The application of two quantitative techniques to the measurement of gamma prime size, interparticle spacing, and volume fraction in two commercial heat resistant alloys is discussed. The two methods involve the use of structure and extraction replica electron microscopy and were evaluated for their ease of application and consistency of data using various measuring parameters.

The effects of structure control available from the precipitating phases in wrought superalloys were demonstrated in a recent review. It was shown that criteria for selection of superalloys should be reviewed periodically to establish that they reflect the state of the art. For example, expensive materials may have been specified where lower cost alloys could do a job equally well. This is especially true for superalloys in applications where properties up to about 1200°F are critical. This paper reviews some results of the continuing study by superalloy metallurgists to reveal means of “retrograding” elevated temperature requirements to lower cost compositions that, combined with proper processing, will meet property requirements. It is shown that microstructure studies, combined with knowledge of phase relationships, prove to be an invaluable tool. Recent examples of improved hot-work behavior, heat-treat response, and property development are reviewed. Effects of thermomechanical processing are also discussed.

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The desire and need to observe real structures and finer detail has resulted not only in higher performance electron microscopes but also resulted in a great deal of time and effort spent to design and develop better specimen preparation techniques. Since the first direct examination of thin metal foils in 1949 by Heindenreich[I], 2 many different methods of thin film preparation have evolved. This paper will not deal with transmission image interpretation but is intended as a review of procedures and basic techniques of thin foil preparation collected from literature and includes methods contributed by different laboratories represented on the American Society for Testing and Materials (ASTM) Subcommittee E04.11 on Electron Microscopy and Diffraction. Appendix 3.2 provides a complete bibliography of papers published in ASTM Special Technical Publications pertaining to thin foil preparation and applications of transmission electron microscopy of metals.

Description The symposium on MiCon 78: Optimization of Processing, Properties, and Service Performance Through Microstructural Control was held in Houston, Texas, 3-5 April 1978. Sponsored by Committee E-4 on Metallography of the American Society for Testing and Materials, the symposium was also cosponsored by The Metallurgical Society of the American Institute of Mining, Metallurgical, and Petroleum Engineers, the International Metallographic Society, and the Houston Chapter of the American Society for Metals. Dr. Halle Abrams, Bethlehem Steel Corporation, G. N. Maniar, Carpenter Technology Corporation, D. A. Nail, Cameron Iron Works, and Dr. H. D. Solomon, General Electric Company are editors of this publication.