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.

Radioanalysis is an analytical technique that uses energy emitted by radioactive isotopes to measure the concentration of related elements in test samples. This article begins with a discussion on the principles of radioactive decay and various forms of emission, including alpha and beta-particle emission, positron emission, and gamma and x-ray emission. It compares and contrasts measurement techniques based on various detectors, namely, charged-particle detectors, photon detectors, counting and recording instruments, and radioactive decay spectrometers. It also addresses sample preparation, equipment and process safety, and the handling of radioactive gasses and materials. The article concludes with application examples involving the analysis of rare-earth elements and nuclear fuels.

This article describes the modification and inoculation of cast iron, and schematically illustrates the major effects of inoculation in gray cast irons. Inoculation could be considered as a common liquid-state treatment for all commercial cast irons (gray/compacted/ductile irons), while modification is essential to produce compacted graphite iron (intermediate level) and ductile iron. The article discusses the most important aspects of a gray cast iron inoculation treatment and the factors influencing its inoculation efficiency. It describes the modification and inoculation of ductile cast iron and compacted graphite cast iron.

Magnesium alloys are used predominantly for high-pressure die-cast applications in which the use of a deliberate heat treatment is uncommon. This article provides information on the heat treatment designations for magnesium alloys. It describes the effects of grain size on magnesium alloys and the relationship between hardness and mechanical properties of the alloys. The article discusses the effects of elements such as aluminum, zinc, manganese, rare earths, and yttrium, on precipitation hardening. It describes the types of heat treatment for magnesium alloys, including annealing, stress relieving, solution treating and aging, and reheat treating. The article also discusses the preventive measures for the common problems encountered in heat treating magnesium alloys; and the evaluation of the effectiveness of heat treating procedures. In addition, it presents the processing steps involved in the heat treatment of magnesium alloys and in the prevention and control of magnesium fires.

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.

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.

Magnesium and its alloys are among the most difficult metals to prepare for metallographic examination. This article describes specimen preparation processes, including sectioning, mounting, grinding, and polishing. It discusses macro and microexamination techniques as well as related etching processes, including macroetching and color etching based on polarized light enhancement. The article concludes with an overview of the effects of alloying elements, including aluminum, beryllium, calcium, copper, iron, lithium, manganese, rare earth metals, silicon, silver, strontium, thorium, tin, zinc, and zirconium.

Unlike gray iron, which contains graphite flakes, ductile iron has an as-cast structure containing graphite particles in the form of small, rounded, spheroidal nodules in a ductile metallic matrix. This article discusses the raw materials that are used for ductile iron production and outlines the most common and important requirements for controlling the composition of ductile iron. Treatment to produce ductile iron involves the addition of magnesium to change the form of the graphite, followed by or combined with inoculation of a silicon-containing material to ensure a graphitic structure with freedom from carbides. The article describes the methods of magnesium treatment, control of magnesium content, and inoculation. It concludes with a discussion on the metallurgical controls of ductile iron production.

Chemical elements are the basic chemical substances; that is, they cannot be decomposed by chemical change or made by chemical union. These elements follow a periodic pattern related to the atomic mass of each that allows them to be arranged into a convenient table. This article includes a series of tables: the first gives the names and symbols of the elements in alphabetical order and the second lists the elements in order by atomic number and give the atomic weight for each. The periodic table of the elements also is included in the article.

This article is a compilation of abbreviations and symbols related to metallography and microstructures.

Magnesium-matrix composites (MgMCs) are very promising as structural materials because of their low density, high specific strength, and excellent castability. This article provides information on the characteristics, mechanical properties, and applications of magnesium alloys and composites. It discusses the microstructures used for the most common magnesium alloys used in metal-matrix composites, namely, magnesium-aluminum, magnesium-rare earth and magnesium-lithium alloys. The article focuses on the most common methods of heat treatment, including solution heat treatment, precipitation strengthening or aging, and annealing, applied to these alloys. Finally, it describes the microstructural aspects and precipitate-matrix relationships of MgMCs as well as the heat treatment methods for MgMCs.

The morphology of the graphite particles in compacted graphite iron (CGI) is intermediate to the graphite particles found in gray iron or ductile iron. This article discusses the castability and product design of compacted graphite iron. The introduction of modern measurement and control technologies has made CGI a viable material for high-volume series production. The article describes the production of compacted graphite iron castings and the process control that depends on the production volume of components made from compacted graphite iron. It also discusses the process control for high-volume CGI commonly based on thermal analysis.

This article discusses the chief magnetic characteristics of permanent magnet materials. It provides a detailed description on nominal compositions; principal magnet designations; magnetic, physical, and mechanical properties; selection criteria; and applications of the permanent magnet materials, which include magnet steels, magnet alloys, alnico alloys, platinum-cobalt alloys, cobalt and rare-earth alloys, hard ferrites, iron-chromium-cobalt alloys, and neodymium-iron-boron alloys.

The International Committee of Foundry Technical Associations has identified seven basic categories of casting defects: metallic projections, cavities, discontinuities, defective surfaces, incomplete casting, incorrect dimension, and inclusions or structural anomalies. This article presents some of the common defects in each of the seven categories in a table. It discusses common defects determined during the examination of samples of ductile cast iron in Elkem's research facility in Norway. The article reviews common defects, such as shrinkage cavities, blowholes, hydrogen pinholes, nitrogen defects, and abnormal graphite morphology, found in gray iron. It concludes with a discussion on surface defects in compacted graphite iron.

Magnesium and magnesium alloys have been employed in a wide variety of structural applications because of their favorable combination of tensile strength, elastic modulus, and low density. Providing a brief section on occurrence, production, and uses of magnesium, this article describes alloy and temper designations of cast and wrought magnesium alloys. The role of mechanical properties and fabrication characteristics in selection of product forms for structural applications is covered. The article explores the use of magnesium alloys as a substitution for heavier metals such as steel and aluminum alloys to reduce weight in structural parts.