Ultraviolet/visible (UV/VIS) absorption spectroscopy is a powerful yet cost-effective tool that is widely used to identify organic compounds and to measure the concentration of principal and trace constituents in liquid, gas, and solid test samples. This article emphasizes the quantitative analysis of elements in metals and metal-bearing ores. The instrumentation required for such applications consists of a light source, a filter or wavelength selector, and some type of visual or automated sensing mechanism. The article examines common sensing options and provides helpful information on how to set up and run a variety of UV/VIS absorption tests.

Inductively coupled plasma atomic emission spectroscopy (ICP-AES) is an analytical technique for elemental determinations in the concentration range of major to trace based on the principles of atomic spectroscopy. This article provides a description of the basic atomic theory, and explains the analytical procedures and various interference effects of ICP, namely, spectral, vaporization-atomization, and ionization. It provides a detailed discussion on the principal components of an analytical ICP system, namely, the sample introduction system; ICP torch and argon gas supplies; radio-frequency generator and associated electronics; spectrometers, such as polychromators and monochromators; detection electronics and interface; and the system computer with appropriate hardware and software. The article also describes the uses of direct-current plasma, and provides examples of the applications of ICP-AES.

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.

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.

This article is a detailed account of the principles of electron-excited X-ray microanalysis. It begins by discussing the physical basis of electron-excited X-ray microanalysis and the advantages and limitations of energy dispersive spectrometry (EDS) and wavelength dispersive spectrometry for electron probe microanalysis. Key concepts for performing qualitative analysis and quantitative analysis by electron-excited X-ray spectrometry are then presented. Several sources that lead to measurement uncertainties in the k-ratio/matrix corrections protocol are provided, along with the significance of the raw analytical total. Sections on accuracy of the standards-based k-ratio/matrix corrections protocol with EDS and processes of analysis when severe peak overlap occurs are also included. The article provides information on low-atomic-number elements, iterative qualitative-quantitative analysis for complex compositions, and significance of standardless analysis in the EDS software. It ends with a section on the processes involved in elemental mapping for major and minor constituents.

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.

Atomic absorption spectrometry (AAS) is generally used for measuring relatively low concentrations of approximately 70 metallic or semimetallic elements in solution samples. This article describes several features that are common to three techniques, namely, AAS, atomic emission spectrometry (AES), and atomic fluorescence spectrometry (AFS). It discusses the reasons for the extreme differences in AAS sensitivities that affect AFS and AES. The article provides information on the advantages and disadvantages of the Smith/Hieftje system and two types of background correction systems, namely, the continuum-source background correction and Zeeman background correction. It also provides a list of applications of conventional AAS equipment, which includes most of the types of samples brought to laboratories for elemental analyses.

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.

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.

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.

This article introduces various analytical techniques commonly used in the characterization of organic solids and liquids and discusses the challenges in performing the analysis, with examples. Some general advice in approaching a material analysis is also provided.

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).

During the melting and solidification of cast irons, certain trace (minor) elements may unintentionally accumulate to an extent that they have a detrimental effect on the microstructure of castings. This article discusses the residual elements, trace elements, and tramp elements in cast irons. Elements that influence the matrix structure of cast irons are commonly classified as ferrite-promoting elements or pearlite-promoting elements. The article describes the effects of minor elements on microstructure and properties of cast irons. It discusses the use of a combination of tools to control the effects of minor elements on the structure and properties of cast irons. The article concludes with information on allowable levels of trace and tramp elements in cast irons.

Spark source mass spectrometry (SSMS) is an analytical technique used for determining the concentration of elements in a wide range of solid samples, including metals, semiconductors, ceramics, geological and biological materials, and air and water pollution samples. This article discusses the basic principles of spark source technique; SSMS instrumentation such as ion source, electric sector, and magnetic sector; sample preparation; and test procedures of SSMS. Some of the related techniques to SSMS are laser ionization mass spectrometry and laser-induced resonance ionization mass spectrometry. The ions produced in SSMS are detected by either the photometric method or electrical detection method and quantitatively measured by techniques such as internal standardization techniques, isotope dilution, multi element isotope dilution, and dry spike isotope dilution. The detected spark source spectrum contains all the elemental data of the tested sample. Finally, the article exemplifies the applications of SSMS.

This article describes some of the common elemental composition analysis methods and explains the concept of referee and economy test methods in failure analysis. It discusses different types of microchemical analyses, including backscattered electron imaging, energy-dispersive spectrometry, and wavelength-dispersive spectrometry. The article concludes with information on specimen handling.

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.

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 provides a clear but nonexhaustive description of the general principle of atomic emission, with a particular focus on instrumentation, and summarizes the main characteristics of the inductively coupled plasma optical emission spectrometer technique. Basic atomic theory as well as the instrument characteristics and their influence on the instrument performances are presented. The advantages, drawbacks, and developments of this technique are discussed, and, finally, alternative techniques and examples of applications are provided.

Electron probe microanalysis (EPMA) makes it possible to combine structural and compositional analysis in one operation. This article describes the basic concepts of microanalysis and the processing of EPMA that involves the measurement of the characteristic X-rays emitted from a microscopic part of a solid specimen bombarded by a beam of accelerated electrons. It provides information on the various aspects of energy-dispersive spectrometry (EDS) and wavelength-dispersive spectrometry (WDS), and elucidates the qualitative analysis of the major constituents of EDS and WDS. The article includes information on the analog and digital compositional mapping of elemental distribution, and describes the strengths and weaknesses of WDS and EDS spectrometers in X-ray mapping. It also outlines the application of EPMA for solving various problems in materials science.

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.