In contrast to the situation with polymeric and ceramic materials, alpha-numeric designation systems are relatively well established and well known for metals and alloys. Unfortunately, since such designations are mostly based on composition alone and differ between alloy groups, major problems still occur in building computer files for an information system of broad scope in materials and properties. This paper reviews existing systems of designation for metals and alloys and outlines the approach taken for characterization of materials in the MIST demonstration program being built for the National Materials Property Data Network.
Designation systems for metallic materials have been formulated by the trade associations (for example, Aluminum Association [AA], Copper Development Association [CDA], and the American Iron and Steel Institute [AISI]), by professional societies (for example, ASTM), by user groups (for example, Military and Federal), and by private companies (both users and producers). Naturally this has led to a chaotic situation with many ambiguities and uncertainties. A big step forward was taken by ASTM-Society of Automotive Engineers (SAE) who established a Unified Numbering System (UNS), which provided a logical and unambiguous code for thousands of commercially important metallic materials. Unfortunately, not all significant alloys are included; the coding relates to composition alone; and the scheme has not been endorsed outside the United States by such bodies as the International Standards Organization (ISO), or the European Standards Association.
Since in general properties are not defined by composition alone further characterization must be provided. Among the features that must be noted are form, size, method of synthesis, post-processing treatments, applications, and so forth. Illustrations of the incorporation of all these descriptors are taken from the metadata structure built for the Materials Information for Science and Technology (MIST) system.