This article discusses the general principles, optical systems, and emission sources of optical emission spectroscopy for elemental analysis. Changes in the energy of the valence or outer shell electrons result in the atomic lines used in emission spectroscopy. Each possible combination of electron configurations produces a spectroscopic term that describes the state of the atom. Atomic emission is analytically useful only to the extent that the emission from one atomic species can be measured and its intensity recorded independent of emission from other sources. Emission sources are often designed to minimize molecular emission. Each of the four types of emission sources; arcs, high-voltage sparks, glow discharges, and flames; has a set of physical characteristics with accompanying analytical assets and liabilities. The article also discusses the applications of each type of emission source.

Rare earth metals belong to Group IIIA of the periodic table that includes scandium, yttrium, and the lanthanide elements which are lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium. This article classifies the rare earth metals based on their purity level, which are designated as research grades (>99.8% pure) and commercial grades (95% - 98% pure), and describes the preparation and purification, including solid-state electrolysis. It further discusses physical, mechanical, and chemical properties; electronic configurations; crystal structures, and explains the alloy forming characteristics of rare earth elements. The article concludes by describing the various applications of commercial-grade rare earth elements and commercial alloys, which incorporates rare earth elements as additives.

This article provides basic information on the chemical elements and their arrangement into a periodic table based on recurring similarities in the fundamental nature of the elements. These elements follow a periodic pattern related to the electron configuration that allows them to be arranged into the convenient periodic table.

Electron beam welding (EBW) can produce deep, narrow, and almost parallel-sided welds with low total heat input and relatively narrow heat-affected zones in a wide variety of common and exotic metals. This article focuses on essential parameters of EBW, namely, weld and surface geometry, part configuration, melt-zone configuration, weld atmosphere (vacuum and nonvacuum), and joint design. It describes various aspects considered in EBW of thin and thick metal sections and poorly accessible joints. An overview of scanning and joint tracking techniques for inspection of electron beam-welded joints is also included. The article concludes with discussions on EBW defects, the use of filler metal for weld repair, and the control plans, codes, and specifications of the EBW process.

Electron-beam welding (EBW) can produce deep, narrow, and almost parallel-sided welds with low total heat input and relatively narrow heat-affected zones in a wide variety of common and exotic metals. This article discusses the joint configurations and shrinkage stresses encountered in various joint designs for electron-beam welding, as well as special joints and welds including multiple-pass welds, tangent-tube welds, three-piece welds, and multiple-tier welds. It provides a comparison of medium vacuum EBW with high-vacuum EBW. Scanning is a method of checking the run-out between the beam spot and the joint to be welded. The article describes various scanning techniques for welding dissimilar metals and provides information on the application of electron-beam wire-feed process for repairs. It concludes with a discussion on EBW of heat-resistant alloys, refractory metals, aluminum alloys, titanium alloys, copper and copper alloys, magnesium alloys, and beryllium.

This article provides basic information on chemical elements and their arrangement into a periodic table based on recurring similarities in the fundamental nature of the elements.

Explosion welding (EXW) is a solid-state metal-joining process that uses explosive force to create an electron-sharing metallurgical bond between two metal components. This article discusses the process attributes of EXW, including metallurgical attributes, metal combinations, size limitations, configuration limitations, and bond zone morphology. It provides an overview of the common industrial applications and shop welding applications of EXW products. The article reviews different safety standards and regulations, such as noise and vibration abatement and process geometry. It concludes with a section on the EXW process sequence for welding a two-component flat plate product.

Improvement in the corrosion performance of a component or structure can be achieved through proper design, surface protection, proper material selection, or combinations of all three parameters. This is an introductory article on the selection of nonferrous corrosion-resistant materials.