and disadvantages of optical emission spectroscopy (OES), inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray spectroscopy, and ion chromatography (IC). In addition, information on combustion analysis and inert gas fusion analysis is provided.

Vacuum induction melting (VIM) is often done as a primary melting operation followed by secondary melting (remelting) operations. This article presents the process description of VIM and illustrates potential processing routes for products, which are cast from VIM ingots or electrodes. It describes the VIM refinement process, which includes the removal of trace elements, nitrogen and hydrogen degassing, and deoxidation. The article concludes with information on the production of nonferrous materials by VIM.

This article focuses on the principles and applications of high-sputter-rate dynamic secondary ion mass spectroscopy (SIMS) for depth profiling and bulk impurity analysis. It begins with an overview of various factors pertinent to sputtering. This is followed by a discussion on the effects of ion implantation and electronic excitation on the charge of the sputtered species. The design and operation of the various instrumental components of SIMS is then reviewed. Details on a depth-profiling analysis of SIMS, the quantitative analysis of SIMS data, and the static mode of operation of time-of-flight SIMS are covered. Instrumental features required for secondary ion imaging are presented and the differences between quadrupole and high-resolution magnetic mass filters are described. The article also reviews the optimum method for analysis of nonmetallic samples and high detection sensitivity of SIMS. It ends with a discussion on a variety of examples of SIMS applications.

This article provides a thorough review of the physical metallurgy of aluminum alloys and its role in determining the properties and from a design and manufacturing perspective. And its role in include the effects of composition, mechanical working, and/or heat treatment on structure and properties. This article focuses on the effects of alloying and the metallurgical factors on phase constituents, structure, and properties of aluminum alloys. Effects from different combinations of alloying elements are described in terms of relevant alloy phase diagrams. The article addresses the underlying alloying and structural aspects that affect the properties and possible processing routes of aluminum alloys. It provides information on the heat treatment effects on the physical properties of aluminum alloys and the microstructural effects on the fatigue and fracture of aluminum alloys. The important alloying elements and impurities are listed alphabetically as a concise review of major effects.