ALUMINUM PROCESSING

preparation of the ore for use in various products. Aluminum, or aluminium (Al), is a silvery white metal with a melting point of 660 C (1,220 F) and a density of 2.7 grams per cubic centimetre. The most abundant metallic element, it constitutes 8.1 percent of the Earth's crust. In nature it occurs chemically combined with oxygen and other elements. In the pure state it is soft and ductile, but it can be alloyed with many other elements to increase strength and provide a number of useful properties. Alloys of aluminum are light, strong, and formable by almost all known metalworking processes. They can be cast, joined by many techniques, and machined easily, and they accept a wide variety of finishes. In addition to its low density, many of the applications of aluminum and its alloys are based on its high electrical and thermal conductivity, high reflectivity, and resistance to corrosion. It owes its corrosion resistance to a continuous film of aluminum oxide that grows rapidly on a nascent aluminum surface exposed to air. Additional reading Comprehensive and up-to-date information on many aspects of metallurgy, individual metals, and alloys can be found in convenient reference-form arrangement in the following works: Metals Handbook, 9th ed., 17 vol. (197889), a massive and detailed source prepared under the direction of the American Society for Metals, with a 10th edition that began publication in 1990; Herman F. Mark et al. (eds.), Encyclopedia of Chemical Technology, 3rd ed., 31 vol. (197884), formerly known as Kirk-Othmer Encyclopedia of Chemical Technology, with a 4th edition begun in 1991; and its European counterpart, the first English-language edition of a monumental German work, Ullmann's Encyclopedia of Industrial Chemistry, 5th, completely rev. ed., edited by Wolfgang Gerhartz et al. (1985 ). The Editors of the Encyclopdia Britannica John E. Hatch (ed.), Aluminum: Properties and Physical Metallurgy (1984), is a reference work that treats aluminum and its alloys in their many product forms, covering properties of pure aluminum, physical metallurgy, metallography and characteristics of aluminum alloys, and nominal properties of many commercial alloys. A.K. Vasudevan and R.D. Doherty (eds.), Aluminum AlloysContemporary Research and Applications (1989), contains articles ranging from the history of wrought aluminum alloy development to the physical metallurgy of highly sophisticated aluminum alloy products using rapid solidification processing. Aluminum Standards and Data (biennial) is a publication of the Aluminum Association that includes ranges as well as nominal chemical compositions of all aluminum alloys, along with physical and mechanical properties and definitions of tempers. The development of aluminum alloys for the aerospace industry, including alloys for use at elevated temperatures, is discussed in Edgar A. Starke, Jr., Alloying of Aluminum: Development of New Aluminum Alloys, in John L. Walter, Melvin R. Jackson, and Chester T. Sims (eds.), Alloying (1988), pp. 165197. Rhea Berk et al., Aluminum, Profile of the Industry, 1982 (1982), examines the world aluminum industry broadly, in nontechnical language, at the same time providing worthwhile information for professionals. Peter R. Bridenbaugh James T. Staley